keepalived检测脚本及注意事项

keepalived检测脚本的作用及注意事项：

1. 默认每隔3秒钟执行一次检测脚本，检查nginx服务是否启动，如果没启动就把nginx服务启动起来，如果启动不成功，就把keepalived服务down掉，让漂浮到备keepalived上

2. 检测脚本
   #!/bin/bash
   run=`ps -C nginx --no-header | wc -l`
   if [ $run -eq 0 ]
   then
   /usr/local/nginx/sbin/nginx -s stop
   /usr/local/nginx/sbin/nginx
   sleep 3
   if [ `ps -C nginx --no-header | wc -l` ]
   then
   killall keepalived
   fi
   fi

3. 检测脚本一定要写在vrrp_instance的前面也就是上面，而且花括号一定要有空格，追踪trace_script要定在vip的后面，多少人栽在了这上面好多小时

4. vrrp_script check_ng {
   script " /etc/keepalived/check_nginx.sh "
   interval 2
   }
   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 {
   192.168.76.25/24
   }
   track_script {
   check_ng
   }
   }