keepalived 监控通知 keepalived 状态

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mob6454cc7aaa9d 2024-04-05 12:23:29

文章标签 keepalived 监控通知服务器 vim ip地址 文章分类 运维

keepalived简介：

keepalived是集群管理中保证高可用的一个服务软件，用来防止单点故障。
keepalived的作用是监测服务器的状态，如果有一台服务器岩机，并将有故障的服务器从系统中剔除，同时使用其他服务器代替该服务器工作。

keepalived服务介绍：

起初的设计是专门给LVS服务的，专门用来监控LVS集群系统中各个服务节点的状态，后来又加入了VRRP（Virtual Router
Redundancy
Protocol）虚拟路由器冗余协议，VRRP是为了解决静态路由单点故障，它有两大功能：健康检查与故障切换（主备之间快速切换） HA的功能：
在主备LB之间相互监控运行状态，一旦主LB宕机，备LB会立马接收主LB的所有资源（IP资源与VIP资源），然后接管主LB来运行LB的功能，一旦主LB恢复，它将资源还给主LB
健康检查：主要是对RS节点的运行健康性检查，一旦有节点宕机，它会不再将主求发给这个RS节点

keepalived工作原理：

keepalived是以VRRP为实现基础的，即虚拟路由冗余协议；
虚拟路由冗余协议：可以认为是实现路由器高可用的协议，即将多个提供相同功能的路由器组成一个路由器组，这个组里面有master和backup，master上面有一个对外服务的vip地址，master会发组播，当backup收不到vrrp包时就认为master岩机了，这时就需要根据vrrp的优先级选举出一个backup当master，这样就实现了高可用。

keepalived主要有三个模块是core、check和vrrp。core模块为keepalived的核心，负责主进程的启动、维护以及全局配置文件的加载和解析。check负责健康检查，包括常见的各种检查方式。vrrp模块是来实现VRRP协议的。

keepalived相关组件：

vrrp stack  实现vrrp虚拟ip
checkers   负责后端服务器的健康监测。
ipvs  wrapper-----ipvs   对lvs的实现高可用架构。能够根据配置文件自动生成ipvs规则。

keepalived的配置文件介绍：在这我只选择了前两段进行详细说明。

! Configuration File for keepalived

global_defs {           全局段，主要是配置故障发生时的通知对象及主机标识
   notification_email {         告警邮件。
     acassen@firewall.loc       这有三个实列，表示将告警邮件发给谁。
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc   表示发件人。
   smtp_server 192.168.200.1    表示发件人使用的服务器。
   smtp_connect_timeout 30      表示连接服务器的超时时间。
   router_id LVS_DEVEL          表示标识唯一主机，通常为hostname
  
}

vrrp_instance VI_1 {           vrrp_instance区域用来定义对外提供服务的vip区域及相关属性。
    state MASTER               表示这台主机的虚拟IP为主节点。
    interface eth0
    virtual_router_id 51       虚拟地址id标识。
    priority 100               虚拟ip的在这台主机的优先级。
    advert_int 1               每个多长时间发送心跳信息广播包，告诉备份主机的存活状态
    authentication {           认证模式。
        auth_type PASS
        auth_pass 8ab998cd    认证密码可随机生成。

    }
    virtual_ipaddress {
        192.168.200.16        这些都是用于游离的虚拟地址。
        192.168.200.17
        192.168.200.18
    }
}

**keepalived的实现配置。
配置前提：

1，本机的主机名，要和hostname（uname -n）获得的名称保持一致。；
        centos6：/etc/sysconfig/network
        centos7：hostnamectl  set-hostname   hostname

2，各节点要互相解析主机名；一般建议通过hosts文件进行解析。

3，确保iptables及selinux不会成为服务阻碍；

两台主机，两台主机尽量时间同步。

node3	node1
10.5.100.183	10.2.100.207

NODE3节点
一：安装keepalived软件包

[root@node3 ~]# yum install keepalived -y

[root@node3 ~]# cd /etc/keepalived/
[root@node3 keepalived]# ls
keepalived.back  keepalived.conf
[root@node3 keepalived]# vim keepalived.conf 
[root@node3 keepalived]# 

! Configuration File for keepalived
 
global_defs {
       root@localhost
   }
   notification_email_from kaadmin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node3.yan.com
   vrrp_mcast_group 224.18.0.100      设置组播地址，只能在这个组播域内
}
 
vrrp_instance VI_1 { 
    state MASTER
    interface enp4s0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 8ab998cd
    }
    virtual_ipaddress { 
        10.5.100.80/24 
    }
}

[root@node3 keepalived]# scp keepalived.conf node1:/etc/keepalived/
[root@node3 ~]# systemctl restart keepalived

NODE1节点：

[root@node1 ~]# vim /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 node1.yan.com   修改主机名称
   vrrp_mcast_group 224.18.0.100
}

vrrp_instance VI_1 {
    state backup
    interface eno16777736    修改网卡设备
    virtual_router_id 51
    priority 98              修改成backup变为备用主机
    advert_int 1 
    authentication {
        auth_type PASS
        auth_pass 8ab998cd
    }
    virtual_ipaddress {
        10.5.100.80/24
    }
}
[root@node3 ~]# systemctl restart keepalived   重启keepalived服务

验证keepalived的高可用架构。

[root@node3 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 74:27:ea:e6:54:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.183/24 brd 10.5.100.255 scope global noprefixroute dynamic enp4s0
       valid_lft 585886sec preferred_lft 585886sec
    inet 10.5.100.80/24 scope global secondary enp4s0    虚拟ip地址已经在node3主节点。
       valid_lft forever preferred_lft forever
    inet6 fe80::477d:49ca:2e17:2bf1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@node3 ~]# 
     node1是没有虚拟游离ip地址的。
[root@node1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:d0:83:ae brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.207/24 brd 10.5.100.255 scope global dynamic eno16777736
       valid_lft 580437sec preferred_lft 580437sec
    inet6 fe80::20c:29ff:fed0:83ae/64 scope link 
       valid_lft forever preferred_lft forever

现在我把NODE3节点keepalived挂掉。看游离地址的转换。

[root@node3 ~]# systemctl stop keepalived
[root@node3 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 74:27:ea:e6:54:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.183/24 brd 10.5.100.255 scope global noprefixroute dynamic enp4s0
       valid_lft 583952sec preferred_lft 583952sec
    inet6 fe80::477d:49ca:2e17:2bf1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@node3 ~]# 
[root@node1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:d0:83:ae brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.207/24 brd 10.5.100.255 scope global dynamic eno16777736
       valid_lft 578546sec preferred_lft 578546sec
    inet 10.5.100.80/24 scope global secondary eno16777736   查看虚拟地址ip已经转化过来了
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fed0:83ae/64 scope link 
       valid_lft forever preferred_lft forever

当我们在把node3节点启动时，游离虚拟ip地址又会转换成到node3节点，因为node3节点优先级高。

[root@node3 ~]# systemctl restart keepalived
[root@node3 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 74:27:ea:e6:54:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.183/24 brd 10.5.100.255 scope global noprefixroute dynamic enp4s0
       valid_lft 583700sec preferred_lft 583700sec
    inet 10.5.100.80/24 scope global secondary enp4s0
       valid_lft forever preferred_lft forever
    inet6 fe80::477d:49ca:2e17:2bf1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@node1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:d0:83:ae brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.207/24 brd 10.5.100.255 scope global dynamic eno16777736
       valid_lft 578273sec preferred_lft 578273sec
    inet6 fe80::20c:29ff:fed0:83ae/64 scope link 
       valid_lft forever preferred_lft forever

设定脚本在不关闭keepalived服务情况下自动切换主备节点。

[root@node3 ~]# vim /etc/keepalived/keepalived.conf 
! Configuration File for keepalived
 
global_defs {
       root@localhost
   }
   notification_email_from kaadmin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node3.yan.com
   vrrp_mcast_group 224.18.0.100
}
 
vrrp_script chk_yan {    脚本设定区域
   script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"  判断语句当down文件存在时
   interval 1    表示测试一次。 
   weight -2     文件存在时就自动降低优先级2个成为备节点。
}        
        
vrrp_instance VI_1 {
    state MASTER
    interface enp4s0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication { 
        auth_type PASS
        auth_pass 8ab998cd
    }
    virtual_ipaddress {
        10.5.100.80/24 
    }
     
    track_script {        调用这个脚本。
        chk_yan
    }
}

[root@node3 ~]# systemctl restart keepalived

NODE1节点配置脚本，跟上述节点配置一样。

[root@node1 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
       root@localhost
   }
   notification_email_from kaadmin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node3.yan.com
   vrrp_mcast_group 224.18.0.100
}

vrrp_script chk_yan {
   script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
   interval 1
   weight -2
}
vrrp_instance VI_1 {
    state MASTER
    interface enp4s0
    virtual_router_id 51
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 8ab998cd
    }
    virtual_ipaddress {
        10.5.100.80/24 
    }
    
    track_script {
        chk_yan
    }
}
[root@node3 ~]# systemctl restart keepalived

创建和删除down文件，在node3节点进行验证。

[root@node3 keepalived]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 74:27:ea:e6:54:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.183/24 brd 10.5.100.255 scope global noprefixroute dynamic enp4s0
       valid_lft 581140sec preferred_lft 581140sec
    inet 10.5.100.80/24 scope global secondary enp4s0
       valid_lft forever preferred_lft forever
    inet6 fe80::477d:49ca:2e17:2bf1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@node3 keepalived]# touch  down
[root@node3 keepalived]# ls
down  keepalived.back  keepalived.conf
[root@node3 keepalived]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 74:27:ea:e6:54:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.183/24 brd 10.5.100.255 scope global noprefixroute dynamic enp4s0
       valid_lft 582177sec preferred_lft 582177sec
    inet6 fe80::477d:49ca:2e17:2bf1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@node3 keepalived]# rm -rf down 
[root@node3 keepalived]# ls
keepalived.back  keepalived.conf
[root@node3 keepalived]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 74:27:ea:e6:54:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.5.100.183/24 brd 10.5.100.255 scope global noprefixroute dynamic enp4s0
       valid_lft 582168sec preferred_lft 582168sec
    inet 10.5.100.80/24 scope global secondary enp4s0
       valid_lft forever preferred_lft forever
    inet6 fe80::477d:49ca:2e17:2bf1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

在两个节点定义一个脚本实现，在主节点和备节点发生切换的时候各自发送状态邮件。
NODE1节点

[root@node1 keepalived]# vim notify.sh 
#!/bin/bash
vip=10.5.100.88
contact='root@localhost'

notify() {
      mailsubject="`hostname` to be $1: $vip floating"
      mailbody="`date '+%F %H:%M:%S'`: vrrp transition, `hostname` change to be $1"
      echo $mailbody | mail -s "$mailsubject" $contact
}

case "$1" in
      master)
        notify master
        exit 0 
        ;;
      backup)
        notify backup
        exit 0
        ;;
      fault)
        notify fault
        exit 0
        ;;
         *)
        echo 'usage:`basename $0` {master|backup|fault}'
        exit 1
        ;;
esac
[root@node1 keepalived]# scp notify.sh node3:/etc/keepalived/  将脚本传送给备用节点。

二：定义好脚本在配置文件中虚拟实例中调用脚本即可。

! Configuration File for keepalived

global_defs {
   notification_email {
       root@localhost
   }
   notification_email_from admin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node1.yan.com
   vrrp_mcast_group 224.18.0.100
}

vrrp_instance VI_1 {
    state BACKUP
    interface eno16777736
    virtual_router_id 51
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 0dc5e628
    }
    virtual_ipaddress {
        10.5.100.88/24 
    }
    notify_master "/etc/keepalived/notify.sh master" 
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault  "/etc/keepalived/notify.sh fault"
}

测试：当我们正常启动keepalived功能时，主从节点都会相应发送邮件。

[root@node1 keepalived]# mail    现在表示node1有可能成为备份节点，因为node1优先级低
Heirloom Mail version 12.5 7/5/10.  Type ? for help.
"/var/spool/mail/root": 44 messages 8 new 37 unread
 U 30 root                  Wed Jan  8 00:47  19/694   "node1 to be master: 10.5.100.88 floating"
 U 31 root                  Wed Jan  8 00:50  19/694   "node1 to be backup: 10.5.100.88 floating"
 U 32 root                  Wed Jan  8 00:50  19/694   "node1 to be master: 10.5.100.88 floating"
 U 33 root                  Wed Jan  8 00:52  19/694   "node1 to be backup: 10.5.100.88 floating"
 U 34 root                  Wed Jan  8 00:52  19/694   "node1 to be master: 10.5.100.88 floating"
   35 root                  Wed Jan  8 01:04  19/695   "node1 to be backup: 10.5.100.88 floating"
   36 root                  Wed Jan  8 01:04  19/695   "node1 to be master: 10.5.100.88 floating"
>N 37 root                  Wed Jan  8 01:08  18/684   "node1 to be backup: 10.5.100.88 floating"
 N 38 root                  Wed Jan  8 01:08  18/684   "node1 to be master: 10.5.100.88 floating"
 N 39 root                  Wed Jan  8 01:09  18/684   "node1 to be backup: 10.5.100.88 floating"
 N 40 root                  Wed Jan  8 01:09  18/684   "node1 to be master: 10.5.100.88 floating"
 N 41 root                  Wed Jan  8 01:11  18/684   "node1 to be backup: 10.5.100.88 floating"
 N 42 root                  Wed Jan  8 01:11  18/684   "node1 to be master: 10.5.100.88 floating"
 N 43 root                  Wed Jan  8 01:12  18/684   "node1 to be backup: 10.5.100.88 floating"
 N 44 root                  Wed Jan  8 01:12  18/684   "node1 to be master: 10.5.100.88 floating"
& 37
Message 37:
From root@node1.localdomain  Wed Jan  8 01:08:45 2020
Return-Path: <root@node1.localdomain>
X-Original-To: root@localhost
Delivered-To: root@localhost.localdomain
Date: Wed, 08 Jan 2020 01:08:45 -0800
To: root@localhost.localdomain
Subject: node1 to be backup: 10.5.100.88 floating
User-Agent: Heirloom mailx 12.5 7/5/10
Content-Type: text/plain; charset=us-ascii
From: root@node1.localdomain (root)
Status: R

2020-01-08 01:08:45: vrrp transition, node1 change to be backup

NODE3与NODE1同理即可。

[root@node3 ~]# vim /etc/keepalived/notify.sh 
#!/bin/bash
vip=10.5.100.88
contact='root@localhost'
 
notify() {
      mailsubject="`hostname` to be $1: $vip floating"
      mailbody="`date '+%F %H:%M:%S'`: vrrp transition, `hostname` change to be $1"
      echo $mailbody | mail -s "$mailsubject" $contact
}
 
case "$1" in
      master)
        notify master
        exit 0
        ;;
      backup)
        notify backup
        exit 0
        ;;
      fault)
        notify fault
        exit 0
        ;;
         *)
        echo 'usage:`basename $0` {master|backup|fault}'
        exit 1
        ;;
esac

定义好脚本在虚拟实例中调用：

! Configuration File for keepalived
 
global_defs {
   notification_email {
       root@localhost
   }
   notification_email_from admin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node3.yan.com
   vrrp_mcast_group 224.18.0.10
}
 
vrrp_instance VI_1 {
    state MASTER
    interface enp4s0
    virtual_router_id 77   
    priority 200
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 0dc5e628
    }
    virtual_ipaddress {
        10.5.100.88/24 
    }
    
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault  "/etc/keepalived/notify.sh fault"
}

[root@node3 ~]# mail
Heirloom Mail version 12.5 7/5/10.  Type ? for help.
"/var/spool/mail/root": 10 messages 4 new 9 unread
 U  1 root                  Mon Jan  6 18:37  23/858   "node3 to be master: 10.5.100.88 floating"
 U  2 root                  Mon Jan  6 18:41  23/858   "node3 to be master: 10.5.100.88 floating"
 U  3 root                  Mon Jan  6 18:46  23/858   "node3 to be master: 10.5.100.88 floating"
    4 root                  Wed Jan  8 17:48  23/859   "node3 to be master: 10.5.100.88 floating"
 U  5 root                  Wed Jan  8 17:51  23/858   "node3 to be master: 10.5.100.88 floating"
 U  6 root                  Wed Jan  8 18:04  23/858   "node3 to be master: 10.5.100.88 floating"
>N  7 root                  Wed Jan  8 18:10  22/848   "node3 to be master: 10.5.100.88 floating"
 N  8 root                  Wed Jan  8 18:12  22/848   "node3 to be backup: 10.5.100.88 floating"
 N  9 root                  Wed Jan  8 18:12  22/848   "node3 to be master: 10.5.100.88 floating"
 N 10 root                  Wed Jan  8 18:13  22/848   "node3 to be master: 10.5.100.88 floating"
& 7
Message  7:
From root@node3.localdomain  Wed Jan  8 18:10:05 2020
Return-Path: <root@node3.localdomain>
X-Original-To: root@node3
Delivered-To: root@node3.localdomain
From: root <root@node3.localdomain>
Date: Wed, 08 Jan 2020 18:09:04 +0900
To: root@node3.localdomain
Subject: node3 to be master: 10.5.100.88 floating
User-Agent: Heirloom mailx 12.5 7/5/10
Content-Type: text/plain; charset=us-ascii
Status: R

2020-01-08 18:09:04: vrrp transition, node3 change to be master

总结：到这里定义脚本完成了，总结一下keepalived高可用：keepalive利用虚拟vip地址使得地址可以游离，
一个虚拟实列可以对应多个地址，一般都对应一个地址，住备节点配置要一模一样，除了“主机名和网卡设备不同”，keepalived的配置文件中我们可以定义脚本，使得我们不用关闭keepalived就能实现地址游离，也可以调用外部脚本，当我们的主节点或备节点发生状态切换时，可以发送邮件告知我们。这就是简简单单的基本keepalived高可用实现。下次见。

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