实战案例：实现 VIP高可用

[root@ka1-centos8 ~]#cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
    global_defs {
        notification_email {
        root@localhost
        }
    notification_email_from kaadmin@localhost
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id ka1.magedu.org            #在另一个节点为ka2.magedu.org
    vrrp_mcast_group4 224.0.100.100
}

vrrp_script check_down {
    script "[ ! -f /etc/keepalived/down ]" #/etc/keepalived/down存在时返回非0，触发权重-30
    interval 1
    weight -30
    fall 3
    rise 2
    timeout 2
}

vrrp_instance VI_1 {
    state MASTER                #在另一个节点为BACKUP
    interface eth0
    virtual_router_id 66
    priority 100                #在另一个节点为80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        10.0.0.10/24 dev eth0 label eth0:1
    }
    track_interface {
        eth0
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
    track_script {
       check_down           #调用前面定义的脚本
   }
}

[root@ka1-centos8 ~]#touch /etc/keepalived/down
[root@ka1-centos8 ~]#tail -f /var/log/messages 
Mar 28 19:47:03 ka1-centos8 Keepalived_vrrp[7200]: Script check_down now returning 1
Mar 28 19:47:05 ka1-centos8 Keepalived_vrrp[7200]: VRRP_Script(chk_down) failed (exited with status 1)
Mar 28 19:47:05 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Changing effective priority from 100 to 70
Mar 28 19:47:07 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Master received advert from 10.0.0.18 with higher priority 80, ours 70
Mar 28 19:47:07 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Entering BACKUP STATE
Mar 28 19:47:07 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) removing VIPs.
[root@rs1 ~]#tcpdump -i eth0 -nn 224.0.100.100
19:42:09.578203 IP 10.0.0.8 > 224.0.100.100: VRRPv2, Advertisement, vrid 66, prio 100, authtype simple, intvl 1s, length 20
19:42:10.579304 IP 10.0.0.8 > 224.0.100.100: VRRPv2, Advertisement, vrid 66, prio 70, authtype simple, intvl 1s, length 20

[root@ka1-centos8 ~]#rm -f  /etc/keepalived/down
[root@ka1-centos8 ~]#tail -f /var/log/messages 
Mar 28 19:47:45 ka1-centos8 Keepalived_vrrp[7200]: Script check_down now returning 0
Mar 28 19:47:46 ka1-centos8 Keepalived_vrrp[7200]: VRRP_Script(check_down) succeeded
Mar 28 19:47:46 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Changing effective priority from 70 to 100
Mar 28 19:47:46 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) received lower priority (80) advert from 10.0.0.18 - discarding
Mar 28 19:47:47 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) received lower priority (80) advert from 10.0.0.18 - discarding
Mar 28 19:47:48 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) received lower priority (80) advert from 10.0.0.18 - discarding
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Receive advertisement timeout
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Entering MASTER STATE
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) setting VIPs.
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: Sending gratuitous ARP on eth0 for 10.0.0.10
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: (VI_1) Sending/queueing gratuitous ARPs on eth0 for 10.0.0.10
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: Sending gratuitous ARP on eth0 for 10.0.0.10
Mar 28 19:47:49 ka1-centos8 Keepalived_vrrp[7200]: Sending gratuitous ARP on eth0 for 10.0.0.10
[root@rs1 ~]#tcpdump -i eth0 -nn 224.0.100.100
19:49:16.199462 IP 10.0.0.18 > 224.0.100.100: VRRPv2, Advertisement, vrid 66, prio 80, authtype simple, intvl 1s, length 20
19:49:17.199897 IP 10.0.0.18 > 224.0.100.100: VRRPv2, Advertisement, vrid 66, prio 80, authtype simple, intvl 1s, length 20
19:49:17.810376 IP 10.0.0.8 > 224.0.100.100: VRRPv2, Advertisement, vrid 66, prio 100, authtype simple, intvl 1s, length 20
19:49:18.811048 IP 10.0.0.8 > 224.0.100.100: VRRPv2, Advertisement, vrid 66, prio 100, authtype simple, intvl 1s, length 20

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