keepalived+lvs实现双主

ゝ一纸荒年。 2022-10-06 04:49 173阅读 0赞

## keepalived+lvs实现双主 ##

lvs主备方案是当前只有一台lvs工作，这造成资源浪费，可以采用双主结构，让两台lvs当前都进行工作，采用dns轮询方式，当用户访问域名通过dns轮询每台lvs，双主结构需要两个vip，这两个vip要绑定域名。

同样，在每台lvs上安装keepalived软件，当keepalived检测到其中一个lvs宕机则将宕机的vip漂移到活动lvs上，当lvs恢复则vip又重新漂移回来。

#### 1.初始状态 ####

每台lvs绑定一个vip，共两个vip，DNS设置域名对应这两个vip，通过DNS轮询每次解析到不同的vip上即解析到不同的lvs上。

![img][]

#### 2.其中一个主机宕机 ####

其中一个主机宕机，每台lvs上安装的keepalived程序会检测到对方宕机，将宕机一方的vip漂移至活动的lvs服务器上，这样DNS轮询全部到一台lvs继续对外提供服务。

![img][img 1]

#### 3.主机恢复 ####

当主机恢复又回到初始状态，每个vip绑定在不同的lvs上。

![img][img 2]

#### 4.部署实现 ####

添加VI\_2策略。

keepalived配置，注意主备关系：

lvs01的vip1是master lvs02是backup

lvs01的vip2是backup lvs02是master

virtual\_router\_id 区分不同VIP服务，因此不能和上面一个实例一样

lvs01的keepalived配置如下：

vrrp_instance VI_2 {           	      #这里开始是VIP2的相关配置，其实和VIP1大同小异
        state BACKUP			          #VIP1的主机是VIP2的备机
        interface eth0
        virtual_router_id 52              #区分不同VIP服务，因此不能和上面一个实例一样
        priority 90                       #备机优先级设置低一点
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {		  	      #新增的VIP2
            192.168.0.110
        }
    }
    
    virtual_server 192.168.0.110 80 {     #设置VIP2的后端机器，机器是VIP1一模一样，直接拷贝就可以了
        delay_loop 6
        lb_algo rr
        lb_kind DR
        persistence_timeout 0
        protocol TCP
    
        real_server 192.168.0.200 80 {     #同样的后端
            weight 1
            TCP_CHECK {                     
                connect_timeout 1
                nb_get_retry 1
                delay_before_retry 1
                connect_port 80
            }
        }
        
        real_server 192.168.0.300 80 {     #同样的后端
            weight 1
            TCP_CHECK {                     
                connect_timeout 1  
                nb_get_retry 1
                delay_before_retry 1
                connect_port 80
            }
        }
    }

lvs02的keepalived配置如下：

vrrp_instance VI_2 { 
        state MASTER						 #第三处，VIP2此时是主机
        interface eth0
        virtual_router_id 52
        priority 100						 #第4处，主机优先级要高于备机
        advert_int 1
        authentication { 
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress { 
            192.168.0.110
        }
    }
    
    virtual_server 192.168.0.110 80 { 
        delay_loop 6
        lb_algo rr
        lb_kind DR
        persistence_timeout 0
        protocol TCP
    
        real_server 192.168.0.200 80 { 
            weight 1
            TCP_CHECK {                      
                connect_timeout 1
                nb_get_retry 1
                delay_before_retry 1
                connect_port 80
            }
        }
        
        real_server 192.168.0.300 80 { 
            weight 1
            TCP_CHECK {                      
                connect_timeout 1  
                nb_get_retry 1
                delay_before_retry 1
                connect_port 80
            }
        }
    }

启动两台LVS上的keepalived，可以查到到如下两个VIP的负载均衡配置

[root@CentOS-7-2 ~]# ipvsadm -Ln
    IP Virtual Server version 1.2.1 (size=4096)
    Prot LocalAddress:Port Scheduler Flags
      -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
    TCP  192.168.0.110:80 rr
      -> 192.168.0.200:80            Route   1      0          0         
      -> 192.168.0.300:80            Route   1      0          0         
    TCP  192.168.0.100:80 rr
      -> 192.168.0.200:80            Route   1      0          0         
      -> 192.168.0.300:80            Route   1      0          0

查看两台lvs网卡状态是否有vip

正常情况是 lvs01是192.168.0.100 ，lvs02是192.168.0.110

**配置两台RS**

[xuhongshuo@nginx01 ~]$ cat /etc/rc.d/init.d/realserver-vi2.sh 
    #!/bin/bash
        SNS_VIP=192.168.0.110
        #. /etc/rc.d/init.d/functions
        case "$1" in
        start)
            ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP
            /sbin/route add -host $SNS_VIP dev lo:0
            echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
            echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
            echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
            echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
            sysctl -p >/dev/null 2>&1
            echo "RealServer Start OK"
            ;;
        stop)
            ifconfig lo:0 down
            route del $SNS_VIP >/dev/null 2>&1
            echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
            echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
            echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
            echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
            echo "RealServer Stoped"
            ;;
        *)
            echo "Usage: $0 {start|stop}"
            exit 1
        esac
        exit 0

查看两台RS服务器的网卡状态是否已经绑定了两个vip

[xuhongshuo@nginx01 ~]$ 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
        inet 192.168.0.100/32 brd 10.100.38.201 scope global lo:0
           valid_lft forever preferred_lft forever
        inet 192.168.0.110/32 brd 10.100.38.201 scope global lo:1
           valid_lft forever preferred_lft forever
    2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
        link/ether fe:fc:fe:2d:80:ba brd ff:ff:ff:ff:ff:ff
        inet 10.100.38.14/24 brd 10.100.38.255 scope global noprefixroute eth0
           valid_lft forever preferred_lft forever

### 5.测试 ###

首先确保两个VIP都能正常工作

[root@CentOS-7-4 ~]# curl http://192.168.0.100/
    This is 192.168.0.300
    [root@CentOS-7-4 ~]# curl http://192.168.0.100/
    This is 192.168.0.200
    [root@CentOS-7-4 ~]# curl http://192.168.0.100/
    This is 192.168.0.300
    [root@CentOS-7-4 ~]# curl http://192.168.0.100/
    This is 192.168.0.200
    [root@CentOS-7-4 ~]# curl http://192.168.0.110/
    This is 192.168.0.200
    [root@CentOS-7-4 ~]# curl http://192.168.0.110/
    This is 192.168.0.300
    [root@CentOS-7-4 ~]# curl http://192.168.0.110/
    This is 192.168.0.200
    [root@CentOS-7-4 ~]# curl http://192.168.0.110/
    This is 192.168.0.300

然后停掉VIP2上LVS的keepalived服务，再次测试，服务依然正常，不过所有流量都发往VIP1。

此时，VIP1机器上能查看到两个VIP

[root@CentOS-7-2 ~]# ip a show eth0
    2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
        link/ether 00:0c:29:2e:74:89 brd ff:ff:ff:ff:ff:ff
        inet 192.168.0.140/24 brd 192.168.0.255 scope global eth0
           valid_lft forever preferred_lft forever
        inet 192.168.0.100/32 scope global eth0
           valid_lft forever preferred_lft forever
        inet 192.168.0.110/32 scope global eth0
           valid_lft forever preferred_lft forever
        inet6 fe80::20c:29ff:fe2e:7489/64 scope link 
           valid_lft forever preferred_lft forever

另一台LVS的IP漂移过来

[img]: /images/20221005/1e4e1472155d41f3a1df47527cedece8.png
[img 1]: /images/20221005/088e05f724a54803943d92d599d5a893.png
[img 2]: /images/20221005/18bb35b9ad9c424fb1f619d9e8296a57.png