Keepalived单网络主备单主配置模式(实战)

前言:

以下阐述在Keepalived中配置最简单的主备模式,后面我将一直讲述从简单的单网络单主主备模式,到双网络双主双同步的故障漂移模式。

关于Keepalived介绍,这里就不再叙述,可参阅前文:

keepalived 源代码编译安装及配置文件讲解》。

架构示意图:

多播IP是:224.0.0.111。
NAT网络可根据自己的实际情况配置。

                        +------+
			|Client|
			+------+
                           /\
		       +--------+
                       |Internet|
		       +--------+
                           /\
		       +--------+
                       |NAT 网络|
		       +--------+
                           /\
		+-----------------------+
                | 公网VIP1:172.16.8.100 |
		+-----------------------+
                   /                \
+-----------------------+      +-----------------------+
| KA+Lvs/Nginx/HAProxy  |      | KA+Lvs/Nginx/HAProxy  |
| VIP1:Master    (eth1) |多播IP| VIP1:BACKUP    (eth1) |
| IP1:172.16.8.10(eth1) |      | IP1:172.16.8.11(eth1) |
+-----------------------+      +-----------------------+
                   \                /
                +-----------------------+
                | 公网VIP1:172.16.8.100 |
		+-----------------------+
		           \/
		        +------+
			|资源池|
			+------+

环境:

MASTER:172.16.8.10
BACKUP:172.16.8.11
VIP:172.16.8.100
OS:CentOS Linux release 7.4.1708 (Core)

先决条件:

  • 时间同步。
  • 设置SELinux和防火墙。
  • 互相之间/etc/hosts文件添加对方主机名(可选)。
  • 确认接口支持多播(组播)新网卡默认支持。

keepalived 源代码编译安装及配置文件讲解》文中已完成以上必备条件。

1.单网络主备配置文件

MASTER 配置文件:

global_defs {
   notification_email {
     root@localhost
   }
   notification_email_from ka@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id ka67
   vrrp_mcast_group4 224.0.0.111
}
vrrp_instance VG_1 {
    state MASTER
    interface eth0
    virtual_router_id 103
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass renwole0
    }
    virtual_ipaddress {
        172.16.8.100
    }
    notify_master "/usr/local/keepalived/etc/keepalived/notify.sh master"
    notify_backup "/usr/local/keepalived/etc/keepalived/notify.sh backup"
    notify_fault "/usr/local/keepalived/etc/keepalived/notify.sh fault"          
}

BACKUP 配置文件:

global_defs {
   notification_email {
     root@localhost
   }
   notification_email_from ka68@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id ka68
   vrrp_mcast_group4 224.0.0.111
}
vrrp_instance VG_1 {
    state BACKUP
    interface eth0
    virtual_router_id 103
    priority 95
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass renwole0
    }
    virtual_ipaddress {
        172.16.8.100
    }
    notify_master "/usr/local/keepalived/etc/keepalived/notify.sh master"
    notify_backup "/usr/local/keepalived/etc/keepalived/notify.sh backup"
    notify_fault "/usr/local/keepalived/etc/keepalived/notify.sh fault"             
}

2.通用脚本

以下内容是notfiy.sh通用检测脚本:

$ cat /usr/local/keepalived/etc/keepalived/notify.sh
#!/bin/bash
contact='root@localhost'
                
notify() {
    local mailsubject="$(hostname) to be $1, vip floating"
    local mailbody="$(date +'%F %T'): vrrp transition, $(hostname) changed to be $1"
    echo "$mailbody" | mail -s "$mailsubject" $contact
}
                
case $1 in
master)
    notify master   
    ;;
backup)
    notify backup   
    ;;
fault)
    notify fault    
    ;;
*)
    echo "Usage: $(basename $0) {master|backup|fault}"
    exit 1
    ;;
esac

3.主备测试

测试MASTER

启动keepalived之前,查看网卡信息:

[root@ka67 keepalived]# ip a
...
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
   link/ether 00:15:5d:ae:02:78 brd ff:ff:ff:ff:ff:ff
   inet 172.16.8.10/24 brd 172.16.8.255 scope global eth0
      valid_lft forever preferred_lft forever
   inet6 fe80::436e:b837:43b:797c/64 scope link
      valid_lft forever preferred_lft forever

启动keepalived后,再次查看网卡信息:

[root@ka67 keepalived]# ip a
...
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
   link/ether 00:15:5d:ae:02:78 brd ff:ff:ff:ff:ff:ff
   inet 172.16.8.10/24 brd 172.16.8.255 scope global eth0
      valid_lft forever preferred_lft forever
   inet 172.16.8.100/32 scope global eth0
      valid_lft forever preferred_lft forever
   inet6 fe80::436e:b837:43b:797c/64 scope link
      valid_lft forever preferred_lft forever

已经成功添加VIP 172.16.8.100。

测试MASTER

启动keepalived:

[root@ka68 keepalived]# systemctl start keepalived

现在停止 MASTER,看会不会漂移到BACKUP:

[root@ka67 keepalived]# systemctl stop keepalived

查看BACKUP运行日志:

[root@ka68 keepalived]# cat /cat /var/log/messages
...
Keepalived_vrrp[1451]: VRRP_Instance(VG_1) Transition to MASTER STATE
Keepalived_vrrp[1451]: VRRP_Instance(VG_1) Entering MASTER STATE
Keepalived_vrrp[1451]: VRRP_Instance(VG_1) setting protocol VIPs.
Keepalived_vrrp[1451]: Sending gratuitous ARP on eth0 for 172.16.8.100
...

已经成功漂移到BACKUP 主机。

再次启动MASTER:

[root@ka67 keepalived]# systemctl start keepalived

查看BACKUP Keepalived服务状态:

[root@ka68 keepalived]# systemctl status keepalived
keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2018-03-02 22:13:14 EST; 15min ago
  Process: 1448 ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 1449 (keepalived)
   CGroup: /system.slice/keepalived.service
           ├─1449 /usr/local/keepalived/sbin/keepalived -D
           ├─1450 /usr/local/keepalived/sbin/keepalived -D
           └─1451 /usr/local/keepalived/sbin/keepalived -D

Keepalived_vrrp[1451]: Sending gratuitous ARP on eth0 for 172.16.8.100
Keepalived_vrrp[1451]: VRRP_Instance(VG_1) Sending/queueing gratuitous ARPs on eth0 for 172.16.8.100
Keepalived_vrrp[1451]: Sending gratuitous ARP on eth0 for 172.16.8.100
Keepalived_vrrp[1451]: Sending gratuitous ARP on eth0 for 172.16.8.100
Keepalived_vrrp[1451]: Sending gratuitous ARP on eth0 for 172.16.8.100
Keepalived_vrrp[1451]: Sending gratuitous ARP on eth0 for 172.16.8.100
Keepalived_vrrp[1451]: VRRP_Instance(VG_1) Entering BACKUP STATE
Keepalived_vrrp[1451]: VRRP_Instance(VG_1) removing protocol VIPs.
Keepalived_vrrp[1451]: Opening script file /usr/local/keepalived/etc/keepalived/notify.sh

以上状态表明,当MASTER恢复服务后,BACKUP的Keepalived会自动漂移到MASTER上。因为MASTER的权重值比BACKUP高。以上是BACKUP的漂移到MASTER的状态。