1. Keepalived的安装

1.1. yum install方式

  1. yum install -y keepalived

1.2. 安装包编译方式

更多安装包参考：http://www.keepalived.org/download.html

  1. wget http://www.keepalived.org/software/keepalived-2.0.7.tar.gz
  2. tar zxvf keepalived-2.0.7.tar.gz
  3. cd keepalived-2.0.7
  4. ./configure --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc --mandir=/usr/share
  5. make && make install

2. 常用配置

keepalived配置文件路径：/etc/keepalived/keepalived。

2.1. MASTER（主机配置）

  1. global_defs {
  2.     router_id proxy-keepalived
  3. }
  5. vrrp_script check_nginx {
  6.     script "/etc/keepalived/scripts/check_nginx.sh" 
  7.     interval 3  
  8.     weight 2   
  9. }
  11. vrrp_instance VI_1 {
  12.     state BACKUP
  13.     interface eth2
  14.     virtual_router_id 15
  15.     priority 100
  16.     advert_int 1
  17.     authentication {
  18.         auth_type PASS
  19.         auth_pass xxx
  20.     }
  21.     track_script {
  22.         check_nginx 
  23.     }
  24.     virtual_ipaddress {
  25.         180.101.115.139
  26.         218.98.38.29
  27.     }
  29.     nopreempt
  31.     notify_master "/etc/keepalived/keepalived_notify.sh master"
  32.     notify_backup "/etc/keepalived/keepalived_notify.sh backup"
  33.     notify_fault "/etc/keepalived/keepalived_notify.sh fault"
  34.     notify_stop "/etc/keepalived/keepalived_notify.sh stop"
  35. }

2.2. BACKUP（备机配置）

  1. global_defs {
  2.     router_id proxy-keepalived
  3. }
  5. vrrp_script check_nginx {
  6.     script "/etc/keepalived/scripts/check_nginx.sh" 
  7.     interval 3  
  8.     weight 2   
  9. }
  11. vrrp_instance VI_1 {
  12.     state BACKUP 
  13.     interface eth2
  14.     virtual_router_id 15
  15.     priority 99
  16.     advert_int 1
  17.     authentication {
  18.         auth_type PASS
  19.         auth_pass xxx
  20.     }
  21.     track_script {
  22.         check_nginx 
  23.     }
  24.     virtual_ipaddress {
  25.         180.101.115.139
  26.         218.98.38.29
  27.     }
  29.     nopreempt
  31.     notify_master "/etc/keepalived/keepalived_notify.sh master"
  32.     notify_backup "/etc/keepalived/keepalived_notify.sh backup"
  33.     notify_fault "/etc/keepalived/keepalived_notify.sh fault"
  34.     notify_stop "/etc/keepalived/keepalived_notify.sh stop"
  35. }

3. 注意事项

1、指定Nginx健康检测脚本：/etc/keepalived/scripts/check_nginx.sh

2、主备配置差别主要为（建议这么配置）：

以下两种方式的配置，当其中一台机器keepalived挂掉后会自动VIP切到另一台机器，当挂掉机器keepalived恢复后不会抢占VIP，该方式可以避免机器恢复再次切VIP所带来的影响。

  • 主机:(state BACKUP;priority 100)
  • 备机：(state BACKUP;priority 99)

  • 非抢占：nopreempt

    或者：

  • 主机:(state MASTER;priority 100)

  • 备机：(state BACKUP;priority 100)
  • 默认抢占

3、指定VIP

  1.     virtual_ipaddress {
  2.         180.101.115.139
  3.         218.98.38.29
  4.     }

4、可以指定为非抢占：nopreempt，即priority高不会抢占已经绑定VIP的机器。

5、制定绑定IP的网卡： interface eth2

6、可以指定keepalived状态变化通知

  1.     notify_master "/etc/keepalived/keepalived_notify.sh master"
  2.     notify_backup "/etc/keepalived/keepalived_notify.sh backup"
  3.     notify_fault "/etc/keepalived/keepalived_notify.sh fault"
  4.     notify_stop "/etc/keepalived/keepalived_notify.sh stop"

7、virtual_router_id 15值，主备值一致，但建议不应与集群中其他Nginx机器上的相同，如果同一个网段配置的virtual_router_id 重复则会报错，选择一个不重复的0~255之间的值，可以用以下命令查看已存在的vrid。

  1. tcpdump -nn -i any net 224.0.0.0/8

4. 常用脚本

4.1. Nginx健康检测脚本

在Nginx配置目录下（/etc/nginx/conf.d/）增加health.conf的配置文件,该配置文件用于配置Nginx health的接口。

  1. server {
  2.     listen       80  default_server;
  3.     server_name  localhost;
  4.     default_type text/html;
  5.     return 200 'Health';  
  6. }

Nginx健康检测脚本：/etc/keepalived/scripts/check_nginx.sh

4.1.1. 检查接口调用是否为200

  1. #!/bin/sh
  2. set -x
  4. timeout=30 #指定默认30秒没返回200则为非健康，该值可根据实际调整
  6. if [ -n ${timeout} ];then
  7.     httpcode=`curl -sL -w %{http_code} -m ${timeout} http://localhost -o /dev/null`
  8. else
  9.     httpcode=`curl -sL -w %{http_code}  http://localhost -o /dev/null`
  10. fi
  12. if [ ${httpcode} -ne 200 ];then
  13.         echo `date`':  nginx is not healthy, return http_code is '${httpcode} >> /etc/keeperalived/keepalived.log
  14.         killall keepalived
  15.         exit 1
  16. else
  17.         exit 0
  18. fi

4.1.2. 检查Nginx进程是否运行

  1. #!/bin/sh
  2. if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
  3.         echo "$(date) nginx pid not found">>/etc/keepalived/keepalived.log
  4.         killall keepalived
  5. fi

4.2. Keepalived状态通知脚本

  1. #!/bin/bash
  2. set -x
  4. warn_receiver=$1
  5. ip=$(ifconfig bond0|grep inet |awk '{print $2}')
  6. warningInfo="${ip}_keepalived_changed_status_to_$1"
  7. warn-report --user admin --key=xxxx --target=${warn_receiver} ${warningInfo}
  8. echo $(date)  $1 >> /etc/keepalived/status

说明：

  1. ip获取本机IP，本例中IP获取是bond0的IP，不同机器网卡名称不同需要修改为对应网卡名称。
  2. 告警工具根据自己指定。