nginx+keepalived实现高可用集群搭建

通过keepalived搭建ningx集群，实现nginx高可用。

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流程

keepalived作用

Keepalived是一个基于VRRP协议来实现的服务高可用方案，可以利用其来避免IP单点故障，
对外虚拟一个vip ip节点。vrrp协议可以百度到

nginx+keepalived搭建

• 准备工作
  • linux虚拟机2台。master ip=192.168.112.97 slave ip=192.168.112.98 虚拟VIP ip=192.168.112.50
  • 在两台服务器上面都安装nginx和keepalived
  • 在slave节点绑定 虚拟静态ip ifconfig eth0:1 192.168.112.50 netmask 255.255.255.0 up

• keepalived安装过程

  • 安装命令：apt-get install keepalived
  • 启动和停止命令：service keepalived start、 service keepalived stop
  • keepalived 默认读取/etc/keepalived/keepalived.conf 下面的配置文件，我们可以cat /var/log/syslog 查看keepalived的启动日志

  • /etc/keepalived/keepalived.conf 配置文件：

    vi  keepalived.conf
       global_defs {
           notification_email {
               zhouxiao@example.com
               itsection@example.com
           }
           notification_email_from itsection@example.com
           smtp_server mail.example.com
           smtp_connect_timeout 30
           router_id LVS_DEVEL
       }
    
       vrrp_script chk_nginx {
           script "/etc/keepalived/check_nginx.sh" 
           interval 2 
           weight -5 
           fall 3  
           rise 2 
       }
    
       vrrp_instance VI_1 {
        #节点状态
           state MASTER
        # 网卡
           interface eth0
        # 当前ip
           mcast_src_ip 192.168.112.97
        # 虚拟节点id 必须一样
           virtual_router_id 51
        #优先级
           priority 101
           advert_int 2
           authentication {
               auth_type PASS
               auth_pass 1111
           }
        #虚拟节点ip
           virtual_ipaddress {
               192.168.112.50
           }
        # 监控脚本
           track_script {
              chk_nginx 
           }
       }
    

  • /etc/keepalived/check_nginx.sh

    vi check_nginx.sh
    #!/bin/bash
    #这种方式会把ps的信息打印出来，显示的不准确
    #num=`ps -ef|grep nginx|wc -l`
    num=$(ps -C nginx --no-heading|wc -l)
    if [ $num -le 0 ]
      then
            #启动ngingx
            /usr/local/nginx/sbin/nginx
            #休眠2秒
            sleep 2
            num=$(ps -C nginx --no-heading|wc -l)
      if [ $num -le 0 ];then
            service keepalived stop
            cd /etc/keepalived/
            echo "no nginx start">>gao.txt
       fi
    fi
    

    • 相关解释：
      check_nginx.sh是用来检测 nginx是否正常运行的脚本，keepalived可以动态根据检测执行这个脚本 决定那台服务器的keepalived是vip节点。
      master 的配置文件和 slave的keepalived.conf 文件区别在于 state MASTER -> state BACKUP，priority 101 -> priority 100，mcast_src_ip 192.168.112.97 -> mcast_src_ip 192.168.112.98即可

测试

启动nginx和keepalived，访问VIP ip 192.168.112.50  显示的是master的nginx内容。

stop master的keepalive的  再访问vip节点  显示的是slave的内容

参考网址

https://segmentfault.com/a/1190000002881132