keepalived（3）- keepalived+nginx实现WEB负载均衡高可用集群

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目录

• 1. keepalived+nginx实现WEB负载均衡高可用集群
  • 1.1 需求和环境描述
  • 1.2 WEB集群部署
  • 1.3 负载均衡集群部署
  • 1.4 keepalived部署
  • 1.5 测试监控的接口down后keepalived的情况
  • 1.6 测试nginx服务异常时keepalived的情况
  • 1.7 测试chk_down脚本生效后keepalived的情况

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1. keepalived+nginx实现WEB负载均衡高可用集群

nginx作为负载均衡设备可以将流量调度到后端WEB集群中，但是nginx本身没有做到高可用，需要结合keepalived技术解决nginx的单点故障问题，因此通常需要nginx结合keepalived技术实现架构的高可用。

1.1 需求和环境描述

高可用nginx设计需求：

• 使用nginx+keepalived模型时需要监控nginx的状态，当nginx服务异常时，需要降低keepalived的优先级，进行VIP切换，此功能可以通过keepalived的track_script脚本功能实现，后端RS健康状态监测可以由nginx实现。

• 同时keepalived状态切换时也需要保证nginx进程启动，可以在keepalived状态切换为BACKUP或MASTER时通过notify.sh脚本再次启动一次nginx服务。

环境说明如下：

• 客户端：地址：192.168.20.1
• 负载均衡集群
  • 节点1：主机名：nginx-lb01，地址：eth1:192.168.20.19（外部），eth2：192.168.50.19（内部）
  • 节点2：主机名：nginx-lb02，地址：eth1:192.168.20.20（外部），eth2：192.168.50.20（内部）
  • 负载均衡集群对外提供两个虚地址：192.168.20.28和192.168.20.29，其中192.168.20.28的MASTER节点为nginx-lb01，192.168.20.29的MASTER节点为nginx-lb02，前端可以通过DNS轮询把用户请求调度到不同的负载均衡节点上，实现分流互备。
• WEB集群
  • 节点1：主机名：nginx02，地址：192.168.50.22
  • 节点2：主机名：nginx03，地址：192.168.50.23

1.2 WEB集群部署

• nginx02节点部署

  #1.nginx的配置文件如下：
  [root@nginx02 ~]# cat /etc/nginx/conf.d/xuzhichao.conf 
  server {
  	listen 80 default_server;
  	server_name www.xuzhichao.com;
  	access_log /var/log/nginx/access_xuzhichao.log access_json;
  	charset utf-8,gbk;	
  	keepalive_timeout 65;
  	
  	#防盗链
  	valid_referers none blocked server_names *.b.com  b.*  ~\.baidu\.  ~\.google\.;
  	
  	if ( $invalid_referer ) {
  		return 403;	
  	}
      
  	#浏览器图标
  	location = /favicon.ico {
  		root /data/nginx/xuzhichao;
  	}
  
  	location / {
  		root /data/nginx/xuzhichao;
  		index index.html index.php;
  	}
  
  	location ~ \.php$ {
  		root /data/nginx/xuzhichao;
  
  		#fastcgi反向代理
  		fastcgi_pass 127.0.0.1:9000;
  		fastcgi_index index.php;
  		fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
  		fastcgi_param HTTPS on;
  		fastcgi_hide_header X-Powered-By;
  		include fastcgi_params;
  	}
  
  	location = /nginx_status {
  		access_log off;
  		allow 192.168.20.0/24;
  		deny all;
  		stub_status;
  	}
  }
  
  #2.nginx工作目录：
  [root@nginx02 ~]# ll /data/nginx/xuzhichao/index.html 
  -rw-r--r-- 1 nginx nginx 25 Jun 28 00:04 /data/nginx/xuzhichao/index.html
  [root@nginx02 ~]# cat /data/nginx/xuzhichao/index.html
  node1.xuzhichao.com page
  
  #3.启动nginx服务：
  [root@nginx02 ~]# nginx -t
  nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
  nginx: configuration file /etc/nginx/nginx.conf test is successful
  [root@nginx02 ~]# systemctl start nginx.service
  
  #4.负载均衡测试访问情况：
  [root@nginx-lb02 ~]# curl -Hhost:www.xuzhichao.com 192.168.50.22
  node1.xuzhichao.com page
  

• nginx03节点部署

  #1.nginx的配置文件如下：
  [root@nginx03 ~]# cat /etc/nginx/conf.d/xuzhichao.conf 
  server {
  	listen 80 default_server;
  	server_name www.xuzhichao.com;
  	access_log /var/log/nginx/access_xuzhichao.log access_json;
  	charset utf-8,gbk;	
  	keepalive_timeout 65;
  	
  	#防盗链
  	valid_referers none blocked server_names *.b.com  b.*  ~\.baidu\.  ~\.google\.;
  	
  	if ( $invalid_referer ) {
  		return 403;	
  	}
      
  	#浏览器图标
  	location = /favicon.ico {
  		root /data/nginx/xuzhichao;
  	}
  
  	location / {
  		root /data/nginx/xuzhichao;
  		index index.html index.php;
  	}
  
  	location ~ \.php$ {
  		root /data/nginx/xuzhichao;
  
  		#fastcgi反向代理
  		fastcgi_pass 127.0.0.1:9000;
  		fastcgi_index index.php;
  		fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
  		fastcgi_param HTTPS on;
  		fastcgi_hide_header X-Powered-By;
  		include fastcgi_params;
  	}
  
  	location = /nginx_status {
  		access_log off;
  		allow 192.168.20.0/24;
  		deny all;
  		stub_status;
  	}
  }
  
  #2.nginx工作目录：
  [root@nginx03 ~]# ll /data/nginx/xuzhichao/index.html 
  -rw-r--r-- 1 nginx nginx 25 Jun 28 00:04 /data/nginx/xuzhichao/index.html
  [root@nginx03 ~]# cat /data/nginx/xuzhichao/index.html
  node2.xuzhichao.com page
  
  #3.启动nginx服务：
  [root@nginx03 ~]# nginx -t
  nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
  nginx: configuration file /etc/nginx/nginx.conf test is successful
  [root@nginx03 ~]# systemctl start nginx.service
  
  #4.负载均衡测试访问情况：
  [root@nginx-lb03 ~]# curl -Hhost:www.xuzhichao.com 192.168.50.23
  node2.xuzhichao.com page
  

1.3 负载均衡集群部署

• nginx-lb01和nginx-lb02配置文件完全一致：

  #1.nginx的配置文件如下：
  [root@nginx-lb01 certs]# cat /etc/nginx/conf.d/xuzhichao.conf 
  upstream webserver {
  	server 192.168.50.22 fail_timeout=5s max_fails=3;
  	server 192.168.50.23 fail_timeout=5s max_fails=3;
      keepalive 32;
  }
  
  server {
  	listen 443 ssl;
  	listen 80;
  	server_name www.xuzhichao.com;
  	access_log /var/log/nginx/access_xuzhichao.log access_json;
  
  	ssl_certificate /etc/nginx/certs/xuzhichao.crt;
  	ssl_certificate_key /etc/nginx/certs/xuzhichao.key;
  	ssl_session_cache shared:ssl_cache:30m;
  	ssl_session_timeout 10m;
  
  	valid_referers none blocked server_names *.b.com  b.*  ~\.baidu\.  ~\.google\.;
  
  	if ( $invalid_referer ) {
  		return 403;	
  	}
  	
      location / {
  		
  		if ( $scheme = http ) {
  			rewrite /(.*) https://www.xuzhichao.com/$1 permanent;
  		}
  
  		proxy_pass http://webserver;
  		include proxy_params;
  	}
  }
  
  [root@nginx-lb01 certs]# cat /etc/nginx/proxy_params 
  proxy_set_header host $http_host;
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  
  proxy_connect_timeout 30;
  proxy_send_timeout 60;
  proxy_read_timeout 60;										        
  
  proxy_buffering on;
  proxy_buffer_size 64k;
  proxy_buffers 4 64k;
  
  #2.启动nginx
  [root@nginx-lb01 certs]# systemctl start nginx.service
  
  #3.客户端通过分别测试两台负载均衡设备
  #测试nginx-lb01负载均衡
  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.19 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  
  #测试nginx-lb02负载均衡
  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.20 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  

1.4 keepalived部署

• nginx-lb01节点的keepalived部署如下：

  #1.keepalived配置文件：
  [root@nginx-lb01 keepalived]# cat /etc/keepalived/keepalived.conf
  ! Configuration File for keepalived
  
  global_defs {
     notification_email {
       root@localhost
     }
     notification_email_from keepalived@localhost
     smtp_server 127.0.0.1
     smtp_connect_timeout 30
     router_id keepalived01
     script_user root
     enable_script_security
     vrrp_mcast_group4 224.0.0.19
  }
  
  vrrp_script chk_down {
  	script "/etc/keepalived/chk_down.sh"    <==检测脚本，可以直接写命令，也可以调用脚本，脚本需要有执行权限，此处表示若/etc/keepalived/down文件存在，则vrrp优先级减少50
  	weight -50   <==如果脚本退出状态为1，则触发优先级减少50
  	interval 1   <==脚本检测的周期，1s检测一次
  	fall 3       <==脚本检测3次都失败则认为检测失败，触发优先级减少50
  	rise 3       <==脚本检测3此都成功则认为检测成功，优先级恢复
  }
  
  #注意：在检测脚本中减少weight值是不生效的，如果在vrrp_script字段中没有设置weight值，则脚本状态值为1则直接把keepalived状态置为fault状态。
  vrrp_script chk_nginx {
  	script "/etc/keepalived/chk_nginx.sh"   <==调用检测脚本，脚本需要有执行权限
  	interval 5    <==注意：每5秒执行一次脚本, 脚本执行过程不能超过5秒,否则会被中断再次重新运行脚本。
  }
  
  vrrp_instance VI_1 {
      state MASTER
      interface eth1
      virtual_router_id 51
      priority 120
      advert_int 3
      authentication {
          auth_type PASS
          auth_pass 1111
      }
      virtual_ipaddress {
          192.168.20.28/24 dev eth1
      }
  
      track_interface {
      	eth2
  	eth0
      }
  
      track_script {
      	chk_down
  	chk_nginx
      }
  
      notify_master "/etc/keepalived/notify.sh master"
      notify_backup "/etc/keepalived/notify.sh backup"
      notify_fault "/etc/keepalived/notify.sh fault"
  }
  
  vrrp_instance VI_2 {
      state BACKUP
      interface eth1
      virtual_router_id 52
      priority 100
      advert_int 3
      authentication {
          auth_type PASS
          auth_pass 2222
      }
      
      virtual_ipaddress {
          192.168.20.29/24 dev eth1
      }
      
      track_interface {
      	eth2
  	eth0
      }
  
      track_script {
      	chk_down
  	chk_nginx
      }
  
      notify_master "/etc/keepalived/notify.sh master"
      notify_backup "/etc/keepalived/notify.sh backup"
      notify_fault "/etc/keepalived/notify.sh fault"
  }
  
  
  #2.chk_nginx脚本文件：
  [root@nginx-lb01 keepalived]# cat /etc/keepalived/chk_nginx.sh 
  #!/bin/bash
  
  nginxpid=$(pidof nginx | wc -l) 
  
  #1.判断Nginx是否存活,如果不存活则尝试启动Nginx
  if [ $nginxpid -eq 0 ];then 
  	systemctl start nginx 
  	sleep 2 
  	
  	#2.等待2秒后再次获取一次Nginx状态 
  	nginxpid=$(pidof nginx | wc -l) 
  	
  	#3.再次进行判断, 如Nginx还不存活则停止Keepalived,让虚地址进行漂移,并退出脚本 
  	if [ $nginxpid -eq 0 ];then 
  		systemctl stop keepalived
  	fi
  fi
  
  #3.notify.sh文件：
  [root@nginx-lb01 keepalived]# cat /etc/keepalived/notify.sh 
  #!/bin/bash
  
  contact='root@localhost'
  notify() {
  	local mailsubject="$(hostname) to be $1, vip floating"
  	local mailbody="$(date +'%F %T'): vrrp transition, $(hostname) changed to be $1"
  	echo "$mailbody" | mail -s "$mailsubject" $contact
  }
  
  case $1 in
  master)
      notify master
  	systemctl start nginx   <==keepalived状态切换时触发启动nginx服务，确保nginx服务启动，可用于提供服务
  	;;
  backup)
  	notify backup
  	systemctl start nginx
      ;;
  fault)
      notify fault
  	;;
  *)
  	echo "Usage: $(basename $0) {master|backup|fault}"
  	exit 1
  	;;
  esac
  
  #4.chk_down脚本：
  [root@nginx-lb01 keepalived]# cat /etc/keepalived/chk_down.sh 
  #!/bin/bash
  
  [[ ! -f /etc/keepalived/down ]]
  
  #5.增加执行权限：
  [root@nginx-lb01 keepalived]# chmod u+x chk_nginx.sh
  [root@nginx-lb01 keepalived]# chmod u+x notify.sh
  [root@nginx-lb01 keepalived]# chmod u+x chk_down.sh
  
  #5.重启keepalived服务：
  [root@nginx-lb01 keepalived]# systemctl restart keepalived.service
  
  #6.查看VIP情况：
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  

• nginx-lb02节点的keepalived部署如下：

  #1.keepalived配置文件：
  You have new mail in /var/spool/mail/root
  [root@nginx-lb02 keepalived]# cat /etc/keepalived/keepalived.conf
  ! Configuration File for keepalived
  
  global_defs {
     notification_email {
       root@localhost
     }
     notification_email_from keepalived@localhost
     smtp_server 127.0.0.1
     smtp_connect_timeout 30
     router_id keepalived01
     script_user root
     enable_script_security
     vrrp_mcast_group4 224.0.0.19
  }
  
  vrrp_script chk_down {
  	script "[[ ! -f /etc/keepalived/down ]]"    <==注意：在centos7.8测试使用这种方式无法生效。需要使用脚本方式。
  	weight -50
  	interval 1
  	fall 3
  	rise 3
  }
  
  vrrp_script chk_nginx {
  	script "/etc/keepalived/chk_nginx.sh"
  	interval 5
  }
  
  vrrp_instance VI_1 {
      state BACKUP
      interface eth1
      virtual_router_id 51
      priority 100
      advert_int 3
      authentication {
          auth_type PASS
          auth_pass 1111
      }
      virtual_ipaddress {
          192.168.20.28/24 dev eth1
      }
  
      track_interface {
      	eth2
  	eth0
      }
  
      track_script {
      	chk_down
  	chk_nginx
      }
  
      notify_master "/etc/keepalived/notify.sh master"
      notify_backup "/etc/keepalived/notify.sh backup"
      notify_fault "/etc/keepalived/notify.sh fault"
  }
  
  vrrp_instance VI_2 {
      state MASTER
      interface eth1
      virtual_router_id 52
      priority 120
      advert_int 3
      authentication {
          auth_type PASS
          auth_pass 2222
      }
      
      virtual_ipaddress {
          192.168.20.29/24 dev eth1
      }
      
      track_interface {
      	eth2
  	eth0
      }
  
      track_script {
      	chk_down
  	chk_nginx
      }
  
      notify_master "/etc/keepalived/notify.sh master"
      notify_backup "/etc/keepalived/notify.sh backup"
      notify_fault "/etc/keepalived/notify.sh fault"
  }
  
  #2.chk_nginx脚本文件：
  [root@nginx-lb02 keepalived]# cat /etc/keepalived/chk_nginx.sh 
  #!/bin/bash
  
  nginxpid=$(pidof nginx | wc -l) 
  
  #1.判断Nginx是否存活,如果不存活则尝试启动Nginx
  if [ $nginxpid -eq 0 ];then 
  	systemctl start nginx 
  	sleep 2 
  	
  	#2.等待2秒后再次获取一次Nginx状态 
  	nginxpid=$(pidof nginx | wc -l) 
  	
  	#3.再次进行判断, 如Nginx还不存活则停止Keepalived,让地址进行漂移,并退出脚本 
  	if [ $nginxpid -eq 0 ];then 
  		systemctl stop keepalived
  	fi 
  fi
  
  #3.notify.sh文件：
  [root@nginx-lb02 keepalived]# cat /etc/keepalived/notify.sh 
  #!/bin/bash
  
  contact='root@localhost'
  notify() {
  	local mailsubject="$(hostname) to be $1, vip floating"
  	local mailbody="$(date +'%F %T'): vrrp transition, $(hostname) changed to be $1"
  	echo "$mailbody" | mail -s "$mailsubject" $contact
  }
  
  case $1 in
  master)
      notify master
  	systemctl start nginx   <==keepalived状态切换时触发启动nginx服务，确保nginx服务启动，可用于提供服务
  	;;
  backup)
  	notify backup
  	systemctl start nginx
      ;;
  fault)
      notify fault
  	;;
  *)
  	echo "Usage: $(basename $0) {master|backup|fault}"
  	exit 1
  	;;
  esac
  
  #4.增加执行权限：
  [root@nginx-lb02 keepalived]# chmod u+x chk_nginx.sh
  [root@nginx-lb02 keepalived]# chmod u+x notify.sh
  
  #5.重启keepalived服务：
  [root@nginx-lb02 keepalived]# systemctl restart keepalived.service
  
  #6.查看VIP情况：
  [root@nginx-lb02 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:21:9d:5c brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.20/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.29/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::52b0:737b:a3cb:c6a5/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  

• 用客户端测试通过两个VIP访问后端WEB集群

  #测试VIP192.168.20.28，此时时通过负载均衡nginx-lb01节点访问
  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.28 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  
  #测试VIP192.168.20.29，此时时通过负载均衡nginx-lb02节点访问
  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.29 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  

1.5 测试监控的接口down后keepalived的情况

• 把nginx-lb01节点的eth2接口down掉，模拟连接内网的接口故障，此时若VIP不进行切换，则使用192.168.20.28地址的请求会出现问题。

  [root@nginx-lb01 keepalived]# ip link set eth2 down
  [root@nginx-lb01 keepalived]# ip link show eth2
  4: eth2: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
      link/ether 00:0c:29:33:71:da brd ff:ff:ff:ff:ff:ff
  

• 此时查看nginx-lb01节点的keepalived日志，发现keepalived状态切换为fault，192.168.20.28这个虚地址被移除，并发送通知消息。

  [root@nginx-lb01 ~]# tail -f /var/log/keepalived.log
  Jul  9 23:40:52 nginx-lb01 Keepalived_vrrp[1838]: Kernel is reporting: interface eth2 DOWN
  Jul  9 23:40:52 nginx-lb01 Keepalived_vrrp[1838]: VRRP_Instance(VI_1) Entering FAULT STATE
  Jul  9 23:40:52 nginx-lb01 Keepalived_vrrp[1838]: VRRP_Instance(VI_1) removing protocol VIPs.
  Jul  9 23:40:52 nginx-lb01 Keepalived_vrrp[1838]: Opening script file /etc/keepalived/notify.sh
  Jul  9 23:40:52 nginx-lb01 Keepalived_vrrp[1838]: VRRP_Instance(VI_1) Now in FAULT state
  Jul  9 23:40:54 nginx-lb01 Keepalived_vrrp[1838]: Kernel is reporting: interface eth2 DOWN
  Jul  9 23:40:54 nginx-lb01 Keepalived_vrrp[1838]: VRRP_Instance(VI_2) Now in FAULT state
  Jul  9 23:40:54 nginx-lb01 Keepalived_vrrp[1838]: Opening script file /etc/keepalived/notify.sh
  
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  You have new mail in /var/spool/mail/root
  

• 查看nginx-lb02节点的keepalived日志，发现它接管了192.168.20.28这个VIP，并发送通知消息。

  [root@nginx-lb02 ~]# tail -f /var/log/keepalived.log
  Jul  9 23:40:52 nginx-lb02 Keepalived_vrrp[1967]: VRRP_Instance(VI_1) Transition to MASTER STATE
  Jul  9 23:40:55 nginx-lb02 Keepalived_vrrp[1967]: VRRP_Instance(VI_1) Entering MASTER STATE
  Jul  9 23:40:55 nginx-lb02 Keepalived_vrrp[1967]: VRRP_Instance(VI_1) setting protocol VIPs.
  Jul  9 23:40:55 nginx-lb02 Keepalived_vrrp[1967]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul  9 23:40:55 nginx-lb02 Keepalived_vrrp[1967]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth1 for 192.168.20.28
  
  [root@nginx-lb02 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:21:9d:5c brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.20/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.29/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::52b0:737b:a3cb:c6a5/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  You have new mail in /var/spool/mail/root
  

• 此时测试192.168.20.28虚地址可以正常进行调度

  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.28 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  

• 恢复nginx-lb01的eth2口，虚地址192.168.20.28重新回到nginx-lb01节点

  [root@nginx-lb01 keepalived]# ip link set eth2 up
  
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  

1.6 测试nginx服务异常时keepalived的情况

• 把nginx-lb01节点的nginx服务停止，发现nginx很快就重新启动了，说明，检测nginx的脚本生效了。

  [root@nginx-lb01 keepalived]# systemctl stop nginx.service 
  
  [root@nginx-lb01 keepalived]# systemctl status nginx.service 
  ● nginx.service - nginx - high performance web server
     Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; vendor preset: disabled)
     Active: active (running) since Fri 2021-07-09 23:58:41 CST; 5s ago
       Docs: http://nginx.org/en/docs/
    Process: 2527 ExecStart=/usr/sbin/nginx -c /etc/nginx/nginx.conf (code=exited, status=0/SUCCESS)
    Process: 2526 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCESS)
   Main PID: 2529 (nginx)
     CGroup: /system.slice/nginx.service
             ├─2529 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
             └─2531 nginx: worker process
  
  Jul 09 23:58:41 nginx-lb01 systemd[1]: Starting nginx - high performance web server...
  Jul 09 23:58:41 nginx-lb01 nginx[2526]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
  Jul 09 23:58:41 nginx-lb01 nginx[2526]: nginx: configuration file /etc/nginx/nginx.conf test is successful
  Jul 09 23:58:41 nginx-lb01 systemd[1]: Failed to parse PID from file /var/run/nginx.pid: Invalid argument
  Jul 09 23:58:41 nginx-lb01 systemd[1]: Started nginx - high performance web server.
  

• 把nginx-lb01节点的nginx配置文件修改错误，然后再停止nginx服务，让nginx服务无法启动，此时查看nginx-lb01节点的keepalived日志，发现keepalived状态切换为fault，192.168.20.28这个虚地址被移除，并发送通知消息。

  [root@nginx-lb01 ~]# tail -f /var/log/keepalived.log 
  Jul 10 00:01:48 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127  <==脚本检测失败
  Jul 10 00:01:48 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Script(chk_nginx) failed   <==脚本检测失败
  Jul 10 00:01:49 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) Entering FAULT STATE  <==进入fault状态
  Jul 10 00:01:49 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) removing protocol VIPs.
  Jul 10 00:01:49 nginx-lb01 Keepalived_vrrp[2287]: Opening script file /etc/keepalived/notify.sh
  Jul 10 00:01:49 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) Now in FAULT state
  Jul 10 00:01:51 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_2) Now in FAULT state
  Jul 10 00:01:51 nginx-lb01 Keepalived_vrrp[2287]: Opening script file /etc/keepalived/notify.sh
  Jul 10 00:01:53 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127
  Jul 10 00:01:58 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127  <==每5s检测一次chk_nginx脚本
  Jul 10 00:02:03 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127
  Jul 10 00:02:08 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127
  Jul 10 00:02:13 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127
  Jul 10 00:02:18 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127
  Jul 10 00:02:23 nginx-lb01 Keepalived_vrrp[2287]: /etc/keepalived/chk_nginx.sh exited with status 127
  
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  

• 查看nginx-lb02节点的keepalived日志，发现它接管了192.168.20.28这个VIP，并发送通知消息。

  [root@nginx-lb02 ~]# tail -f /var/log/keepalived.log
  Jul 10 00:01:49 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) Transition to MASTER STATE
  Jul 10 00:01:52 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) Entering MASTER STATE
  Jul 10 00:01:52 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) setting protocol VIPs.
  Jul 10 00:01:52 nginx-lb02 Keepalived_vrrp[2208]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 00:01:52 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth1 for 192.168.20.28
  Jul 10 00:01:52 nginx-lb02 Keepalived_vrrp[2208]: Sending gratuitous ARP on eth1 for 192.168.20.28
  
  [root@nginx-lb02 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:21:9d:5c brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.20/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.29/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::52b0:737b:a3cb:c6a5/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  You have new mail in /var/spool/mail/root
  

• 此时测试192.168.20.28虚地址可以正常进行调度

  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.28 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  

• 此时恢复nginx-lb01节点的nginx配置文件，查看nginx-lb01节点的日志，发现chk_nginx脚本检测成功，nginx服务自动启动，虚地址192.168.20.28重新回到nginx-lb01节点

  [root@nginx-lb01 ~]# tail -f /var/log/keepalived.log
  Jul 10 00:07:43 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Script(chk_nginx) succeeded   <==脚本检测成功
  Jul 10 00:07:44 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) Entering BACKUP STATE
  Jul 10 00:07:44 nginx-lb01 Keepalived_vrrp[2287]: Opening script file /etc/keepalived/notify.sh
  Jul 10 00:07:45 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_2) Entering BACKUP STATE
  Jul 10 00:07:45 nginx-lb01 Keepalived_vrrp[2287]: Opening script file /etc/keepalived/notify.sh
  Jul 10 00:07:47 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) forcing a new MASTER election
  Jul 10 00:07:50 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) Transition to MASTER STATE
  Jul 10 00:07:53 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) Entering MASTER STATE
  Jul 10 00:07:53 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) setting protocol VIPs.
  Jul 10 00:07:53 nginx-lb01 Keepalived_vrrp[2287]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 00:07:53 nginx-lb01 Keepalived_vrrp[2287]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth1 for 192.168.20.28
  Jul 10 00:07:53 nginx-lb01 Keepalived_vrrp[2287]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 00:07:53 nginx-lb01 Keepalived_vrrp[2287]: Sending gratuitous ARP on eth1 for 192.168.20.28
  
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  
  [root@nginx-lb01 keepalived]# systemctl status nginx.service 
  ● nginx.service - nginx - high performance web server
     Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; vendor preset: disabled)
     Active: active (running) since Sat 2021-07-10 00:07:41 CST; 2min 48s ago
       Docs: http://nginx.org/en/docs/
    Process: 3758 ExecStart=/usr/sbin/nginx -c /etc/nginx/nginx.conf (code=exited, status=0/SUCCESS)
    Process: 3757 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCESS)
   Main PID: 3760 (nginx)
     CGroup: /system.slice/nginx.service
             ├─3760 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
             └─3762 nginx: worker process
  

• nginx-lb02节点移除虚地址192.168.20.28，进入BACKUP状态

  [root@nginx-lb02 ~]# tail -f /var/log/keepalived.log
  Jul 10 00:07:47 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) Received advert with higher priority 120, ours 100
  Jul 10 00:07:47 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) Entering BACKUP STATE
  Jul 10 00:07:47 nginx-lb02 Keepalived_vrrp[2208]: VRRP_Instance(VI_1) removing protocol VIPs.
  Jul 10 00:07:47 nginx-lb02 Keepalived_vrrp[2208]: Opening script file /etc/keepalived/notify.sh
  

1.7 测试chk_down脚本生效后keepalived的情况

• 在nginx-lb01节点创建/etc/keepalived/down文件

  #1.创建down文件：
  [root@nginx-lb01 keepalived]# touch down
  
  #2.查看nginx-lb01节点的keepalived日志，脚本加测失败，降低本节点vrrp优先级，变为BACKUP状态：
  [root@nginx-lb01 ~]# tail -f /var/log/keepalived.log 
  Jul 10 16:20:28 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1  <==三次脚本退出状态为1
  Jul 10 16:20:29 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:30 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:30 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Script(chk_down) failed    <==判定脚本检测失败
  Jul 10 16:20:31 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Changing effective priority from 120 to 70 <==减少vrrp优先级50
  Jul 10 16:20:31 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_2) Changing effective priority from 100 to 50 <==减少vrrp优先级50
  Jul 10 16:20:31 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:32 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:33 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:34 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 70
  Jul 10 16:20:34 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Entering BACKUP STATE   <==进入BACKUP状态
  Jul 10 16:20:34 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) removing protocol VIPs.
  Jul 10 16:20:34 nginx-lb01 Keepalived_vrrp[18592]: Opening script file /etc/keepalived/notify.sh
  Jul 10 16:20:34 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:35 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:36 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:37 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  Jul 10 16:20:38 nginx-lb01 Keepalived_vrrp[18592]: /etc/keepalived/chk_down.sh exited with status 1
  
  #3.本机虚ip移除：
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  

• 查看nginx-lb02节点的情况

  #1.查看日志情况，该节点称为MASTER状态，接管了虚IP192.168.20.28
  [root@nginx-lb02 ~]# tail -f /var/log/keepalived.log
  Jul 10 16:20:34 nginx-lb02 Keepalived_vrrp[3831]: VRRP_Instance(VI_1) forcing a new MASTER election
  Jul 10 16:20:37 nginx-lb02 Keepalived_vrrp[3831]: VRRP_Instance(VI_1) Transition to MASTER STATE
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: VRRP_Instance(VI_1) Entering MASTER STATE
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: VRRP_Instance(VI_1) setting protocol VIPs.
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth1 for 192.168.20.28
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:40 nginx-lb02 Keepalived_vrrp[3831]: Opening script file /etc/keepalived/notify.sh
  Jul 10 16:20:45 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:45 nginx-lb02 Keepalived_vrrp[3831]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth1 for 192.168.20.28
  Jul 10 16:20:45 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:45 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:20:45 nginx-lb02 Keepalived_vrrp[3831]: Sending gratuitous ARP on eth1 for 192.168.20.28
  
  #2.本机虚IP情况：
  [root@nginx-lb02 ~]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:21:9d:5c brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.20/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.29/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::52b0:737b:a3cb:c6a5/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever
  
  

• 此时测试192.168.20.28虚地址可以正常进行调度

  [root@xuzhichao ~]# for i in {1..10} ;do curl -k -Hhost:www.xuzhichao.com https://192.168.20.28 ;done
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  node1.xuzhichao.com page
  node2.xuzhichao.com page
  

• 在nginx-lb01节点删除down文件：

  #1.删除down文件：
  [root@nginx-lb01 keepalived]# rm -f /etc/keepalived/down 
  
  #2.查看nginx-lb01节点日志，显示脚本校测成功，优先级恢复，重新抢占会虚地址192.168.20.28
  [root@nginx-lb01 ~]# tail -f /var/log/keepalived.log 
  Jul 10 16:33:56 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Script(chk_down) succeeded
  Jul 10 16:33:57 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_2) Changing effective priority from 50 to 100
  Jul 10 16:33:57 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Changing effective priority from 70 to 120
  Jul 10 16:33:59 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) forcing a new MASTER election
  Jul 10 16:34:02 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Transition to MASTER STATE
  Jul 10 16:34:05 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Entering MASTER STATE
  Jul 10 16:34:05 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) setting protocol VIPs.
  Jul 10 16:34:05 nginx-lb01 Keepalived_vrrp[18592]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:34:05 nginx-lb01 Keepalived_vrrp[18592]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth1 for 192.168.20.28
  Jul 10 16:34:05 nginx-lb01 Keepalived_vrrp[18592]: Sending gratuitous ARP on eth1 for 192.168.20.28
  Jul 10 16:34:05 nginx-lb01 Keepalived_vrrp[18592]: Sending gratuitous ARP on eth1 for 192.168.20.28
  
  #3.本机虚IP情况：
  [root@nginx-lb01 keepalived]# ip add show eth1
  3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether 00:0c:29:33:71:d0 brd ff:ff:ff:ff:ff:ff
      inet 192.168.20.19/24 brd 192.168.20.255 scope global noprefixroute eth1
         valid_lft forever preferred_lft forever
      inet 192.168.20.28/24 scope global secondary eth1
         valid_lft forever preferred_lft forever
      inet6 fe80::f0da:450f:5a80:de8b/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::7f20:c9d7:cb3e:bb8e/64 scope link tentative noprefixroute dadfailed 
         valid_lft forever preferred_lft forever
      inet6 fe80::1a77:baea:91d8:79c7/64 scope link noprefixroute 
         valid_lft forever preferred_lft forever