Nginx+Tomcat+Keepalived实现高可用web集群：

环境：CenOS 6.5
Nginx-Master：10.10.10.128
Nginx-Backup：10.10.10.129
Tomcat1：10.10.10.130
Tomcat2：10.10.10.131
VIP：10.10.10.100

一、环境基础配置

1、更换国内yum源

2、关闭防火墙、SELinux

3、时间同步

二、Web端安装Web服务

1、查看是否安装JDK
[root@Tomcat1 ~]# java -version
java version "1.8.0_171"
Java(TM) SE Runtime Environment (build 1.8.0_171-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.171-b11, mixed mode)
2、安装JDK
官网下载二进制包
解压到/usr/local/java
    tar zxvf jdk-8u171-linux-x64.tar.gz -C /usr/local/java/
修改环境变量/etc/profile
    JAVA_HOME=/usr/local/java
    PATH=$JAVA_HOME/bin:$PATH
    CLASSPATH=$JAVA_HOME/jre/lib/ext:$JAVA_HOME/lib/tools.jar
    export PATH JAVA_HOME CLASSPATH
使环境变量生效：
    source /etc/profile
3、下载Tomcat源码包：
    wget -O /opt/apache-tomcat-9.0.7.tar.gz http://mirrors.hust.edu.cn/apache/tomcat/tomcat-9/v9.0.7/bin/apache-tomcat-9.0.7.tar.gz
4、解压到/usr/local/tomcat
    tar zxvf /opt/apache-tomcat-9.0.7.tar.gz -C /usr/local/
5、修改Tomcat的主页
    rm -rf /usr/local/apache-tomcat-9.0.7/webapps/ROOT/*
    echo "Tomcat1" >/usr/local/apache-tomcat-9.0.7/webapps/ROOT/index.html  #Tomcat1
    echo "Tomcat2" >/usr/local/apache-tomcat-9.0.7/webapps/ROOT/index.html  #Tomcat2
6、测试Tomcat能否正常启动
[root@Tomcat1 bin]# ./usr/local/apache-tomcat-9.0.7/bin
/startup.sh 
Using CATALINA_BASE:   /usr/local/apache-tomcat-9.0.7
Using CATALINA_HOME:   /usr/local/apache-tomcat-9.0.7
Using CATALINA_TMPDIR: /usr/local/apache-tomcat-9.0.7/temp
Using JRE_HOME:        /usr/local/java
Using CLASSPATH:       /usr/local/apache-tomcat-9.0.7/bin/bootstrap.jar:/usr/local/apache-tomcat-9.0.7/bin/tomcat-juli.jar
Tomcat started.
curl 10.10.10.130:8080   #返回Tomcat1
curl 10.10.10.131:8080   #返回Tomcat2
至此web端配置完成。

二、Nginx反向代理安装

1、安装依赖软件
    yum install -y gcc gcc-c++
    yum install -y pcre pcre-devel openssl openssl-devel zlib zlib-devel
2、官网下载源码包
3、解压源码包
    tar zxvf nginx-1.14.0.tar.gz -C /tmp/
4、编译安装
    useradd -s /bin/false -M nginx
    ./configure --user=nginx --group=nginx --prefix=/usr/local/nginx-1.14.0/ --with-http_v2_module --with-http_ssl_module --with-http_sub_module --with-http_stub_status_module --with-http_gzip_static_module --with-pcre
    make && make install
5、配置反向代理/usr/local/nginx/conf/nginx.conf
worker_processes  1;
pid        /usr/local/nginx/logs/nginx.pid;
worker_rlimit_nofile 51200;
events {
   use epoll;
   worker_connections  51200;
}
http {
   include       mime.types;
   default_type  application/octet-stream;
   server_names_hash_bucket_size 128;
   client_header_buffer_size 32k;
   large_client_header_buffers 4 32k;
   client_max_body_size 8m;
   sendfile        on;
   tcp_nopush      on;
   keepalive_timeout  65;
   tcp_nodelay on;
   gzip on;
   gzip_min_length 1k;
   gzip_buffers 4 16k;
   gzip_http_version 1.0;
   gzip_comp_level 2;
   gzip_types    test/plain application/x-javascript test/css application/xml;
   gzip_vary on; 
upstream backend {
server 10.10.10.130:8080;
server 10.10.10.131:8080;
}
server {
listen       80;
server_name  10.10.10.128;   #Nginx2改为：10.10.10.129
location / {
root   /var/www/html;
index  index.php index.html index.htm;
proxy_pass http://backend;
}
}
}
先测试再启动：
[root@Nginx1 ~]# /usr/local/nginx-1.14.0/sbin/nginx -t
nginx: the configuration file /usr/local/nginx-1.14.0//conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx-1.14.0//conf/nginx.conf test is successful
[root@Nginx1 ~]# /usr/local/nginx-1.14.0/sbin/nginx
[root@Nginx1 ~]# lsof -i:80
COMMAND  PID  USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
nginx   4896  root    6u  IPv4  18439      0t0  TCP *:http (LISTEN)
nginx   4897 nginx    6u  IPv4  18439      0t0  TCP *:http (LISTEN)
curl 10.10.10.128  #轮询返回Tomcat1 Tomcat2
Nginx2同样的搭建。
至此Nginx反向代理搭建完成。

三、使用Keepalived实现高可用

1、安装：
    yum install keepalived -y
2、修改配置文件/etc/keepalived/keepalived.conf
MASTER 端：
! Configuration File for keepalived
vrrp_script check_nginx {
        script "/etc/keepalived/check_nginx.sh"
        interval 2
        weight 2
}
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL1
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.10.10.100/24 dev eth0
}
track_script {
check_nginx
}
}
BACKUP端：
修改：
router_id LVS_DEVEL2
state BACKUP
priority 90
检测Nginx脚本：
#!/bin/bash
nginxpid=`ps -C nginx --no-header | wc -l`
if [ $nginxpid -eq 0 ];then
/etc/init.d/keepalived stop
fi
chmod +x /etc/keepalived/check_nginx.sh
重启Keepalived服务
service keepalived restart

四、检验服务的高可用

Nginx1执行：killall nginx
发现 web访问依然正常
Tomcat1执行：/usr/local/apache-tomcat-9.0.7/bin/shutdown.sh
发现 web访问依然正常
高可用的环境搭建完毕。