keepalived利用VRRP Script进行资源监控

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

root@node-01:~# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {

notification_email {

[email protected]

}

notification_email_from [email protected]

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]