CentOS7 下面通过keepalived 配置nginx 主从方式的双机热备

这里我们采用两台Nginx服务器作为前端，一主一从，Keepalived实现状态监测，保证Nginx正常对外提供服务，即主Nginx服务进程死掉之后，keepalived能够通过其自身的检测机制将网站的访问切换到从Nginx上来。
主服务器IP：192.168.1.217
从服务IP：192.168.1.218
虚IP：192.168.1.219
你可以将你网站域名解析到 192.168.1.219 对应的公网IP上，这样主从服务器可以轮流接管该虚IP，保证网站正常对外提供访问

- 安装nginx

• 通过yum 安装nginx
• 详情查看上篇博文

- 安装keepalived

• yum install keepalived

- 配置keepalived

• 配置nginx-001服务器

  
  #先备份配置文件
  
  cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
  vim /etc/keepalived/keepalived.conf
  
  #修改成如下内容
  
  ! Configuration File for keepalived
  global_defs {
      router_id nginx_server_1
  }
  vrrp_script chk_nginx {
      script "/etc/keepalived/nginx_check.sh"
      interval 2
      weight 20
      !weight为正数
      !如果脚本执行结果为0,,Master:weight+priority>Backup:weight+priority(不切换)
      !如果脚本执行结果不为0,Master:priority:priority+weight(切换)
      !weight为负数
      !如果脚本执行结果为0,,Master:priority>Backup:priority(不切换)
      !如果脚本执行结果不为0,Master:priority+weight:priority(切换)
      !一般来说,weight的绝对值要大于Master和Backup的priority之差
  }
  vrrp_instance VI_1 {
      state MASTER
      interface eno16777984
      virtual_router_id 51
      mcast_src_ip 192.168.1.217
      priority 100
      nopreempt
      advert_int 1
      authentication {
          auth_type PASS
          auth_pass 1111
      }
      track_script {
          chk_nginx
      }
      virtual_ipaddress {
          192.168.1.219/24
      }
  }
  
  
  #检查nginx进程的代码,当nginx进程奔溃后，keepalived自动启动nginx
  
  vim /etc/keepalived/nginx_check.sh
  
  #添加如下代码
  
  
  #!/bin/bash
  
  A=`ps -C nginx --no-header |wc -l`
  if [ $A -eq 0 ];then
      /usr/sbin/nginx
      sleep 2
      if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
          killall keepalived
      fi
  fi
  
  
  #改成可执行文件
  
  chmod +xxx /etc/keepalived/nginx_check.sh

  • 配置nginx-002服务器（从）

  
  #先备份配置文件
  
  cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
  vim /etc/keepalived/keepalived.conf
  
  #修改成如下内容
  
  （注意:
      state 和主不一样，是BACKUP
      route_id 和主不一样
      priority 小于主机
  )
  
  ! Configuration File for keepalived
  global_defs {
      router_id nginx_server_2
  }
  vrrp_script chk_nginx {
      script "/etc/keepalived/nginx_check.sh"
      interval 2
      weight 20
      !weight为正数
      !如果脚本执行结果为0,,Master:weight+priority>Backup:weight+priority(不切换)
      !如果脚本执行结果不为0,Master:priority:priority+weight(切换)
      !weight为负数
      !如果脚本执行结果为0,,Master:priority>Backup:priority(不切换)
      !如果脚本执行结果不为0,Master:priority+weight:priority(切换)
      !一般来说,weight的绝对值要大于Master和Backup的priority之差
  }
  vrrp_instance VI_1 {
      state BACKUP
      interface eno16777984
      virtual_router_id 51
      mcast_src_ip 192.168.1.218
      priority 90
      nopreempt
      advert_int 1
      authentication {
          auth_type PASS
          auth_pass 1111
      }
      track_script {
          chk_nginx
      }
      virtual_ipaddress {
          192.168.1.219/24
      }
  }

- 启动keepalived

systemctl start keepalived
systemctl enable keepalived

- 测试keepalived+nginx的主从

• 在主机上 ip a ，查看192.168.1.219成功绑定。
• shutdown主机，查看从机192.168.1.219成功绑定。说明vip成功漂移