51工具盒子1、拉取镜像 {#1拉取镜像}
执行下面的命令拉取redis的docker镜像
docker pull redis
2、编写docker-compose.yml文件 {#2编写docker-composeyml文件}
内容如下：
version: '3'
services:
redis:
restart: always
image: redis
container_name: redis
ports:
- 50020:6379
environment:
TZ: Asia/Shanghai
volumes:
- ./data:/data
- ./conf/redis.conf:/etc/redis.conf
privileged: true
3、创建目录文件 {#3创建目录文件}
根据docker-compose.yml文件创建对应目录文件
pwd
mkdir data
mkdir conf
ll
4、编写Redis的配置文件 {#4编写redis的配置文件}
在conf目录下创建redis.conf文件，文件内容如下：
# Redis configuration file example.
#
# Note that in order to read the configuration file, Redis must be
# started with the file path as first argument:
#
# ./redis-server /path/to/redis.conf
Note on units: when memory size is needed, it is possible to specify
====================================================================
it in the usual form of 1k 5GB 4M and so forth:
===============================================
1k =\> 1000 bytes
=================
1kb =\> 1024 bytes
==================
1m =\> 1000000 bytes
====================
1mb =\> 1024\*1024 bytes
========================
1g =\> 1000000000 bytes
=======================
1gb =\> 1024*1024*1024 bytes
============================
units are case insensitive so 1GB 1Gb 1gB are all the same.
===========================================================
################################## INCLUDES ###################################
Include one or more other config files here. This is useful if you
==================================================================
have a standard template that goes to all Redis servers but also need
=====================================================================
to customize a few per-server settings. Include files can include
=================================================================
other files, so use this wisely.
================================
Note that option "include" won't be rewritten by command "CONFIG REWRITE"
=========================================================================
from admin or Redis Sentinel. Since Redis always uses the last processed
========================================================================
line as value of a configuration directive, you'd better put includes
=====================================================================
at the beginning of this file to avoid overwriting config change at runtime.
============================================================================
If instead you are interested in using includes to override configuration
=========================================================================
options, it is better to use include as the last line.
======================================================
include /path/to/local.conf
===========================
include /path/to/other.conf
===========================
################################## MODULES #####################################
Load modules at startup. If the server is not able to load modules
==================================================================
it will abort. It is possible to use multiple loadmodule directives.
====================================================================
loadmodule /path/to/my_module.so
================================
loadmodule /path/to/other_module.so
===================================
################################## NETWORK #####################################
By default, if no "bind" configuration directive is specified, Redis listens
============================================================================
for connections from all available network interfaces on the host machine.
==========================================================================
It is possible to listen to just one or multiple selected interfaces using
==========================================================================
the "bind" configuration directive, followed by one or more IP addresses.
=========================================================================
Each address can be prefixed by "-", which means that redis will not fail to
============================================================================
start if the address is not available. Being not available only refers to
=========================================================================
addresses that does not correspond to any network interfece. Addresses that
===========================================================================
are already in use will always fail, and unsupported protocols will always BE
=============================================================================
silently skipped.
=================
Examples:
=========
bind 192.168.1.100 10.0.0.1 # listens on two specific IPv4 addresses
====================================================================
bind 127.0.0.1 ::1 # listens on loopback IPv4 and IPv6
======================================================
bind \* -::\* # like the default, all available interfaces
==========================================================
\~\~\~ WARNING \~\~\~ If the computer running Redis is directly exposed to the
==============================================================================
internet, binding to all the interfaces is dangerous and will expose the
========================================================================
instance to everybody on the internet. So by default we uncomment the
=====================================================================
following bind directive, that will force Redis to listen only on the
=====================================================================
IPv4 and IPv6 (if available) loopback interface addresses (this means Redis
===========================================================================
will only be able to accept client connections from the same host that it is
============================================================================
running on).
============
IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
======================================================================
JUST COMMENT OUT THE FOLLOWING LINE.
====================================
\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~\~
================================================================================================================================================
bind 127.0.0.1 -::1
===================
Protected mode is a layer of security protection, in order to avoid that
========================================================================
Redis instances left open on the internet are accessed and exploited.
=====================================================================
When protected mode is on and if:
=================================
1) The server is not binding explicitly to a set of addresses using the
=======================================================================
"bind" directive.
=================
2) No password is configured.
=============================
The server only accepts connections from clients connecting from the
====================================================================
IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
========================================================================
sockets.
========
By default protected mode is enabled. You should disable it only if
===================================================================
you are sure you want clients from other hosts to connect to Redis
==================================================================
even if no authentication is configured, nor a specific set of interfaces
=========================================================================
are explicitly listed using the "bind" directive.
=================================================
protected-mode no
Accept connections on the specified port, default is 6379 (IANA #815344).
=========================================================================
If port 0 is specified Redis will not listen on a TCP socket.
=============================================================
port 6379
TCP listen() backlog.
=====================
In high requests-per-second environments you need a high backlog in order
=========================================================================
to avoid slow clients connection issues. Note that the Linux kernel
===================================================================
will silently truncate it to the value of /proc/sys/net/core/somaxconn so
=========================================================================
make sure to raise both the value of somaxconn and tcp_max_syn_backlog
======================================================================
in order to get the desired effect.
===================================
tcp-backlog 511
Unix socket.
============
Specify the path for the Unix socket that will be used to listen for
====================================================================
incoming connections. There is no default, so Redis will not listen
===================================================================
on a unix socket when not specified.
====================================
unixsocket /run/redis.sock
==========================
unixsocketperm 700
==================
Close the connection after a client is idle for N seconds (0 to disable)
========================================================================
timeout 0
TCP keepalive.
==============
If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
====================================================================
of communication. This is useful for two reasons:
=================================================
1) Detect dead peers.
=====================
2) Force network equipment in the middle to consider the connection to be
=========================================================================
alive.
======
On Linux, the specified value (in seconds) is the period used to send ACKs.
===========================================================================
Note that to close the connection the double of the time is needed.
===================================================================
On other kernels the period depends on the kernel configuration.
================================================================
A reasonable value for this option is 300 seconds, which is the new
===================================================================
Redis default starting with Redis 3.2.1.
========================================
tcp-keepalive 300
################################# TLS/SSL #####################################
By default, TLS/SSL is disabled. To enable it, the "tls-port" configuration
===========================================================================
directive can be used to define TLS-listening ports. To enable TLS on the
=========================================================================
default port, use:
==================
port 0
======
tls-port 6379
=============
Configure a X.509 certificate and private key to use for authenticating the
===========================================================================
server to connected clients, masters or cluster peers. These files should be
============================================================================
PEM formatted.
==============
tls-cert-file redis.crt
=======================
tls-key-file redis.key
======================
If the key file is encrypted using a passphrase, it can be included here
========================================================================
as well.
========
tls-key-file-pass secret
========================
Normally Redis uses the same certificate for both server functions (accepting
=============================================================================
connections) and client functions (replicating from a master, establishing
==========================================================================
cluster bus connections, etc.).
===============================
Sometimes certificates are issued with attributes that designate them as
========================================================================
client-only or server-only certificates. In that case it may be desired to use
==============================================================================
different certificates for incoming (server) and outgoing (client)
==================================================================
connections. To do that, use the following directives:
======================================================
tls-client-cert-file client.crt
===============================
tls-client-key-file client.key
==============================
If the key file is encrypted using a passphrase, it can be included here
========================================================================
as well.
========
tls-client-key-file-pass secret
===============================
Configure a DH parameters file to enable Diffie-Hellman (DH) key exchange:
==========================================================================
tls-dh-params-file redis.dh
===========================
Configure a CA certificate(s) bundle or directory to authenticate TLS/SSL
=========================================================================
clients and peers. Redis requires an explicit configuration of at least one
===========================================================================
of these, and will not implicitly use the system wide configuration.
====================================================================
tls-ca-cert-file ca.crt
=======================
tls-ca-cert-dir /etc/ssl/certs
==============================
By default, clients (including replica servers) on a TLS port are required
==========================================================================
to authenticate using valid client side certificates.
=====================================================
If "no" is specified, client certificates are not required and not accepted.
============================================================================
If "optional" is specified, client certificates are accepted and must be
========================================================================
valid if provided, but are not required.
========================================
tls-auth-clients no
===================
tls-auth-clients optional
=========================
By default, a Redis replica does not attempt to establish a TLS connection
==========================================================================
with its master.
================
Use the following directive to enable TLS on replication links.
===============================================================
tls-replication yes
===================
By default, the Redis Cluster bus uses a plain TCP connection. To enable
========================================================================
TLS for the bus protocol, use the following directive:
======================================================
tls-cluster yes
===============
By default, only TLSv1.2 and TLSv1.3 are enabled and it is highly recommended
=============================================================================
that older formally deprecated versions are kept disabled to reduce the attack surface.
=======================================================================================
You can explicitly specify TLS versions to support.
===================================================
Allowed values are case insensitive and include "TLSv1", "TLSv1.1", "TLSv1.2",
==============================================================================
"TLSv1.3" (OpenSSL \>= 1.1.1) or any combination.
=================================================
To enable only TLSv1.2 and TLSv1.3, use:
========================================
tls-protocols "TLSv1.2 TLSv1.3"
===============================
Configure allowed ciphers. See the ciphers(1ssl) manpage for more information
=============================================================================
about the syntax of this string.
================================
Note: this configuration applies only to \<= TLSv1.2.
=====================================================
tls-ciphers DEFAULT:!MEDIUM
===========================
Configure allowed TLSv1.3 ciphersuites. See the ciphers(1ssl) manpage for more
==============================================================================
information about the syntax of this string, and specifically for TLSv1.3
=========================================================================
ciphersuites.
=============
tls-ciphersuites TLS_CHACHA20_POLY1305_SHA256
=============================================
When choosing a cipher, use the server's preference instead of the client
=========================================================================
preference. By default, the server follows the client's preference.
===================================================================
tls-prefer-server-ciphers yes
=============================
By default, TLS session caching is enabled to allow faster and less expensive
=============================================================================
reconnections by clients that support it. Use the following directive to disable
================================================================================
caching.
========
tls-session-caching no
======================
Change the default number of TLS sessions cached. A zero value sets the cache
=============================================================================
to unlimited size. The default size is 20480.
=============================================
tls-session-cache-size 5000
===========================
Change the default timeout of cached TLS sessions. The default timeout is 300
=============================================================================
seconds.
========
tls-session-cache-timeout 60
============================
################################# GENERAL #####################################
By default Redis does not run as a daemon. Use 'yes' if you need it.
====================================================================
Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
============================================================================
When Redis is supervised by upstart or systemd, this parameter has no impact.
=============================================================================
daemonize no
If you run Redis from upstart or systemd, Redis can interact with your
======================================================================
supervision tree. Options:
==========================
supervised no - no supervision interaction
==========================================
supervised upstart - signal upstart by putting Redis into SIGSTOP mode
======================================================================
requires "expect stop" in your upstart job config
=================================================
supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
========================================================================
on startup, and updating Redis status on a regular
==================================================
basis.
======
supervised auto - detect upstart or systemd method based on
===========================================================
UPSTART_JOB or NOTIFY_SOCKET environment variables
==================================================
Note: these supervision methods only signal "process is ready."
===============================================================
They do not enable continuous pings back to your supervisor.
============================================================
The default is "no". To run under upstart/systemd, you can simply uncomment
===========================================================================
the line below:
===============
supervised auto
===============
If a pid file is specified, Redis writes it where specified at startup
======================================================================
and removes it at exit.
=======================
When the server runs non daemonized, no pid file is created if none is
======================================================================
specified in the configuration. When the server is daemonized, the pid file
===========================================================================
is used even if not specified, defaulting to "/var/run/redis.pid".
==================================================================
Creating a pid file is best effort: if Redis is not able to create it
=====================================================================
nothing bad happens, the server will start and run normally.
============================================================
Note that on modern Linux systems "/run/redis.pid" is more conforming
=====================================================================
and should be used instead.
===========================
pidfile /var/run/redis_6379.pid
Specify the server verbosity level.
===================================
This can be one of:
===================
debug (a lot of information, useful for development/testing)
============================================================
verbose (many rarely useful info, but not a mess like the debug level)
======================================================================
notice (moderately verbose, what you want in production probably)
=================================================================
warning (only very important / critical messages are logged)
============================================================
loglevel notice
Specify the log file name. Also the empty string can be used to force
=====================================================================
Redis to log on the standard output. Note that if you use standard
==================================================================
output for logging but daemonize, logs will be sent to /dev/null
================================================================
logfile ""
To enable logging to the system logger, just set 'syslog-enabled' to yes,
=========================================================================
and optionally update the other syslog parameters to suit your needs.
=====================================================================
syslog-enabled no
=================
Specify the syslog identity.
============================
syslog-ident redis
==================
Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
===================================================================
syslog-facility local0
======================
To disable the built in crash log, which will possibly produce cleaner core
===========================================================================
dumps when they are needed, uncomment the following:
====================================================
crash-log-enabled no
====================
To disable the fast memory check that's run as part of the crash log, which
===========================================================================
will possibly let redis terminate sooner, uncomment the following:
==================================================================
crash-memcheck-enabled no
=========================
Set the number of databases. The default database is DB 0, you can select
=========================================================================
a different one on a per-connection basis using SELECT \<dbid\> where
=====================================================================
dbid is a number between 0 and 'databases'-1
============================================
databases 16
By default Redis shows an ASCII art logo only when started to log to the
========================================================================
standard output and if the standard output is a TTY and syslog logging is
=========================================================================
disabled. Basically this means that normally a logo is displayed only in
========================================================================
interactive sessions.
=====================
However it is possible to force the pre-4.0 behavior and always show a
======================================================================
ASCII art logo in startup logs by setting the following option to yes.
======================================================================
always-show-logo no
By default, Redis modifies the process title (as seen in 'top' and 'ps') to
===========================================================================
provide some runtime information. It is possible to disable this and leave
==========================================================================
the process name as executed by setting the following to no.
============================================================
set-proc-title yes
When changing the process title, Redis uses the following template to construct
===============================================================================
the modified title.
===================
Template variables are specified in curly brackets. The following variables are
===============================================================================
supported:
==========
{title} Name of process as executed if parent, or type of child process.
========================================================================
{listen-addr} Bind address or '\*' followed by TCP or TLS port listening on, or
===============================================================================
Unix socket if only that's available.
=====================================
{server-mode} Special mode, i.e. "\[sentinel\]" or "\[cluster\]".
=================================================================
{port} TCP port listening on, or 0.
===================================
{tls-port} TLS port listening on, or 0.
=======================================
{unixsocket} Unix domain socket listening on, or "".
====================================================
{config-file} Name of configuration file used.
==============================================
proc-title-template "{title} {listen-addr} {server-mode}"
################################ SNAPSHOTTING ################################
Save the DB to disk.
====================
save \<seconds\> \<changes\>
============================
Redis will save the DB if both the given number of seconds and the given
========================================================================
number of write operations against the DB occurred.
===================================================
Snapshotting can be completely disabled with a single empty string argument
===========================================================================
as in following example:
========================
save ""
=======
Unless specified otherwise, by default Redis will save the DB:
==============================================================
\* After 3600 seconds (an hour) if at least 1 key changed
=========================================================
\* After 300 seconds (5 minutes) if at least 100 keys changed
=============================================================
\* After 60 seconds if at least 10000 keys changed
==================================================
You can set these explicitly by uncommenting the three following lines.
=======================================================================
save 3600 1
===========
save 300 100
============
save 60 10000
=============
By default Redis will stop accepting writes if RDB snapshots are enabled
========================================================================
(at least one save point) and the latest background save failed.
================================================================
This will make the user aware (in a hard way) that data is not persisting
=========================================================================
on disk properly, otherwise chances are that no one will notice and some
========================================================================
disaster will happen.
=====================
If the background saving process will start working again Redis will
====================================================================
automatically allow writes again.
=================================
However if you have setup your proper monitoring of the Redis server
====================================================================
and persistence, you may want to disable this feature so that Redis will
========================================================================
continue to work as usual even if there are problems with disk,
===============================================================
permissions, and so forth.
==========================
stop-writes-on-bgsave-error yes
Compress string objects using LZF when dump .rdb databases?
===========================================================
By default compression is enabled as it's almost always a win.
==============================================================
If you want to save some CPU in the saving child set it to 'no' but
===================================================================
the dataset will likely be bigger if you have compressible values or keys.
==========================================================================
rdbcompression yes
Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
=========================================================================
This makes the format more resistant to corruption but there is a performance
=============================================================================
hit to pay (around 10%) when saving and loading RDB files, so you can disable it
================================================================================
for maximum performances.
=========================
RDB files created with checksum disabled have a checksum of zero that will
==========================================================================
tell the loading code to skip the check.
========================================
rdbchecksum yes
Enables or disables full sanitation checks for ziplist and listpack etc when
============================================================================
loading an RDB or RESTORE payload. This reduces the chances of a assertion or
=============================================================================
crash later on while processing commands.
=========================================
Options:
========
no - Never perform full sanitation
==================================
yes - Always perform full sanitation
====================================
clients - Perform full sanitation only for user connections.
============================================================
Excludes: RDB files, RESTORE commands received from the master
==============================================================
connection, and client connections which have the
=================================================
skip-sanitize-payload ACL flag.
===============================
The default should be 'clients' but since it currently affects cluster
======================================================================
resharding via MIGRATE, it is temporarily set to 'no' by default.
=================================================================
sanitize-dump-payload no
========================
The filename where to dump the DB
=================================
dbfilename dump.rdb
Remove RDB files used by replication in instances without persistence
=====================================================================
enabled. By default this option is disabled, however there are environments
===========================================================================
where for regulations or other security concerns, RDB files persisted on
========================================================================
disk by masters in order to feed replicas, or stored on disk by replicas
========================================================================
in order to load them for the initial synchronization, should be deleted
========================================================================
ASAP. Note that this option ONLY WORKS in instances that have both AOF
======================================================================
and RDB persistence disabled, otherwise is completely ignored.
==============================================================
An alternative (and sometimes better) way to obtain the same effect is
======================================================================
to use diskless replication on both master and replicas instances. However
==========================================================================
in the case of replicas, diskless is not always an option.
==========================================================
rdb-del-sync-files no
The working directory.
======================
The DB will be written inside this directory, with the filename specified
=========================================================================
above using the 'dbfilename' configuration directive.
=====================================================
The Append Only File will also be created inside this directory.
================================================================
Note that you must specify a directory here, not a file name.
=============================================================
dir ./
################################# REPLICATION #################################
Master-Replica replication. Use replicaof to make a Redis instance a copy of
============================================================================
another Redis server. A few things to understand ASAP about Redis replication.
==============================================================================
+------------------+ +---------------+
======================================
\| Master \| ---\> \| Replica \|
================================
\| (receive writes) \| \| (exact copy) \|
=========================================
+------------------+ +---------------+
======================================
1) Redis replication is asynchronous, but you can configure a master to
=======================================================================
stop accepting writes if it appears to be not connected with at least
=====================================================================
a given number of replicas.
===========================
2) Redis replicas are able to perform a partial resynchronization with the
==========================================================================
master if the replication link is lost for a relatively small amount of
=======================================================================
time. You may want to configure the replication backlog size (see the next
==========================================================================
sections of this file) with a sensible value depending on your needs.
=====================================================================
3) Replication is automatic and does not need user intervention. After a
========================================================================
network partition replicas automatically try to reconnect to masters
====================================================================
and resynchronize with them.
============================
replicaof \<masterip\> \<masterport\>
=====================================
If the master is password protected (using the "requirepass" configuration
==========================================================================
directive below) it is possible to tell the replica to authenticate before
==========================================================================
starting the replication synchronization process, otherwise the master will
===========================================================================
refuse the replica request.
===========================
masterauth \<master-password\>
==============================
However this is not enough if you are using Redis ACLs (for Redis version
=========================================================================
6 or greater), and the default user is not capable of running the PSYNC
=======================================================================
command and/or other commands needed for replication. In this case it's
=======================================================================
better to configure a special user to use with replication, and specify the
===========================================================================
masteruser configuration as such:
=================================
masteruser \<username\>
=======================
When masteruser is specified, the replica will authenticate against its
=======================================================================
master using the new AUTH form: AUTH \<username\> \<password\>.
===============================================================
When a replica loses its connection with the master, or when the replication
============================================================================
is still in progress, the replica can act in two different ways:
================================================================
1) if replica-serve-stale-data is set to 'yes' (the default) the replica will
=============================================================================
still reply to client requests, possibly with out of date data, or the
======================================================================
data set may just be empty if this is the first synchronization.
================================================================
2) If replica-serve-stale-data is set to 'no' the replica will reply with
=========================================================================
an error "SYNC with master in progress" to all commands except:
===============================================================
INFO, REPLICAOF, AUTH, PING, SHUTDOWN, REPLCONF, ROLE, CONFIG, SUBSCRIBE,
=========================================================================
UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE, PUBLISH, PUBSUB, COMMAND, POST,
======================================================================
HOST and LATENCY.
=================
replica-serve-stale-data yes
You can configure a replica instance to accept writes or not. Writing against
=============================================================================
a replica instance may be useful to store some ephemeral data (because data
===========================================================================
written on a replica will be easily deleted after resync with the master) but
=============================================================================
may also cause problems if clients are writing to it because of a
=================================================================
misconfiguration.
=================
Since Redis 2.6 by default replicas are read-only.
==================================================
Note: read only replicas are not designed to be exposed to untrusted clients
============================================================================
on the internet. It's just a protection layer against misuse of the instance.
=============================================================================
Still a read only replica exports by default all the administrative commands
============================================================================
such as CONFIG, DEBUG, and so forth. To a limited extent you can improve
========================================================================
security of read only replicas using 'rename-command' to shadow all the
=======================================================================
administrative / dangerous commands.
====================================
replica-read-only yes
Replication SYNC strategy: disk or socket.
==========================================
New replicas and reconnecting replicas that are not able to continue the
========================================================================
replication process just receiving differences, need to do what is called a
===========================================================================
"full synchronization". An RDB file is transmitted from the master to the
=========================================================================
replicas.
=========
The transmission can happen in two different ways:
==================================================
1) Disk-backed: The Redis master creates a new process that writes the RDB
==========================================================================
file on disk. Later the file is transferred by the parent
=========================================================
process to the replicas incrementally.
======================================
2) Diskless: The Redis master creates a new process that directly writes the
============================================================================
RDB file to replica sockets, without touching the disk at all.
==============================================================
With disk-backed replication, while the RDB file is generated, more replicas
============================================================================
can be queued and served with the RDB file as soon as the current child
=======================================================================
producing the RDB file finishes its work. With diskless replication instead
===========================================================================
once the transfer starts, new replicas arriving will be queued and a new
========================================================================
transfer will start when the current one terminates.
====================================================
When diskless replication is used, the master waits a configurable amount of
============================================================================
time (in seconds) before starting the transfer in the hope that multiple
========================================================================
replicas will arrive and the transfer can be parallelized.
==========================================================
With slow disks and fast (large bandwidth) networks, diskless replication
=========================================================================
works better.
=============
repl-diskless-sync no
When diskless replication is enabled, it is possible to configure the delay
===========================================================================
the server waits in order to spawn the child that transfers the RDB via socket
==============================================================================
to the replicas.
================
This is important since once the transfer starts, it is not possible to serve
=============================================================================
new replicas arriving, that will be queued for the next RDB transfer, so the
============================================================================
server waits a delay in order to let more replicas arrive.
==========================================================
The delay is specified in seconds, and by default is 5 seconds. To disable
==========================================================================
it entirely just set it to 0 seconds and the transfer will start ASAP.
======================================================================
repl-diskless-sync-delay 5
-----------------------------------------------------------------------------
=============================================================================
WARNING: RDB diskless load is experimental. Since in this setup the replica
===========================================================================
does not immediately store an RDB on disk, it may cause data loss during
========================================================================
failovers. RDB diskless load + Redis modules not handling I/O reads may also
============================================================================
cause Redis to abort in case of I/O errors during the initial synchronization
=============================================================================
stage with the master. Use only if you know what you are doing.
===============================================================
-----------------------------------------------------------------------------
=============================================================================
Replica can load the RDB it reads from the replication link directly from the
=============================================================================
socket, or store the RDB to a file and read that file after it was completely
=============================================================================
received from the master.
=========================
In many cases the disk is slower than the network, and storing and loading
==========================================================================
the RDB file may increase replication time (and even increase the master's
==========================================================================
Copy on Write memory and salve buffers).
========================================
However, parsing the RDB file directly from the socket may mean that we have
============================================================================
to flush the contents of the current database before the full rdb was
=====================================================================
received. For this reason we have the following options:
========================================================
"disabled" - Don't use diskless load (store the rdb file to the disk first)
===========================================================================
"on-empty-db" - Use diskless load only when it is completely safe.
==================================================================
"swapdb" - Keep a copy of the current db contents in RAM while parsing
======================================================================
the data directly from the socket. note that this requires
==========================================================
sufficient memory, if you don't have it, you risk an OOM kill.
==============================================================
repl-diskless-load disabled
Replicas send PINGs to server in a predefined interval. It's possible to
========================================================================
change this interval with the repl_ping_replica_period option. The default
==========================================================================
value is 10 seconds.
====================
repl-ping-replica-period 10
===========================
The following option sets the replication timeout for:
======================================================
1) Bulk transfer I/O during SYNC, from the point of view of replica.
====================================================================
2) Master timeout from the point of view of replicas (data, pings).
===================================================================
3) Replica timeout from the point of view of masters (REPLCONF ACK pings).
==========================================================================
It is important to make sure that this value is greater than the value
======================================================================
specified for repl-ping-replica-period otherwise a timeout will be detected
===========================================================================
every time there is low traffic between the master and the replica. The default
===============================================================================
value is 60 seconds.
====================
repl-timeout 60
===============
Disable TCP_NODELAY on the replica socket after SYNC?
=====================================================
If you select "yes" Redis will use a smaller number of TCP packets and
======================================================================
less bandwidth to send data to replicas. But this can add a delay for
=====================================================================
the data to appear on the replica side, up to 40 milliseconds with
==================================================================
Linux kernels using a default configuration.
============================================
If you select "no" the delay for data to appear on the replica side will
========================================================================
be reduced but more bandwidth will be used for replication.
===========================================================
By default we optimize for low latency, but in very high traffic conditions
===========================================================================
or when the master and replicas are many hops away, turning this to "yes" may
=============================================================================
be a good idea.
===============
repl-disable-tcp-nodelay no
Set the replication backlog size. The backlog is a buffer that accumulates
==========================================================================
replica data when replicas are disconnected for some time, so that when a
=========================================================================
replica wants to reconnect again, often a full resync is not needed, but a
==========================================================================
partial resync is enough, just passing the portion of data the replica
======================================================================
missed while disconnected.
==========================
The bigger the replication backlog, the longer the replica can endure the
=========================================================================
disconnect and later be able to perform a partial resynchronization.
====================================================================
The backlog is only allocated if there is at least one replica connected.
=========================================================================
repl-backlog-size 1mb
=====================
After a master has no connected replicas for some time, the backlog will be
===========================================================================
freed. The following option configures the amount of seconds that need to
=========================================================================
elapse, starting from the time the last replica disconnected, for the backlog
=============================================================================
buffer to be freed.
===================
Note that replicas never free the backlog for timeout, since they may be
========================================================================
promoted to masters later, and should be able to correctly "partially
=====================================================================
resynchronize" with other replicas: hence they should always accumulate backlog.
================================================================================
A value of 0 means to never release the backlog.
================================================
repl-backlog-ttl 3600
=====================
The replica priority is an integer number published by Redis in the INFO
========================================================================
output. It is used by Redis Sentinel in order to select a replica to promote
============================================================================
into a master if the master is no longer working correctly.
===========================================================
A replica with a low priority number is considered better for promotion, so
===========================================================================
for instance if there are three replicas with priority 10, 100, 25 Sentinel
===========================================================================
will pick the one with priority 10, that is the lowest.
=======================================================
However a special priority of 0 marks the replica as not able to perform the
============================================================================
role of master, so a replica with priority of 0 will never be selected by
=========================================================================
Redis Sentinel for promotion.
=============================
By default the priority is 100.
===============================
replica-priority 100
-----------------------------------------------------------------------------
=============================================================================
By default, Redis Sentinel includes all replicas in its reports. A replica
==========================================================================
can be excluded from Redis Sentinel's announcements. An unannounced replica
===========================================================================
will be ignored by the 'sentinel replicas \<master\>' command and won't be
==========================================================================
exposed to Redis Sentinel's clients.
====================================
This option does not change the behavior of replica-priority. Even with
=======================================================================
replica-announced set to 'no', the replica can be promoted to master. To
========================================================================
prevent this behavior, set replica-priority to 0.
=================================================
replica-announced yes
=====================
It is possible for a master to stop accepting writes if there are less than
===========================================================================
N replicas connected, having a lag less or equal than M seconds.
================================================================
The N replicas need to be in "online" state.
============================================
The lag in seconds, that must be \<= the specified value, is calculated from
============================================================================
the last ping received from the replica, that is usually sent every second.
===========================================================================
This option does not GUARANTEE that N replicas will accept the write, but
=========================================================================
will limit the window of exposure for lost writes in case not enough replicas
=============================================================================
are available, to the specified number of seconds.
==================================================
For example to require at least 3 replicas with a lag \<= 10 seconds use:
=========================================================================
min-replicas-to-write 3
=======================
min-replicas-max-lag 10
=======================
Setting one or the other to 0 disables the feature.
===================================================
By default min-replicas-to-write is set to 0 (feature disabled) and
===================================================================
min-replicas-max-lag is set to 10.
==================================
A Redis master is able to list the address and port of the attached
===================================================================
replicas in different ways. For example the "INFO replication" section
======================================================================
offers this information, which is used, among other tools, by
=============================================================
Redis Sentinel in order to discover replica instances.
======================================================
Another place where this info is available is in the output of the
==================================================================
"ROLE" command of a master.
===========================
The listed IP address and port normally reported by a replica is
================================================================
obtained in the following way:
==============================
IP: The address is auto detected by checking the peer address
=============================================================
of the socket used by the replica to connect with the master.
=============================================================
Port: The port is communicated by the replica during the replication
====================================================================
handshake, and is normally the port that the replica is using to
================================================================
listen for connections.
=======================
However when port forwarding or Network Address Translation (NAT) is
====================================================================
used, the replica may actually be reachable via different IP and port
=====================================================================
pairs. The following two options can be used by a replica in order to
=====================================================================
report to its master a specific set of IP and port, so that both INFO
=====================================================================
and ROLE will report those values.
==================================
There is no need to use both the options if you need to override just
=====================================================================
the port or the IP address.
===========================
replica-announce-ip 5.5.5.5
===========================
replica-announce-port 1234
==========================
############################### KEYS TRACKING #################################
Redis implements server assisted support for client side caching of values.
===========================================================================
This is implemented using an invalidation table that remembers, using
=====================================================================
a radix key indexed by key name, what clients have which keys. In turn
======================================================================
this is used in order to send invalidation messages to clients. Please
======================================================================
check this page to understand more about the feature:
=====================================================
https://redis.io/topics/client-side-caching
===========================================
When tracking is enabled for a client, all the read only queries are assumed
============================================================================
to be cached: this will force Redis to store information in the invalidation
============================================================================
table. When keys are modified, such information is flushed away, and
====================================================================
invalidation messages are sent to the clients. However if the workload is
=========================================================================
heavily dominated by reads, Redis could use more and more memory in order
=========================================================================
to track the keys fetched by many clients.
==========================================
For this reason it is possible to configure a maximum fill value for the
========================================================================
invalidation table. By default it is set to 1M of keys, and once this limit
===========================================================================
is reached, Redis will start to evict keys in the invalidation table
====================================================================
even if they were not modified, just to reclaim memory: this will in turn
=========================================================================
force the clients to invalidate the cached values. Basically the table
======================================================================
maximum size is a trade off between the memory you want to spend server
=======================================================================
side to track information about who cached what, and the ability of clients
===========================================================================
to retain cached objects in memory.
===================================
If you set the value to 0, it means there are no limits, and Redis will
=======================================================================
retain as many keys as needed in the invalidation table.
========================================================
In the "stats" INFO section, you can find information about the number of
=========================================================================
keys in the invalidation table at every given moment.
=====================================================
Note: when key tracking is used in broadcasting mode, no memory is used
=======================================================================
in the server side so this setting is useless.
==============================================
tracking-table-max-keys 1000000
===============================
################################## SECURITY ###################################
Warning: since Redis is pretty fast, an outside user can try up to
==================================================================
1 million passwords per second against a modern box. This means that you
========================================================================
should use very strong passwords, otherwise they will be very easy to break.
============================================================================
Note that because the password is really a shared secret between the client
===========================================================================
and the server, and should not be memorized by any human, the password
======================================================================
can be easily a long string from /dev/urandom or whatever, so by using a
========================================================================
long and unguessable password no brute force attack will be possible.
=====================================================================
Redis ACL users are defined in the following format:
====================================================
user \<username\> ... acl rules ...
===================================
For example:
============
user worker +@list +@connection \~jobs:\* on \>ffa9203c493aa99
==============================================================
The special username "default" is used for new connections. If this user
========================================================================
has the "nopass" rule, then new connections will be immediately authenticated
=============================================================================
as the "default" user without the need of any password provided via the
=======================================================================
AUTH command. Otherwise if the "default" user is not flagged with "nopass"
==========================================================================
the connections will start in not authenticated state, and will require
=======================================================================
AUTH (or the HELLO command AUTH option) in order to be authenticated and
========================================================================
start to work.
==============
The ACL rules that describe what a user can do are the following:
=================================================================
on Enable the user: it is possible to authenticate as this user.
================================================================
off Disable the user: it's no longer possible to authenticate
=============================================================
with this user, however the already authenticated connections
=============================================================
will still work.
================
skip-sanitize-payload RESTORE dump-payload sanitation is skipped.
=================================================================
sanitize-payload RESTORE dump-payload is sanitized (default).
=============================================================
+\<command\> Allow the execution of that command
================================================
-\<command\> Disallow the execution of that command
===================================================
+@\<category\> Allow the execution of all the commands in such category
=======================================================================
with valid categories are like @admin, @set, @sortedset, ...
============================================================
and so forth, see the full list in the server.c file where
==========================================================
the Redis command table is described and defined.
=================================================
The special category @all means all the commands, but currently
===============================================================
present in the server, and that will be loaded in the future
============================================================
via modules.
============
+\<command\>\|subcommand Allow a specific subcommand of an otherwise
====================================================================
disabled command. Note that this form is not
============================================
allowed as negative like -DEBUG\|SEGFAULT, but
==============================================
only additive starting with "+".
================================
allcommands Alias for +@all. Note that it implies the ability to execute
========================================================================
all the future commands loaded via the modules system.
======================================================
nocommands Alias for -@all.
===========================
\~\<pattern\> Add a pattern of keys that can be mentioned as part of
====================================================================
commands. For instance \~\* allows all the keys. The pattern
============================================================
is a glob-style pattern like the one of KEYS.
=============================================
It is possible to specify multiple patterns.
============================================
allkeys Alias for \~\*
======================
resetkeys Flush the list of allowed keys patterns.
==================================================
\&\<pattern\> Add a glob-style pattern of Pub/Sub channels that can be
======================================================================
accessed by the user. It is possible to specify multiple channel
================================================================
patterns.
=========
allchannels Alias for \&\*
==========================
resetchannels Flush the list of allowed channel patterns.
=========================================================
\>\<password\> Add this password to the list of valid password for the user.
============================================================================
For example \>mypass will add "mypass" to the list.
===================================================
This directive clears the "nopass" flag (see later).
====================================================
\<\<password\> Remove this password from the list of valid passwords.
=====================================================================
nopass All the set passwords of the user are removed, and the user
==================================================================
is flagged as requiring no password: it means that every
========================================================
password will work against this user. If this directive is
==========================================================
used for the default user, every new connection will be
=======================================================
immediately authenticated with the default user without
=======================================================
any explicit AUTH command required. Note that the "resetpass"
=============================================================
directive will clear this condition.
====================================
resetpass Flush the list of allowed passwords. Moreover removes the
===================================================================
"nopass" status. After "resetpass" the user has no associated
=============================================================
passwords and there is no way to authenticate without adding
============================================================
some password (or setting it as "nopass" later).
================================================
reset Performs the following actions: resetpass, resetkeys, off,
================================================================
-@all. The user returns to the same state it has immediately
============================================================
after its creation.
===================
ACL rules can be specified in any order: for instance you can start with
========================================================================
passwords, then flags, or key patterns. However note that the additive
======================================================================
and subtractive rules will CHANGE MEANING depending on the ordering.
====================================================================
For instance see the following example:
=======================================
user alice on +@all -DEBUG \~\* \>somepassword
==============================================
This will allow "alice" to use all the commands with the exception of the
=========================================================================
DEBUG command, since +@all added all the commands to the set of the commands
============================================================================
alice can use, and later DEBUG was removed. However if we invert the order
==========================================================================
of two ACL rules the result will be different:
==============================================
user alice on -DEBUG +@all \~\* \>somepassword
==============================================
Now DEBUG was removed when alice had yet no commands in the set of allowed
==========================================================================
commands, later all the commands are added, so the user will be able to
=======================================================================
execute everything.
===================
Basically ACL rules are processed left-to-right.
================================================
For more information about ACL configuration please refer to
============================================================
the Redis web site at https://redis.io/topics/acl
=================================================
ACL LOG
=======
The ACL Log tracks failed commands and authentication events associated
=======================================================================
with ACLs. The ACL Log is useful to troubleshoot failed commands blocked
========================================================================
by ACLs. The ACL Log is stored in memory. You can reclaim memory with
=====================================================================
ACL LOG RESET. Define the maximum entry length of the ACL Log below.
====================================================================
acllog-max-len 128
Using an external ACL file
==========================
Instead of configuring users here in this file, it is possible to use
=====================================================================
a stand-alone file just listing users. The two methods cannot be mixed:
=======================================================================
if you configure users here and at the same time you activate the external
==========================================================================
ACL file, the server will refuse to start.
==========================================
The format of the external ACL user file is exactly the same as the
===================================================================
format that is used inside redis.conf to describe users.
========================================================
aclfile /etc/redis/users.acl
============================
IMPORTANT NOTE: starting with Redis 6 "requirepass" is just a compatibility
===========================================================================
layer on top of the new ACL system. The option effect will be just setting
==========================================================================
the password for the default user. Clients will still authenticate using
========================================================================
AUTH \<password\> as usually, or more explicitly with AUTH default \<password\>
===============================================================================
if they follow the new protocol: both will work.
================================================
The requirepass is not compatable with aclfile option and the ACL LOAD
======================================================================
command, these will cause requirepass to be ignored.
====================================================
requirepass huangge1199
New users are initialized with restrictive permissions by default, via the
==========================================================================
equivalent of this ACL rule 'off resetkeys -@all'. Starting with Redis 6.2, it
==============================================================================
is possible to manage access to Pub/Sub channels with ACL rules as well. The
============================================================================
default Pub/Sub channels permission if new users is controlled by the
=====================================================================
acl-pubsub-default configuration directive, which accepts one of these values:
==============================================================================
allchannels: grants access to all Pub/Sub channels
==================================================
resetchannels: revokes access to all Pub/Sub channels
=====================================================
To ensure backward compatibility while upgrading Redis 6.0, acl-pubsub-default
==============================================================================
defaults to the 'allchannels' permission.
=========================================
Future compatibility note: it is very likely that in a future version of Redis
==============================================================================
the directive's default of 'allchannels' will be changed to 'resetchannels' in
==============================================================================
order to provide better out-of-the-box Pub/Sub security. Therefore, it is
=========================================================================
recommended that you explicitly define Pub/Sub permissions for all users
========================================================================
rather then rely on implicit default values. Once you've set explicit
=====================================================================
Pub/Sub for all existing users, you should uncomment the following line.
========================================================================
acl-pubsub-default resetchannels
================================
Command renaming (DEPRECATED).
==============================
------------------------------------------------------------------------
========================================================================
WARNING: avoid using this option if possible. Instead use ACLs to remove
========================================================================
commands from the default user, and put them only in some admin user you
========================================================================
create for administrative purposes.
===================================
------------------------------------------------------------------------
========================================================================
It is possible to change the name of dangerous commands in a shared
===================================================================
environment. For instance the CONFIG command may be renamed into something
==========================================================================
hard to guess so that it will still be available for internal-use tools
=======================================================================
but not available for general clients.
======================================
Example:
========
rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
==============================================================
It is also possible to completely kill a command by renaming it into
====================================================================
an empty string:
================
rename-command CONFIG ""
========================
Please note that changing the name of commands that are logged into the
=======================================================================
AOF file or transmitted to replicas may cause problems.
=======================================================
################################### CLIENTS ####################################
Set the max number of connected clients at the same time. By default
====================================================================
this limit is set to 10000 clients, however if the Redis server is not
======================================================================
able to configure the process file limit to allow for the specified limit
=========================================================================
the max number of allowed clients is set to the current file limit
==================================================================
minus 32 (as Redis reserves a few file descriptors for internal uses).
======================================================================
Once the limit is reached Redis will close all the new connections sending
==========================================================================
an error 'max number of clients reached'.
=========================================
IMPORTANT: When Redis Cluster is used, the max number of connections is also
============================================================================
shared with the cluster bus: every node in the cluster will use two
===================================================================
connections, one incoming and another outgoing. It is important to size the
===========================================================================
limit accordingly in case of very large clusters.
=================================================
maxclients 10000
================
############################## MEMORY MANAGEMENT ################################
Set a memory usage limit to the specified amount of bytes.
==========================================================
When the memory limit is reached Redis will try to remove keys
==============================================================
according to the eviction policy selected (see maxmemory-policy).
=================================================================
If Redis can't remove keys according to the policy, or if the policy is
=======================================================================
set to 'noeviction', Redis will start to reply with errors to commands
======================================================================
that would use more memory, like SET, LPUSH, and so on, and will continue
=========================================================================
to reply to read-only commands like GET.
========================================
This option is usually useful when using Redis as an LRU or LFU cache, or to
============================================================================
set a hard memory limit for an instance (using the 'noeviction' policy).
========================================================================
WARNING: If you have replicas attached to an instance with maxmemory on,
========================================================================
the size of the output buffers needed to feed the replicas are subtracted
=========================================================================
from the used memory count, so that network problems / resyncs will
===================================================================
not trigger a loop where keys are evicted, and in turn the output
=================================================================
buffer of replicas is full with DELs of keys evicted triggering the deletion
============================================================================
of more keys, and so forth until the database is completely emptied.
====================================================================
In short... if you have replicas attached it is suggested that you set a lower
==============================================================================
limit for maxmemory so that there is some free RAM on the system for replica
============================================================================
output buffers (but this is not needed if the policy is 'noeviction').
======================================================================
maxmemory \<bytes\>
===================
MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
=====================================================================
is reached. You can select one from the following behaviors:
============================================================
volatile-lru -\> Evict using approximated LRU, only keys with an expire set.
============================================================================
allkeys-lru -\> Evict any key using approximated LRU.
=====================================================
volatile-lfu -\> Evict using approximated LFU, only keys with an expire set.
============================================================================
allkeys-lfu -\> Evict any key using approximated LFU.
=====================================================
volatile-random -\> Remove a random key having an expire set.
=============================================================
allkeys-random -\> Remove a random key, any key.
================================================
volatile-ttl -\> Remove the key with the nearest expire time (minor TTL)
========================================================================
noeviction -\> Don't evict anything, just return an error on write operations.
==============================================================================
LRU means Least Recently Used
=============================
LFU means Least Frequently Used
===============================
Both LRU, LFU and volatile-ttl are implemented using approximated
=================================================================
randomized algorithms.
======================
Note: with any of the above policies, when there are no suitable keys for
=========================================================================
eviction, Redis will return an error on write operations that require
=====================================================================
more memory. These are usually commands that create new keys, add data or
=========================================================================
modify existing keys. A few examples are: SET, INCR, HSET, LPUSH, SUNIONSTORE,
==============================================================================
SORT (due to the STORE argument), and EXEC (if the transaction includes any
===========================================================================
command that requires memory).
==============================
The default is:
===============
maxmemory-policy noeviction
===========================
LRU, LFU and minimal TTL algorithms are not precise algorithms but approximated
===============================================================================
algorithms (in order to save memory), so you can tune it for speed or
=====================================================================
accuracy. By default Redis will check five keys and pick the one that was
=========================================================================
used least recently, you can change the sample size using the following
=======================================================================
configuration directive.
========================
The default of 5 produces good enough results. 10 Approximates very closely
===========================================================================
true LRU but costs more CPU. 3 is faster but not very accurate.
===============================================================
maxmemory-samples 5
===================
Eviction processing is designed to function well with the default setting.
==========================================================================
If there is an unusually large amount of write traffic, this value may need to
==============================================================================
be increased. Decreasing this value may reduce latency at the risk of
=====================================================================
eviction processing effectiveness
=================================
0 = minimum latency, 10 = default, 100 = process without regard to latency
==========================================================================
maxmemory-eviction-tenacity 10
==============================
Starting from Redis 5, by default a replica will ignore its maxmemory setting
=============================================================================
(unless it is promoted to master after a failover or manually). It means
========================================================================
that the eviction of keys will be just handled by the master, sending the
=========================================================================
DEL commands to the replica as keys evict in the master side.
=============================================================
This behavior ensures that masters and replicas stay consistent, and is usually
===============================================================================
what you want, however if your replica is writable, or you want the replica
===========================================================================
to have a different memory setting, and you are sure all the writes performed
=============================================================================
to the replica are idempotent, then you may change this default (but be sure
============================================================================
to understand what you are doing).
==================================
Note that since the replica by default does not evict, it may end using more
============================================================================
memory than the one set via maxmemory (there are certain buffers that may
=========================================================================
be larger on the replica, or data structures may sometimes take more memory
===========================================================================
and so forth). So make sure you monitor your replicas and make sure they
========================================================================
have enough memory to never hit a real out-of-memory condition before the
=========================================================================
master hits the configured maxmemory setting.
=============================================
replica-ignore-maxmemory yes
============================
Redis reclaims expired keys in two ways: upon access when those keys are
========================================================================
found to be expired, and also in background, in what is called the
==================================================================
"active expire key". The key space is slowly and interactively scanned
======================================================================
looking for expired keys to reclaim, so that it is possible to free memory
==========================================================================
of keys that are expired and will never be accessed again in a short time.
==========================================================================
The default effort of the expire cycle will try to avoid having more than
=========================================================================
ten percent of expired keys still in memory, and will try to avoid consuming
============================================================================
more than 25% of total memory and to add latency to the system. However
=======================================================================
it is possible to increase the expire "effort" that is normally set to
======================================================================
"1", to a greater value, up to the value "10". At its maximum value the
=======================================================================
system will use more CPU, longer cycles (and technically may introduce
======================================================================
more latency), and will tolerate less already expired keys still present
========================================================================
in the system. It's a tradeoff between memory, CPU and latency.
===============================================================
active-expire-effort 1
======================
############################# LAZY FREEING ####################################
Redis has two primitives to delete keys. One is called DEL and is a blocking
============================================================================
deletion of the object. It means that the server stops processing new commands
==============================================================================
in order to reclaim all the memory associated with an object in a synchronous
=============================================================================
way. If the key deleted is associated with a small object, the time needed
==========================================================================
in order to execute the DEL command is very small and comparable to most other
==============================================================================
O(1) or O(log_N) commands in Redis. However if the key is associated with an
============================================================================
aggregated value containing millions of elements, the server can block for
==========================================================================
a long time (even seconds) in order to complete the operation.
==============================================================
For the above reasons Redis also offers non blocking deletion primitives
========================================================================
such as UNLINK (non blocking DEL) and the ASYNC option of FLUSHALL and
======================================================================
FLUSHDB commands, in order to reclaim memory in background. Those commands
==========================================================================
are executed in constant time. Another thread will incrementally free the
=========================================================================
object in the background as fast as possible.
=============================================
DEL, UNLINK and ASYNC option of FLUSHALL and FLUSHDB are user-controlled.
=========================================================================
It's up to the design of the application to understand when it is a good
========================================================================
idea to use one or the other. However the Redis server sometimes has to
=======================================================================
delete keys or flush the whole database as a side effect of other operations.
=============================================================================
Specifically Redis deletes objects independently of a user call in the
======================================================================
following scenarios:
====================
1) On eviction, because of the maxmemory and maxmemory policy configurations,
=============================================================================
in order to make room for new data, without going over the specified
====================================================================
memory limit.
=============
2) Because of expire: when a key with an associated time to live (see the
=========================================================================
EXPIRE command) must be deleted from memory.
============================================
3) Because of a side effect of a command that stores data on a key that may
===========================================================================
already exist. For example the RENAME command may delete the old key
====================================================================
content when it is replaced with another one. Similarly SUNIONSTORE
===================================================================
or SORT with STORE option may delete existing keys. The SET command
===================================================================
itself removes any old content of the specified key in order to replace
=======================================================================
it with the specified string.
=============================
4) During replication, when a replica performs a full resynchronization with
============================================================================
its master, the content of the whole database is removed in order to
====================================================================
load the RDB file just transferred.
===================================
In all the above cases the default is to delete objects in a blocking way,
==========================================================================
like if DEL was called. However you can configure each case specifically
========================================================================
in order to instead release memory in a non-blocking way like if UNLINK
=======================================================================
was called, using the following configuration directives.
=========================================================
lazyfree-lazy-eviction no
lazyfree-lazy-expire no
lazyfree-lazy-server-del no
replica-lazy-flush no
It is also possible, for the case when to replace the user code DEL calls
=========================================================================
with UNLINK calls is not easy, to modify the default behavior of the DEL
========================================================================
command to act exactly like UNLINK, using the following configuration
=====================================================================
directive:
==========
lazyfree-lazy-user-del no
FLUSHDB, FLUSHALL, and SCRIPT FLUSH support both asynchronous and synchronous
=============================================================================
deletion, which can be controlled by passing the \[SYNC\|ASYNC\] flags into the
===============================================================================
commands. When neither flag is passed, this directive will be used to determine
===============================================================================
if the data should be deleted asynchronously.
=============================================
lazyfree-lazy-user-flush no
################################ THREADED I/O #################################
Redis is mostly single threaded, however there are certain threaded
===================================================================
operations such as UNLINK, slow I/O accesses and other things that are
======================================================================
performed on side threads.
==========================
Now it is also possible to handle Redis clients socket reads and writes
=======================================================================
in different I/O threads. Since especially writing is so slow, normally
=======================================================================
Redis users use pipelining in order to speed up the Redis performances per
==========================================================================
core, and spawn multiple instances in order to scale more. Using I/O
====================================================================
threads it is possible to easily speedup two times Redis without resorting
==========================================================================
to pipelining nor sharding of the instance.
===========================================
By default threading is disabled, we suggest enabling it only in machines
=========================================================================
that have at least 4 or more cores, leaving at least one spare core.
====================================================================
Using more than 8 threads is unlikely to help much. We also recommend using
===========================================================================
threaded I/O only if you actually have performance problems, with Redis
=======================================================================
instances being able to use a quite big percentage of CPU time, otherwise
=========================================================================
there is no point in using this feature.
========================================
So for instance if you have a four cores boxes, try to use 2 or 3 I/O
=====================================================================
threads, if you have a 8 cores, try to use 6 threads. In order to
=================================================================
enable I/O threads use the following configuration directive:
=============================================================
io-threads 4
============
Setting io-threads to 1 will just use the main thread as usual.
===============================================================
When I/O threads are enabled, we only use threads for writes, that is
=====================================================================
to thread the write(2) syscall and transfer the client buffers to the
=====================================================================
socket. However it is also possible to enable threading of reads and
====================================================================
protocol parsing using the following configuration directive, by setting
========================================================================
it to yes:
==========
io-threads-do-reads no
======================
Usually threading reads doesn't help much.
==========================================
NOTE 1: This configuration directive cannot be changed at runtime via
=====================================================================
CONFIG SET. Aso this feature currently does not work when SSL is
================================================================
enabled.
========
NOTE 2: If you want to test the Redis speedup using redis-benchmark, make
=========================================================================
sure you also run the benchmark itself in threaded mode, using the
==================================================================
--threads option to match the number of Redis threads, otherwise you'll not
===========================================================================
be able to notice the improvements.
===================================
############################ KERNEL OOM CONTROL ##############################
On Linux, it is possible to hint the kernel OOM killer on what processes
========================================================================
should be killed first when out of memory.
==========================================
Enabling this feature makes Redis actively control the oom_score_adj value
==========================================================================
for all its processes, depending on their role. The default scores will
=======================================================================
attempt to have background child processes killed before all others, and
========================================================================
replicas killed before masters.
===============================
Redis supports three options:
=============================
no: Don't make changes to oom-score-adj (default).
==================================================
yes: Alias to "relative" see below.
===================================
absolute: Values in oom-score-adj-values are written as is to the kernel.
=========================================================================
relative: Values are used relative to the initial value of oom_score_adj when
=============================================================================
the server starts and are then clamped to a range of -1000 to 1000.
===================================================================
Because typically the initial value is 0, they will often match the
===================================================================
absolute values.
================
oom-score-adj no
When oom-score-adj is used, this directive controls the specific values used
============================================================================
for master, replica and background child processes. Values range -2000 to
=========================================================================
2000 (higher means more likely to be killed).
=============================================
Unprivileged processes (not root, and without CAP_SYS_RESOURCE capabilities)
============================================================================
can freely increase their value, but not decrease it below its initial
======================================================================
settings. This means that setting oom-score-adj to "relative" and setting the
=============================================================================
oom-score-adj-values to positive values will always succeed.
============================================================
oom-score-adj-values 0 200 800
#################### KERNEL transparent hugepage CONTROL ######################
Usually the kernel Transparent Huge Pages control is set to "madvise" or
========================================================================
or "never" by default (/sys/kernel/mm/transparent_hugepage/enabled), in which
=============================================================================
case this config has no effect. On systems in which it is set to "always",
==========================================================================
redis will attempt to disable it specifically for the redis process in order
============================================================================
to avoid latency problems specifically with fork(2) and CoW.
============================================================
If for some reason you prefer to keep it enabled, you can set this config to
============================================================================
"no" and the kernel global to "always".
=======================================
disable-thp yes
############################## APPEND ONLY MODE ###############################
By default Redis asynchronously dumps the dataset on disk. This mode is
=======================================================================
good enough in many applications, but an issue with the Redis process or
========================================================================
a power outage may result into a few minutes of writes lost (depending on
=========================================================================
the configured save points).
============================
The Append Only File is an alternative persistence mode that provides
=====================================================================
much better durability. For instance using the default data fsync policy
========================================================================
(see later in the config file) Redis can lose just one second of writes in a
============================================================================
dramatic event like a server power outage, or a single write if something
=========================================================================
wrong with the Redis process itself happens, but the operating system is
========================================================================
still running correctly.
========================
AOF and RDB persistence can be enabled at the same time without problems.
=========================================================================
If the AOF is enabled on startup Redis will load the AOF, that is the file
==========================================================================
with the better durability guarantees.
======================================
Please check https://redis.io/topics/persistence for more information.
======================================================================
appendonly no
The name of the append only file (default: "appendonly.aof")
============================================================
appendfilename "appendonly.aof"
The fsync() call tells the Operating System to actually write data on disk
==========================================================================
instead of waiting for more data in the output buffer. Some OS will really flush
================================================================================
data on disk, some other OS will just try to do it ASAP.
========================================================
Redis supports three different modes:
=====================================
no: don't fsync, just let the OS flush the data when it wants. Faster.
======================================================================
always: fsync after every write to the append only log. Slow, Safest.
=====================================================================
everysec: fsync only one time every second. Compromise.
=======================================================
The default is "everysec", as that's usually the right compromise between
=========================================================================
speed and data safety. It's up to you to understand if you can relax this to
============================================================================
"no" that will let the operating system flush the output buffer when
====================================================================
it wants, for better performances (but if you can live with the idea of
=======================================================================
some data loss consider the default persistence mode that's snapshotting),
==========================================================================
or on the contrary, use "always" that's very slow but a bit safer than
======================================================================
everysec.
=========
More details please check the following article:
================================================
http://antirez.com/post/redis-persistence-demystified.html
==========================================================
If unsure, use "everysec".
==========================
appendfsync always
==================
appendfsync everysec
appendfsync no
==============
When the AOF fsync policy is set to always or everysec, and a background
========================================================================
saving process (a background save or AOF log background rewriting) is
=====================================================================
performing a lot of I/O against the disk, in some Linux configurations
======================================================================
Redis may block too long on the fsync() call. Note that there is no fix for
===========================================================================
this currently, as even performing fsync in a different thread will block
=========================================================================
our synchronous write(2) call.
==============================
In order to mitigate this problem it's possible to use the following option
===========================================================================
that will prevent fsync() from being called in the main process while a
=======================================================================
BGSAVE or BGREWRITEAOF is in progress.
======================================
This means that while another child is saving, the durability of Redis is
=========================================================================
the same as "appendfsync none". In practical terms, this means that it is
=========================================================================
possible to lose up to 30 seconds of log in the worst scenario (with the
========================================================================
default Linux settings).
========================
If you have latency problems turn this to "yes". Otherwise leave it as
======================================================================
"no" that is the safest pick from the point of view of durability.
==================================================================
no-appendfsync-on-rewrite no
Automatic rewrite of the append only file.
==========================================
Redis is able to automatically rewrite the log file implicitly calling
======================================================================
BGREWRITEAOF when the AOF log size grows by the specified percentage.
=====================================================================
This is how it works: Redis remembers the size of the AOF file after the
========================================================================
latest rewrite (if no rewrite has happened since the restart, the size of
=========================================================================
the AOF at startup is used).
============================
This base size is compared to the current size. If the current size is
======================================================================
bigger than the specified percentage, the rewrite is triggered. Also
====================================================================
you need to specify a minimal size for the AOF file to be rewritten, this
=========================================================================
is useful to avoid rewriting the AOF file even if the percentage increase
=========================================================================
is reached but it is still pretty small.
========================================
Specify a percentage of zero in order to disable the automatic AOF
==================================================================
rewrite feature.
================
auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb
An AOF file may be found to be truncated at the end during the Redis
====================================================================
startup process, when the AOF data gets loaded back into memory.
================================================================
This may happen when the system where Redis is running
======================================================
crashes, especially when an ext4 filesystem is mounted without the
==================================================================
data=ordered option (however this can't happen when Redis itself
================================================================
crashes or aborts but the operating system still works correctly).
==================================================================
Redis can either exit with an error when this happens, or load as much
======================================================================
data as possible (the default now) and start if the AOF file is found
=====================================================================
to be truncated at the end. The following option controls this behavior.
========================================================================
If aof-load-truncated is set to yes, a truncated AOF file is loaded and
=======================================================================
the Redis server starts emitting a log to inform the user of the event.
=======================================================================
Otherwise if the option is set to no, the server aborts with an error
=====================================================================
and refuses to start. When the option is set to no, the user requires
=====================================================================
to fix the AOF file using the "redis-check-aof" utility before to restart
=========================================================================
the server.
===========
Note that if the AOF file will be found to be corrupted in the middle
=====================================================================
the server will still exit with an error. This option only applies when
=======================================================================
Redis will try to read more data from the AOF file but not enough bytes
=======================================================================
will be found.
==============
aof-load-truncated yes
When rewriting the AOF file, Redis is able to use an RDB preamble in the
========================================================================
AOF file for faster rewrites and recoveries. When this option is turned
=======================================================================
on the rewritten AOF file is composed of two different stanzas:
===============================================================
\[RDB file\]\[AOF tail\]
========================
When loading, Redis recognizes that the AOF file starts with the "REDIS"
========================================================================
string and loads the prefixed RDB file, then continues loading the AOF
======================================================================
tail.
=====
aof-use-rdb-preamble yes
################################ LUA SCRIPTING ###############################
Max execution time of a Lua script in milliseconds.
===================================================
If the maximum execution time is reached Redis will log that a script is
========================================================================
still in execution after the maximum allowed time and will start to
===================================================================
reply to queries with an error.
===============================
When a long running script exceeds the maximum execution time only the
======================================================================
SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be
========================================================================
used to stop a script that did not yet call any write commands. The second
==========================================================================
is the only way to shut down the server in the case a write command was
=======================================================================
already issued by the script but the user doesn't want to wait for the natural
==============================================================================
termination of the script.
==========================
Set it to 0 or a negative value for unlimited execution without warnings.
=========================================================================
lua-time-limit 5000
################################ REDIS CLUSTER ###############################
Normal Redis instances can't be part of a Redis Cluster; only nodes that are
============================================================================
started as cluster nodes can. In order to start a Redis instance as a
=====================================================================
cluster node enable the cluster support uncommenting the following:
===================================================================
cluster-enabled yes
===================
Every cluster node has a cluster configuration file. This file is not
=====================================================================
intended to be edited by hand. It is created and updated by Redis nodes.
========================================================================
Every Redis Cluster node requires a different cluster configuration file.
=========================================================================
Make sure that instances running in the same system do not have
===============================================================
overlapping cluster configuration file names.
=============================================
cluster-config-file nodes-6379.conf
===================================
Cluster node timeout is the amount of milliseconds a node must be unreachable
=============================================================================
for it to be considered in failure state.
=========================================
Most other internal time limits are a multiple of the node timeout.
===================================================================
cluster-node-timeout 15000
==========================
A replica of a failing master will avoid to start a failover if its data
========================================================================
looks too old.
==============
There is no simple way for a replica to actually have an exact measure of
=========================================================================
its "data age", so the following two checks are performed:
==========================================================
1) If there are multiple replicas able to failover, they exchange messages
==========================================================================
in order to try to give an advantage to the replica with the best
=================================================================
replication offset (more data from the master processed).
=========================================================
Replicas will try to get their rank by offset, and apply to the start
=====================================================================
of the failover a delay proportional to their rank.
===================================================
2) Every single replica computes the time of the last interaction with
======================================================================
its master. This can be the last ping or command received (if the master
========================================================================
is still in the "connected" state), or the time that elapsed since the
======================================================================
disconnection with the master (if the replication link is currently down).
==========================================================================
If the last interaction is too old, the replica will not try to failover
========================================================================
at all.
=======
The point "2" can be tuned by user. Specifically a replica will not perform
===========================================================================
the failover if, since the last interaction with the master, the time
=====================================================================
elapsed is greater than:
========================
(node-timeout \* cluster-replica-validity-factor) + repl-ping-replica-period
============================================================================
So for example if node-timeout is 30 seconds, and the cluster-replica-validity-factor
=====================================================================================
is 10, and assuming a default repl-ping-replica-period of 10 seconds, the
=========================================================================
replica will not try to failover if it was not able to talk with the master
===========================================================================
for longer than 310 seconds.
============================
A large cluster-replica-validity-factor may allow replicas with too old data to failover
========================================================================================
a master, while a too small value may prevent the cluster from being able to
============================================================================
elect a replica at all.
=======================
For maximum availability, it is possible to set the cluster-replica-validity-factor
===================================================================================
to a value of 0, which means, that replicas will always try to failover the
===========================================================================
master regardless of the last time they interacted with the master.
===================================================================
(However they'll always try to apply a delay proportional to their
==================================================================
offset rank).
=============
Zero is the only value able to guarantee that when all the partitions heal
==========================================================================
the cluster will always be able to continue.
============================================
cluster-replica-validity-factor 10
==================================
Cluster replicas are able to migrate to orphaned masters, that are masters
==========================================================================
that are left without working replicas. This improves the cluster ability
=========================================================================
to resist to failures as otherwise an orphaned master can't be failed over
==========================================================================
in case of failure if it has no working replicas.
=================================================
Replicas migrate to orphaned masters only if there are still at least a
=======================================================================
given number of other working replicas for their old master. This number
========================================================================
is the "migration barrier". A migration barrier of 1 means that a replica
=========================================================================
will migrate only if there is at least 1 other working replica for its master
=============================================================================
and so forth. It usually reflects the number of replicas you want for every
===========================================================================
master in your cluster.
=======================
Default is 1 (replicas migrate only if their masters remain with at least
=========================================================================
one replica). To disable migration just set it to a very large value or
=======================================================================
set cluster-allow-replica-migration to 'no'.
============================================
A value of 0 can be set but is useful only for debugging and dangerous
======================================================================
in production.
==============
cluster-migration-barrier 1
===========================
Turning off this option allows to use less automatic cluster configuration.
===========================================================================
It both disables migration to orphaned masters and migration from masters
=========================================================================
that became empty.
==================
Default is 'yes' (allow automatic migrations).
==============================================
cluster-allow-replica-migration yes
===================================
By default Redis Cluster nodes stop accepting queries if they detect there
==========================================================================
is at least a hash slot uncovered (no available node is serving it).
====================================================================
This way if the cluster is partially down (for example a range of hash slots
============================================================================
are no longer covered) all the cluster becomes, eventually, unavailable.
========================================================================
It automatically returns available as soon as all the slots are covered again.
==============================================================================
However sometimes you want the subset of the cluster which is working,
======================================================================
to continue to accept queries for the part of the key space that is still
=========================================================================
covered. In order to do so, just set the cluster-require-full-coverage
======================================================================
option to no.
=============
cluster-require-full-coverage yes
=================================
This option, when set to yes, prevents replicas from trying to failover its
===========================================================================
master during master failures. However the replica can still perform a
======================================================================
manual failover, if forced to do so.
====================================
This is useful in different scenarios, especially in the case of multiple
=========================================================================
data center operations, where we want one side to never be promoted if not
==========================================================================
in the case of a total DC failure.
==================================
cluster-replica-no-failover no
==============================
This option, when set to yes, allows nodes to serve read traffic while the
==========================================================================
the cluster is in a down state, as long as it believes it owns the slots.
=========================================================================
This is useful for two cases. The first case is for when an application
=======================================================================
doesn't require consistency of data during node failures or network partitions.
===============================================================================
One example of this is a cache, where as long as the node has the data it
=========================================================================
should be able to serve it.
===========================
The second use case is for configurations that don't meet the recommended
=========================================================================
three shards but want to enable cluster mode and scale later. A
===============================================================
master outage in a 1 or 2 shard configuration causes a read/write outage to the
===============================================================================
entire cluster without this option set, with it set there is only a write outage.
=================================================================================
Without a quorum of masters, slot ownership will not change automatically.
==========================================================================
cluster-allow-reads-when-down no
================================
In order to setup your cluster make sure to read the documentation
==================================================================
available at https://redis.io web site.
=======================================
########################## CLUSTER DOCKER/NAT support ########################
In certain deployments, Redis Cluster nodes address discovery fails, because
============================================================================
addresses are NAT-ted or because ports are forwarded (the typical case is
=========================================================================
Docker and other containers).
=============================
In order to make Redis Cluster working in such environments, a static
=====================================================================
configuration where each node knows its public address is needed. The
=====================================================================
following four options are used for this scope, and are:
========================================================
\* cluster-announce-ip
======================
\* cluster-announce-port
========================
\* cluster-announce-tls-port
============================
\* cluster-announce-bus-port
============================
Each instructs the node about its address, client ports (for connections
========================================================================
without and with TLS) and cluster message bus port. The information is then
===========================================================================
published in the header of the bus packets so that other nodes will be able to
==============================================================================
correctly map the address of the node publishing the information.
=================================================================
If cluster-tls is set to yes and cluster-announce-tls-port is omitted or set
============================================================================
to zero, then cluster-announce-port refers to the TLS port. Note also that
==========================================================================
cluster-announce-tls-port has no effect if cluster-tls is set to no.
====================================================================
If the above options are not used, the normal Redis Cluster auto-detection
==========================================================================
will be used instead.
=====================
Note that when remapped, the bus port may not be at the fixed offset of
=======================================================================
clients port + 10000, so you can specify any port and bus-port depending
========================================================================
on how they get remapped. If the bus-port is not set, a fixed offset of
=======================================================================
10000 will be used as usual.
============================
Example:
========
cluster-announce-ip 10.1.1.5
============================
cluster-announce-tls-port 6379
==============================
cluster-announce-port 0
=======================
cluster-announce-bus-port 6380
==============================
################################## SLOW LOG ###################################
The Redis Slow Log is a system to log queries that exceeded a specified
=======================================================================
execution time. The execution time does not include the I/O operations
======================================================================
like talking with the client, sending the reply and so forth,
=============================================================
but just the time needed to actually execute the command (this is the only
==========================================================================
stage of command execution where the thread is blocked and can not serve
========================================================================
other requests in the meantime).
================================
You can configure the slow log with two parameters: one tells Redis
===================================================================
what is the execution time, in microseconds, to exceed in order for the
=======================================================================
command to get logged, and the other parameter is the length of the
===================================================================
slow log. When a new command is logged the oldest one is removed from the
=========================================================================
queue of logged commands.
=========================
The following time is expressed in microseconds, so 1000000 is equivalent
=========================================================================
to one second. Note that a negative number disables the slow log, while
=======================================================================
a value of zero forces the logging of every command.
====================================================
slowlog-log-slower-than 10000
There is no limit to this length. Just be aware that it will consume memory.
============================================================================
You can reclaim memory used by the slow log with SLOWLOG RESET.
===============================================================
slowlog-max-len 128
################################ LATENCY MONITOR ##############################
The Redis latency monitoring subsystem samples different operations
===================================================================
at runtime in order to collect data related to possible sources of
==================================================================
latency of a Redis instance.
============================
Via the LATENCY command this information is available to the user that can
==========================================================================
print graphs and obtain reports.
================================
The system only logs operations that were performed in a time equal or
======================================================================
greater than the amount of milliseconds specified via the
=========================================================
latency-monitor-threshold configuration directive. When its value is set
========================================================================
to zero, the latency monitor is turned off.
===========================================
By default latency monitoring is disabled since it is mostly not needed
=======================================================================
if you don't have latency issues, and collecting data has a performance
=======================================================================
impact, that while very small, can be measured under big load. Latency
======================================================================
monitoring can easily be enabled at runtime using the command
=============================================================
"CONFIG SET latency-monitor-threshold \<milliseconds\>" if needed.
==================================================================
latency-monitor-threshold 0
############################# EVENT NOTIFICATION ##############################
Redis can notify Pub/Sub clients about events happening in the key space.
=========================================================================
This feature is documented at https://redis.io/topics/notifications
===================================================================
For instance if keyspace events notification is enabled, and a client
=====================================================================
performs a DEL operation on key "foo" stored in the Database 0, two
===================================================================
messages will be published via Pub/Sub:
=======================================
PUBLISH **keyspace@0**:foo del
==============================
PUBLISH **keyevent@0**:del foo
==============================
It is possible to select the events that Redis will notify among a set
======================================================================
of classes. Every class is identified by a single character:
============================================================
K Keyspace events, published with **keyspace@\<db\>** prefix.
=============================================================
E Keyevent events, published with **keyevent@\<db\>** prefix.
=============================================================
g Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ...
====================================================================
$ String commands
=================
l List commands
===============
s Set commands
==============
h Hash commands
===============
z Sorted set commands
=====================
x Expired events (events generated every time a key expires)
============================================================
e Evicted events (events generated when a key is evicted for maxmemory)
=======================================================================
t Stream commands
=================
d Module key type events
========================
m Key-miss events (Note: It is not included in the 'A' class)
=============================================================
A Alias for g$lshzxetd, so that the "AKE" string means all the events
=====================================================================
(Except key-miss events which are excluded from 'A' due to their
================================================================
unique nature).
===============
The "notify-keyspace-events" takes as argument a string that is composed
========================================================================
of zero or multiple characters. The empty string means that notifications
=========================================================================
are disabled.
=============
Example: to enable list and generic events, from the point of view of the
=========================================================================
event name, use:
================
notify-keyspace-events Elg
==========================
Example 2: to get the stream of the expired keys subscribing to channel
=======================================================================
name **keyevent@0**:expired use:
================================
notify-keyspace-events Ex
=========================
By default all notifications are disabled because most users don't need
=======================================================================
this feature and the feature has some overhead. Note that if you don't
======================================================================
specify at least one of K or E, no events will be delivered.
============================================================
notify-keyspace-events ""
############################### GOPHER SERVER #################################
Redis contains an implementation of the Gopher protocol, as specified in
========================================================================
the RFC 1436 (https://www.ietf.org/rfc/rfc1436.txt).
====================================================
The Gopher protocol was very popular in the late '90s. It is an alternative
===========================================================================
to the web, and the implementation both server and client side is so simple
===========================================================================
that the Redis server has just 100 lines of code in order to implement this
===========================================================================
support.
========
What do you do with Gopher nowadays? Well Gopher never *really* died, and
=========================================================================
lately there is a movement in order for the Gopher more hierarchical content
============================================================================
composed of just plain text documents to be resurrected. Some want a simpler
============================================================================
internet, others believe that the mainstream internet became too much
=====================================================================
controlled, and it's cool to create an alternative space for people that
========================================================================
want a bit of fresh air.
========================
Anyway for the 10nth birthday of the Redis, we gave it the Gopher protocol
==========================================================================
as a gift.
==========
--- HOW IT WORKS? ---
=====================
The Redis Gopher support uses the inline protocol of Redis, and specifically
============================================================================
two kind of inline requests that were anyway illegal: an empty request
======================================================================
or any request that starts with "/" (there are no Redis commands starting
=========================================================================
with such a slash). Normal RESP2/RESP3 requests are completely out of the
=========================================================================
path of the Gopher protocol implementation and are served as usual as well.
===========================================================================
If you open a connection to Redis when Gopher is enabled and send it
====================================================================
a string like "/foo", if there is a key named "/foo" it is served via the
=========================================================================
Gopher protocol.
================
In order to create a real Gopher "hole" (the name of a Gopher site in Gopher
============================================================================
talking), you likely need a script like the following:
======================================================
https://github.com/antirez/gopher2redis
=======================================
--- SECURITY WARNING ---
========================
If you plan to put Redis on the internet in a publicly accessible address
=========================================================================
to server Gopher pages MAKE SURE TO SET A PASSWORD to the instance.
===================================================================
Once a password is set:
=======================
1. The Gopher server (when enabled, not by default) will still serve
====================================================================
content via Gopher.
===================
2. However other commands cannot be called before the client will
=================================================================
authenticate.
=============
So use the 'requirepass' option to protect your instance.
=========================================================
Note that Gopher is not currently supported when 'io-threads-do-reads'
======================================================================
is enabled.
===========
To enable Gopher support, uncomment the following line and set the option
=========================================================================
from no (the default) to yes.
=============================
gopher-enabled no
=================
############################### ADVANCED CONFIG ###############################
Hashes are encoded using a memory efficient data structure when they have a
===========================================================================
small number of entries, and the biggest entry does not exceed a given
======================================================================
threshold. These thresholds can be configured using the following directives.
=============================================================================
hash-max-ziplist-entries 512
hash-max-ziplist-value 64
Lists are also encoded in a special way to save a lot of space.
===============================================================
The number of entries allowed per internal list node can be specified
=====================================================================
as a fixed maximum size or a maximum number of elements.
========================================================
For a fixed maximum size, use -5 through -1, meaning:
=====================================================
-5: max size: 64 Kb \<-- not recommended for normal workloads
=============================================================
-4: max size: 32 Kb \<-- not recommended
========================================
-3: max size: 16 Kb \<-- probably not recommended
=================================================
-2: max size: 8 Kb \<-- good
============================
-1: max size: 4 Kb \<-- good
============================
Positive numbers mean store up to *exactly* that number of elements
===================================================================
per list node.
==============
The highest performing option is usually -2 (8 Kb size) or -1 (4 Kb size),
==========================================================================
but if your use case is unique, adjust the settings as necessary.
=================================================================
list-max-ziplist-size -2
Lists may also be compressed.
=============================
Compress depth is the number of quicklist ziplist nodes from *each* side of
===========================================================================
the list to *exclude* from compression. The head and tail of the list
=====================================================================
are always uncompressed for fast push/pop operations. Settings are:
===================================================================
0: disable all list compression
===============================
1: depth 1 means "don't start compressing until after 1 node into the list,
===========================================================================
going from either the head or tail"
===================================
So: \[head\]-\>node-\>node-\>...-\>node-\>\[tail\]
==================================================
\[head\], \[tail\] will always be uncompressed; inner nodes will compress.
==========================================================================
2: \[head\]-\>\[next\]-\>node-\>node-\>...-\>node-\>\[prev\]-\>\[tail\]
=======================================================================
2 here means: don't compress head or head-\>next or tail-\>prev or tail,
========================================================================
but compress all nodes between them.
====================================
3: \[head\]-\>\[next\]-\>\[next\]-\>node-\>node-\>...-\>node-\>\[prev\]-\>\[prev\]-\>\[tail\]
=============================================================================================
etc.
====
list-compress-depth 0
Sets have a special encoding in just one case: when a set is composed
=====================================================================
of just strings that happen to be integers in radix 10 in the range
===================================================================
of 64 bit signed integers.
==========================
The following configuration setting sets the limit in the size of the
=====================================================================
set in order to use this special memory saving encoding.
========================================================
set-max-intset-entries 512
Similarly to hashes and lists, sorted sets are also specially encoded in
========================================================================
order to save a lot of space. This encoding is only used when the length and
============================================================================
elements of a sorted set are below the following limits:
========================================================
zset-max-ziplist-entries 128
zset-max-ziplist-value 64
HyperLogLog sparse representation bytes limit. The limit includes the
=====================================================================
16 bytes header. When an HyperLogLog using the sparse representation crosses
============================================================================
this limit, it is converted into the dense representation.
==========================================================
A value greater than 16000 is totally useless, since at that point the
======================================================================
dense representation is more memory efficient.
==============================================
The suggested value is \~ 3000 in order to have the benefits of
===============================================================
the space efficient encoding without slowing down too much PFADD,
=================================================================
which is O(N) with the sparse encoding. The value can be raised to
==================================================================
\~ 10000 when CPU is not a concern, but space is, and the data set is
=====================================================================
composed of many HyperLogLogs with cardinality in the 0 - 15000 range.
======================================================================
hll-sparse-max-bytes 3000
Streams macro node max size / items. The stream data structure is a radix
=========================================================================
tree of big nodes that encode multiple items inside. Using this configuration
=============================================================================
it is possible to configure how big a single node can be in bytes, and the
==========================================================================
maximum number of items it may contain before switching to a new node when
==========================================================================
appending new stream entries. If any of the following settings are set to
=========================================================================
zero, the limit is ignored, so for instance it is possible to set just a
========================================================================
max entries limit by setting max-bytes to 0 and max-entries to the desired
==========================================================================
value.
======
stream-node-max-bytes 4096
stream-node-max-entries 100
Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in
=========================================================================
order to help rehashing the main Redis hash table (the one mapping top-level
============================================================================
keys to values). The hash table implementation Redis uses (see dict.c)
======================================================================
performs a lazy rehashing: the more operation you run into a hash table
=======================================================================
that is rehashing, the more rehashing "steps" are performed, so if the
======================================================================
server is idle the rehashing is never complete and some more memory is used
===========================================================================
by the hash table.
==================
The default is to use this millisecond 10 times every second in order to
========================================================================
actively rehash the main dictionaries, freeing memory when possible.
====================================================================
If unsure:
==========
use "activerehashing no" if you have hard latency requirements and it is
========================================================================
not a good thing in your environment that Redis can reply from time to time
===========================================================================
to queries with 2 milliseconds delay.
=====================================
use "activerehashing yes" if you don't have such hard requirements but
======================================================================
want to free memory asap when possible.
=======================================
activerehashing yes
The client output buffer limits can be used to force disconnection of clients
=============================================================================
that are not reading data from the server fast enough for some reason (a
========================================================================
common reason is that a Pub/Sub client can't consume messages as fast as the
============================================================================
publisher can produce them).
============================
The limit can be set differently for the three different classes of clients:
============================================================================
normal -\> normal clients including MONITOR clients
===================================================
replica -\> replica clients
===========================
pubsub -\> clients subscribed to at least one pubsub channel or pattern
=======================================================================
The syntax of every client-output-buffer-limit directive is the following:
==========================================================================
client-output-buffer-limit \<class\> \<hard limit\> \<soft limit\> \<soft seconds\>
===================================================================================
A client is immediately disconnected once the hard limit is reached, or if
==========================================================================
the soft limit is reached and remains reached for the specified number of
=========================================================================
seconds (continuously).
=======================
So for instance if the hard limit is 32 megabytes and the soft limit is
=======================================================================
16 megabytes / 10 seconds, the client will get disconnected immediately
=======================================================================
if the size of the output buffers reach 32 megabytes, but will also get
=======================================================================
disconnected if the client reaches 16 megabytes and continuously overcomes
==========================================================================
the limit for 10 seconds.
=========================
By default normal clients are not limited because they don't receive data
=========================================================================
without asking (in a push way), but just after a request, so only
=================================================================
asynchronous clients may create a scenario where data is requested faster
=========================================================================
than it can read.
=================
Instead there is a default limit for pubsub and replica clients, since
======================================================================
subscribers and replicas receive data in a push fashion.
========================================================
Both the hard or the soft limit can be disabled by setting them to zero.
========================================================================
client-output-buffer-limit normal 0 0 0
client-output-buffer-limit replica 256mb 64mb 60
client-output-buffer-limit pubsub 32mb 8mb 60
Client query buffers accumulate new commands. They are limited to a fixed
=========================================================================
amount by default in order to avoid that a protocol desynchronization (for
==========================================================================
instance due to a bug in the client) will lead to unbound memory usage in
=========================================================================
the query buffer. However you can configure it here if you have very special
============================================================================
needs, such us huge multi/exec requests or alike.
=================================================
client-query-buffer-limit 1gb
=============================
In the Redis protocol, bulk requests, that are, elements representing single
============================================================================
strings, are normally limited to 512 mb. However you can change this limit
==========================================================================
here, but must be 1mb or greater
================================
proto-max-bulk-len 512mb
========================
Redis calls an internal function to perform many background tasks, like
=======================================================================
closing connections of clients in timeout, purging expired keys that are
========================================================================
never requested, and so forth.
==============================
Not all tasks are performed with the same frequency, but Redis checks for
=========================================================================
tasks to perform according to the specified "hz" value.
=======================================================
By default "hz" is set to 10. Raising the value will use more CPU when
======================================================================
Redis is idle, but at the same time will make Redis more responsive when
========================================================================
there are many keys expiring at the same time, and timeouts may be
==================================================================
handled with more precision.
============================
The range is between 1 and 500, however a value over 100 is usually not
=======================================================================
a good idea. Most users should use the default of 10 and raise this up to
=========================================================================
100 only in environments where very low latency is required.
============================================================
hz 10
Normally it is useful to have an HZ value which is proportional to the
======================================================================
number of clients connected. This is useful in order, for instance, to
======================================================================
avoid too many clients are processed for each background task invocation
========================================================================
in order to avoid latency spikes.
=================================
Since the default HZ value by default is conservatively set to 10, Redis
========================================================================
offers, and enables by default, the ability to use an adaptive HZ value
=======================================================================
which will temporarily raise when there are many connected clients.
===================================================================
When dynamic HZ is enabled, the actual configured HZ will be used
=================================================================
as a baseline, but multiples of the configured HZ value will be actually
========================================================================
used as needed once more clients are connected. In this way an idle
===================================================================
instance will use very little CPU time while a busy instance will be
====================================================================
more responsive.
================
dynamic-hz yes
When a child rewrites the AOF file, if the following option is enabled
======================================================================
the file will be fsync-ed every 32 MB of data generated. This is useful
=======================================================================
in order to commit the file to the disk more incrementally and avoid
====================================================================
big latency spikes.
===================
aof-rewrite-incremental-fsync yes
When redis saves RDB file, if the following option is enabled
=============================================================
the file will be fsync-ed every 32 MB of data generated. This is useful
=======================================================================
in order to commit the file to the disk more incrementally and avoid
====================================================================
big latency spikes.
===================
rdb-save-incremental-fsync yes
Redis LFU eviction (see maxmemory setting) can be tuned. However it is a good
=============================================================================
idea to start with the default settings and only change them after investigating
================================================================================
how to improve the performances and how the keys LFU change over time, which
============================================================================
is possible to inspect via the OBJECT FREQ command.
===================================================
There are two tunable parameters in the Redis LFU implementation: the
=====================================================================
counter logarithm factor and the counter decay time. It is important to
=======================================================================
understand what the two parameters mean before changing them.
=============================================================
The LFU counter is just 8 bits per key, it's maximum value is 255, so Redis
===========================================================================
uses a probabilistic increment with logarithmic behavior. Given the value
=========================================================================
of the old counter, when a key is accessed, the counter is incremented in
=========================================================================
this way:
=========
1. A random number R between 0 and 1 is extracted.
==================================================
2. A probability P is calculated as 1/(old_value\*lfu_log_factor+1).
====================================================================
3. The counter is incremented only if R \< P.
=============================================
The default lfu-log-factor is 10. This is a table of how the frequency
======================================================================
counter changes with a different number of accesses with different
==================================================================
logarithmic factors:
====================
+--------+------------+------------+------------+------------+------------+
===========================================================================
\| factor \| 100 hits \| 1000 hits \| 100K hits \| 1M hits \| 10M hits \|
=========================================================================
+--------+------------+------------+------------+------------+------------+
===========================================================================
\| 0 \| 104 \| 255 \| 255 \| 255 \| 255 \|
==========================================
+--------+------------+------------+------------+------------+------------+
===========================================================================
\| 1 \| 18 \| 49 \| 255 \| 255 \| 255 \|
========================================
+--------+------------+------------+------------+------------+------------+
===========================================================================
\| 10 \| 10 \| 18 \| 142 \| 255 \| 255 \|
=========================================
+--------+------------+------------+------------+------------+------------+
===========================================================================
\| 100 \| 8 \| 11 \| 49 \| 143 \| 255 \|
========================================
+--------+------------+------------+------------+------------+------------+
===========================================================================
NOTE: The above table was obtained by running the following commands:
=====================================================================
redis-benchmark -n 1000000 incr foo
===================================
redis-cli object freq foo
=========================
NOTE 2: The counter initial value is 5 in order to give new objects a chance
============================================================================
to accumulate hits.
===================
The counter decay time is the time, in minutes, that must elapse in order
=========================================================================
for the key counter to be divided by two (or decremented if it has a value
==========================================================================
less \<= 10).
=============
The default value for the lfu-decay-time is 1. A special value of 0 means to
============================================================================
decay the counter every time it happens to be scanned.
======================================================
lfu-log-factor 10
=================
lfu-decay-time 1
================
########################### ACTIVE DEFRAGMENTATION #######################
What is active defragmentation?
===============================
-------------------------------
===============================
Active (online) defragmentation allows a Redis server to compact the
====================================================================
spaces left between small allocations and deallocations of data in memory,
==========================================================================
thus allowing to reclaim back memory.
=====================================
Fragmentation is a natural process that happens with every allocator (but
=========================================================================
less so with Jemalloc, fortunately) and certain workloads. Normally a server
============================================================================
restart is needed in order to lower the fragmentation, or at least to flush
===========================================================================
away all the data and create it again. However thanks to this feature
=====================================================================
implemented by Oran Agra for Redis 4.0 this process can happen at runtime
=========================================================================
in a "hot" way, while the server is running.
============================================
Basically when the fragmentation is over a certain level (see the
=================================================================
configuration options below) Redis will start to create new copies of the
=========================================================================
values in contiguous memory regions by exploiting certain specific Jemalloc
===========================================================================
features (in order to understand if an allocation is causing fragmentation
==========================================================================
and to allocate it in a better place), and at the same time, will release the
=============================================================================
old copies of the data. This process, repeated incrementally for all the keys
=============================================================================
will cause the fragmentation to drop back to normal values.
===========================================================
Important things to understand:
===============================
1. This feature is disabled by default, and only works if you compiled Redis
============================================================================
to use the copy of Jemalloc we ship with the source code of Redis.
==================================================================
This is the default with Linux builds.
======================================
2. You never need to enable this feature if you don't have fragmentation
========================================================================
issues.
=======
3. Once you experience fragmentation, you can enable this feature when
======================================================================
needed with the command "CONFIG SET activedefrag yes".
======================================================
The configuration parameters are able to fine tune the behavior of the
======================================================================
defragmentation process. If you are not sure about what they mean it is
=======================================================================
a good idea to leave the defaults untouched.
============================================
Enabled active defragmentation
==============================
activedefrag no
===============
Minimum amount of fragmentation waste to start active defrag
============================================================
active-defrag-ignore-bytes 100mb
================================
Minimum percentage of fragmentation to start active defrag
==========================================================
active-defrag-threshold-lower 10
================================
Maximum percentage of fragmentation at which we use maximum effort
==================================================================
active-defrag-threshold-upper 100
=================================
Minimal effort for defrag in CPU percentage, to be used when the lower
======================================================================
threshold is reached
====================
active-defrag-cycle-min 1
=========================
Maximal effort for defrag in CPU percentage, to be used when the upper
======================================================================
threshold is reached
====================
active-defrag-cycle-max 25
==========================
Maximum number of set/hash/zset/list fields that will be processed from
=======================================================================
the main dictionary scan
========================
active-defrag-max-scan-fields 1000
==================================
Jemalloc background thread for purging will be enabled by default
=================================================================
jemalloc-bg-thread yes
It is possible to pin different threads and processes of Redis to specific
==========================================================================
CPUs in your system, in order to maximize the performances of the server.
=========================================================================
This is useful both in order to pin different Redis threads in different
========================================================================
CPUs, but also in order to make sure that multiple Redis instances running
==========================================================================
in the same host will be pinned to different CPUs.
==================================================
Normally you can do this using the "taskset" command, however it is also
========================================================================
possible to this via Redis configuration directly, both in Linux and FreeBSD.
=============================================================================
You can pin the server/IO threads, bio threads, aof rewrite child process, and
==============================================================================
the bgsave child process. The syntax to specify the cpu list is the same as
===========================================================================
the taskset command:
====================
Set redis server/io threads to cpu affinity 0,2,4,6:
====================================================
server_cpulist 0-7:2
====================
Set bio threads to cpu affinity 1,3:
====================================
bio_cpulist 1,3
===============
Set aof rewrite child process to cpu affinity 8,9,10,11:
========================================================
aof_rewrite_cpulist 8-11
========================
Set bgsave child process to cpu affinity 1,10,11
================================================
bgsave_cpulist 1,10-11
======================
In some cases redis will emit warnings and even refuse to start if it detects
=============================================================================
that the system is in bad state, it is possible to suppress these warnings
==========================================================================
by setting the following config which takes a space delimited list of warnings
==============================================================================
to suppress
===========
ignore-warnings ARM64-COW-BUG
=============================
5、启动Redis容器 {#5启动redis容器}
执行命令启动redis容器：
docker-compose up -d
6、远程连接验证结果 {#6远程连接验证结果}
信息填完，点击OK
点击左侧对呀的连接，右侧出现redis服务器信息则为安装成功
