keepalived利用VRRP Script进行资源监控

2024-01-05 21:44:28

一 VRRP Script设置

1.1 定义vrrp script脚本

vrrp script：自定义资源监控脚本，vrrp实例根据脚本返回值，公共定义，可被多个实例调用，定义在vrrp实例之外的独立配置模块。一般放在global_def设置块之后，是和global_defs平级的语句块。

通常此脚本用于监控指定应用的状态，一旦发现应用的状态异常，则触发对master节点的权重见至低于slave节点，从而实现VIP切换到slave节点。

vrrp_script <SCRIPT_NAME> {          #定义一个检测脚本，在global_defs之外配置
	script <string>|<quoted-string>  #shell命令或脚本路径
    interval <integer>               #间隔时间，单位为妙，默认1s
    timeout <integer>                #超时时间
	weiht <integer:-254..254>        #默认为0，如果设置此值为负数，当上面脚本返回值为非0时，会将此值与本节点权重相加可以降低节点权重，即fall.ruguo为正数，当脚本返回值为0，会将此值与本节点权重相加可以提高节点权重，即标识rise，通常使用负值。
    fall <integer>                   #执行脚本连续几次都失败，则转换为失败，建议设置2以上
    rise <integer>                   #执行脚本连续几次都成功，把服务器从失败标记为成功
    user USERNAME [GROUPNAME]        #执行检测脚本的用户或组
    init_fail                        #设置默认标记为失败状态，检测成功后再转换为成功状态
}

1.2 调用vrrp script

vrrp_instance VI_1 {
   ....
   track_script {
       <SCRIPT_NAME>
   }
}

二利用脚本实现主从切换

2.1 修改keepalived配置文件

2.1.1 设置node-01配置文件

点击查看代码

root@node-01:~# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { 1304005320@qq.com } notification_email_from 1304005320@qq.com smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id node-01 vrrp_skip_check_adv_addr vrrp_strict vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_script chk_down { script "/etc/keepalived/check_down.sh" #返回非0，触发权重-30 interval 1 weight -30 fall 3 rise 2 timeout 2 }

vrrp_instance VI_1 { state MASTER #node-02 为BACKUP interface ens33 virtual_router_id 101 priority 100 #node-02 为80 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.174.20 } notify_master "/etc/keepalived/notify.sh master" notify_backup "/etc/keepalived/notify.sh backup" notify_fault "/etc/keepalived/notify.sh fault" track_script { chk_down } }

2.2 创建check_down.sh

root@node-01:~# cat /etc/keepalived/check_down.sh
#!/bin/bash
[ ! -f /etc/keepalived/down ]

2.3 验证主从切换

2.3.1 查看node-01状态

root@node-01:~# hostname -I
192.168.174.120 192.168.174.20

2.3.2 创建down文件

root@node-01:~# touch /etc/keepalived/down

2.3.3 验证node-01状态

root@node-01:~# hostname -I
192.168.174.120

2.3.4 查看日志

root@node-01:~# tail -f /var/log/syslog |grep  Keepalived
Nov  9 20:48:48 node-01 Keepalived_vrrp[7438]: VRRP_Script(chk_down) failed (exited with status 1)
Nov  9 20:48:48 node-01 Keepalived_vrrp[7438]: (VI_1) Changing effective priority from 100 to 70
Nov  9 20:48:51 node-01 Keepalived_vrrp[7438]: (VI_1) Master received advert from 192.168.174.121 with higher priority 80, ours 70
Nov  9 20:48:51 node-01 Keepalived_vrrp[7438]: (VI_1) Entering BACKUP STATE
Nov  9 20:48:51 node-01 Keepalived_vrrp[7438]: (VI_1) removing VIPs.

2.3.5 删除down文件

root@node-01:~# rm -rf /etc/keepalived/down

2.3.6 查看vip状态

root@node-01:~# hostname -I
192.168.174.120 192.168.174.20

2.3.7 查看VIP切换日志

root@node-01:~# tail -f /var/log/syslog |grep  Keepalived
Nov  9 20:53:10 node-01 Keepalived_vrrp[7438]: Script `chk_down` now returning 0
Nov  9 20:53:11 node-01 Keepalived_vrrp[7438]: VRRP_Script(chk_down) succeeded
Nov  9 20:53:11 node-01 Keepalived_vrrp[7438]: (VI_1) Changing effective priority from 70 to 100
Nov  9 20:53:11 node-01 Keepalived_vrrp[7438]: (VI_1) received lower priority (80) advert from 192.168.174.121 - discarding
Nov  9 20:53:13 node-01 Keepalived_vrrp[7438]: message repeated 2 times: [ (VI_1) received lower priority (80) advert from 192.168.174.121 - discarding]
Nov  9 20:53:14 node-01 Keepalived_vrrp[7438]: (VI_1) Receive advertisement timeout
Nov  9 20:53:14 node-01 Keepalived_vrrp[7438]: (VI_1) Entering MASTER STATE
Nov  9 20:53:14 node-01 Keepalived_vrrp[7438]: (VI_1) setting VIPs.
Nov  9 20:53:14 node-01 Keepalived_vrrp[7438]: (VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.174.20
Nov  9 20:53:14 node-01 Keepalived_vrrp[7438]: Sending gratuitous ARP on ens33 for 192.168.174.20
Nov  9 20:53:14 node-01 Keepalived_vrrp[7438]: message repeated 4 times: [ Sending gratuitous ARP on ens33 for 192.168.174.20]
Nov  9 20:53:19 node-01 Keepalived_vrrp[7438]: (VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.174.20
Nov  9 20:53:19 node-01 Keepalived_vrrp[7438]: Sending gratuitous ARP on ens33 for 192.168.174.20
Nov  9 20:53:19 node-01 Keepalived_vrrp[7438]: message repeated 4 times: [ Sending gratuitous ARP on ens33 for 192.168.174.20]

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