一 VRRP Script設定

1.1 定義vrrp script指令碼

vrrp script：自定義資源監控指令碼，vrrp例項根據指令碼返回值，公共定義，可被多個例項呼叫，定義在vrrp例項之外的獨立配置模組。一般放在global_def設定塊之後，是和global_defs平級的語句塊。

通常此指令碼用於監控指定應用的狀態，一旦發現應用的狀態異常，則觸發對master節點的權重見至低於slave節點，從而實現VIP切換到slave節點。

vrrp_script <SCRIPT_NAME> {          #定義一個檢測指令碼，在global_defs之外配置
	script <string>|<quoted-string>  #shell命令或指令碼路徑
    interval <integer>               #間隔時間，單位為妙，預設1s
    timeout <integer>                #超時時間
	weiht <integer:-254..254>        #預設為0，如果設定此值為負數，當上面指令碼返回值為非0時，會將此值與本節點權重相加可以降低節點權重，即fall.ruguo為正數，當指令碼返回值為0，會將此值與本節點權重相加可以提高節點權重，即標識rise，通常使用負值。
    fall <integer>                   #執行指令碼連續幾次都失敗，則轉換為失敗，建議設定2以上
    rise <integer>                   #執行指令碼連續幾次都成功，把伺服器從失敗標記為成功
    user USERNAME [GROUPNAME]        #執行檢測指令碼的使用者或組
    init_fail                        #設定預設標記為失敗狀態，檢測成功後再轉換為成功狀態
}
 

1.2 呼叫vrrp script

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

二 利用指令碼實現主從切換

2.1 修改keepalived配置檔案

2.1.1 設定node-01配置檔案

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，觸發權重-30

interval 1

weight -30

fall 3

rise 2

timeout 2

}
vrrp_instance VI_1 {

state MASTER     #node-02 為BACKUP

interface ens33

virtual_router_id 101

priority 100     #node-02 為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 建立check_down.sh

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

2.3 驗證主從切換

2.3.1 檢視node-01狀態

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

2.3.2 建立down檔案

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

2.3.3 驗證node-01狀態

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

2.3.4 檢視日誌

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 刪除down檔案

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

2.3.6 檢視vip狀態

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

2.3.7 檢視VIP切換日誌

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]