利用Keepalvied实现负载均衡和和高可用性

1.在lvs的master节点上设置：
[root@vm1 ~]# yum install keepalived -y
[root@vm1 ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
notification_email {
[e-mail]
}
notification_email_from [e-mail]
smtp_server 127.0.0.1
# smtp_connect_timeout 30
router_id LVS_DEVEL
}

#written by :netseek
# VIP1
vrrp_instance VI_1 {
state MASTER             #备份服务器上将MASTER改为BACKUP
interface eth0
virtual_router_id 51
priority 100    # 备份服务上将100改为99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.188
#(如果有多个VIP，继续换行填写.)
}
}

virtual_server 192.168.1.188 80 {
delay_loop 6                  #(每隔10秒查询realserver状态)
lb_algo wrr                  #(lvs 算法)
lb_kind DR                  #(Direct Route)
persistence_timeout 60        #(同一IP的连接60秒内被分配到同一台realserver)
protocol TCP                #(用TCP协议检查realserver状态)

real_server 192.168.1.121 80 {
weight 3               #(权重)
TCP_CHECK {
connect_timeout 10       #(10秒无响应超时)
nb_get_retry 3
        delay_before_retry 3
        connect_port 80
        }
    }
    real_server 192.168.1.122 80 {
        weight 3
        TCP_CHECK {
        connect_timeout 10
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
        }
     }
}

[root@vm1 ~]# /etc/init.d/keepalived start

2.在lvs的backup节点上设置：
[root@vm4 ~]# yum install keepalived -y
[root@vm4 ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

 global_defs {
    notification_email {
          [e-mail]
    }
    notification_email_from [e-mail]
    smtp_server 127.0.0.1
   # smtp_connect_timeout 30
    router_id LVS_DEVEL
 }

 #written by :netseek
 # VIP1
 vrrp_instance VI_1 {
     state BACKUP             #备份服务器上将MASTER改为BACKUP
     interface eth0
     virtual_router_id 51
     priority 99    # 备份服务上将100改为99
     advert_int 1
     authentication {
         auth_type PASS
         auth_pass 1111
     }
     virtual_ipaddress {
         192.168.1.188
         #(如果有多个VIP，继续换行填写.)
     }
 }

 virtual_server 192.168.1.188 80 {
     delay_loop 6                  #(每隔10秒查询realserver状态)
     lb_algo wrr                  #(lvs 算法)
     lb_kind DR                  #(Direct Route)
     persistence_timeout 60        #(同一IP的连接60秒内被分配到同一台realserver)
     protocol TCP                #(用TCP协议检查realserver状态)

     real_server 192.168.1.121 80 {
         weight 3               #(权重)
         TCP_CHECK {
         connect_timeout 10       #(10秒无响应超时)
         nb_get_retry 3
         delay_before_retry 3
         connect_port 80
         }
     }
     real_server 192.168.1.122 80 {
         weight 3
         TCP_CHECK {
         connect_timeout 10
         nb_get_retry 3
         delay_before_retry 3
         connect_port 80
         }
      }
 }

下面我们做个测试：
配置完成后我们停掉master上的keepalived服务然后去查看日志文件，看看backup节点是否接管服务：
[root@vm1 ~]# /etc/init.d/keepalived stop
Stopping keepalived:                                       [  OK  ]
[root@vm1 ~]# tail -f /var/log/messages
Apr 20 07:05:43 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) Transition to MASTER STATE
Apr 20 07:05:44 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) Entering MASTER STATE
Apr 20 07:05:44 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) setting protocol VIPs.
Apr 20 07:05:44 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.188
Apr 20 07:05:49 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.188
Apr 20 07:08:10 vm1 Keepalived[1160]: Stopping Keepalived v1.2.7 (09/26,2012)
Apr 20 07:08:10 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) sending 0 priority
Apr 20 07:08:10 vm1 Keepalived_vrrp[1163]: VRRP_Instance(VI_1) removing protocol VIPs.
Apr 20 07:08:10 vm1 Keepalived_healthcheckers[1162]: Netlink reflector reports IP 192.168.1.188 removed
Apr 20 07:08:10 vm1 kernel: IPVS: __ip_vs_del_service: enter
我们可以看到keepalived健康检查已经被移除。
再来看看backup的日志文件：
[root@vm4 ~]# tail -f /var/log/messages
Apr 20 07:05:58 vm4 Keepalived_healthcheckers[1180]: IPVS: Destination already exists
Apr 20 07:05:58 vm4 Keepalived_healthcheckers[1180]: IPVS: Destination already exists
Apr 20 07:05:58 vm4 Keepalived_healthcheckers[1180]: Using LinkWatch kernel netlink reflector...
Apr 20 07:05:58 vm4 Keepalived_healthcheckers[1180]: Activating healthchecker for service [192.168.1.121]:80
Apr 20 07:05:58 vm4 Keepalived_healthcheckers[1180]: Activating healthchecker for service [192.168.1.122]:80
Apr 20 07:08:10 vm4 Keepalived_vrrp[1181]: VRRP_Instance(VI_1) Transition to MASTER STATE
Apr 20 07:08:11 vm4 Keepalived_vrrp[1181]: VRRP_Instance(VI_1) Entering MASTER STATE
Apr 20 07:08:11 vm4 Keepalived_vrrp[1181]: VRRP_Instance(VI_1) setting protocol VIPs.
Apr 20 07:08:11 vm4 Keepalived_vrrp[1181]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.188
Apr 20 07:08:16 vm4 Keepalived_vrrp[1181]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.188
之前backup节点一直在监视master的keepalived服务的状态，当master节点上健康检查出现故障的时候，backup自动接管服务。