数据流架构图：

一、测试环境

二、安装配置lvs、keepalived

1.分别在lvs01,lvs02主机上安装ipvsadm keepalived

    yum install ipvsadm keepalived -y

    Installed:

      ipvsadm.x86_64 0:1.27-7.el7          keepalived.x86_64 0:1.2.13-9.el7_3

2.lvs01上的keepalived配置文件，按以下内容进行修改，将lvs01配置为MASTER节点，并设置LVS的负载均衡模式为DR模式

lvs01 ~]# vi /etc/keepalived/keepalived.conf

! Configuration Filefor keepalived

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_fromAlexandre.Cassen@firewall.loc

   smtp_server 192.168.137.150

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_instance VI_1 {

    state MASTER #MASTER

    interface ens33

    virtual_router_id 52

    priority 100 #必须比BACKUP的值大

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.137.80 #VIP

    }

}

virtual_server 192.168.137.80 80 {

    delay_loop 6

    lb_algo rr #轮询算法

    lb_kind DR #DR模式

    #persistence_timeout 50

    protocol TCP

    real_server 192.168.137.128 80 {

        weight 1

            TCP_CHECK {

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

    real_server 192.168.137.134 80 {

        weight 1

            TCP_CHECK {

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

}

3、修改lvs02上的keepalived配置文件，按以下内容进行修改，其实只有2处地方与主节点的配置文件不同，即state 要修改为Backup，priority数值要比master的小
lvs02 ~]# vi /etc/keepalived/keepalived.conf

! Configuration Filefor keepalived

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_fromAlexandre.Cassen@firewall.loc

   smtp_server 192.168.137.130

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_instance VI_1 {

    state BACKUP #BACKUP

    interface eth0

    virtual_router_id 52

    priority 90 #必须比MASTER的值小

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.137.80 #VIP

    }

}

virtual_server 192.168.137.80 80 {

    delay_loop 6

    lb_algo rr #轮询算法

    lb_kind DR #DR模式

    #persistence_timeout 50

    protocol TCP

    real_server 192.168.137.128 80 {

        weight 1

            TCP_CHECK {

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

    real_server 192.168.137.134 80 {

        weight 1

            TCP_CHECK {

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

}

4.lvs01和lvs02主机上上设置keepalived开机自动启动，并启动keepalived服务

lvs01 ~]# systemctl enable keepalived

Created symlink from /etc/systemd/system/multi-user.target.wants/keepalived.service to /usr/lib/systemd/system/keepalived.service.

lvs01 ~]# systemctl start keepalived

注：查看日志是否有相关日志文件/var/log/messages输出

systemd: Started LVS and VRRP High Availability Monitor.

Keepalived_vrrp[2416]:VRRP_Instance(VI_1) Transition to MATER STATE

Keepalived_healthcheckers[2415]: Netlink reflector reports IP 192.168.137.80 added.

Jun 12 17:07:26 server2 Keepalived_vrrp[15654]: VRRP_Instance(VI_1) Entering BACKUP STATE

5.查看vip是否已经绑定到网卡，

lvs01 ~]# ip a

inet 192.168.137.150/24 brd 192.168.137.255 scope global ens33

       valid_lft forever preferred_lft forever

inet 192.168.137.80/32 scope global ens33

       valid_lft forever preferred_lft forever

lvs02 ~]# ip a          ##介意可以看到vip不在lvs02上

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:a5:b4:85 brd ff:ff:ff:ff:ff:ff

    inet 192.168.137.130/24 brd 192.168.137.255 scope global eth0

    inet6 fe80::20c:29ff:fea5:b485/64 scope link 

       valid_lft forever preferred_lft forever

6.查看LVS的状态，可以看到VIP和两台Realserver的相关信息

lvs01 ~]# ipvsadm -L -n

IP Virtual Server version 1.2.1 (size=4096)

Prot LocalAddress:Port Scheduler Flags

  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

TCP  192.168.137.80:80 rr

  -> 192.168.137.128:80           Route   1      0          0         

  -> 192.168.137.134:80           Route   1      0          0

7.由于DR模式是后端两台realserver在响应请求时直接将数据包发给客户端，无需再经过LVS，这样减轻了LVS的负担、提高了效率，但由于LVS分发给realserver的数据包的目的地址是VIP地址，因此必须把VIP地址绑定到realserver的回环网卡lo上，否则realserver会认为该数据包不是发给自己因此会丢弃不作响应。另外由于网络接口都会进行ARP广播响应，因此当其他机器也有VIP地址时会发生冲突，故需要把realserver的lo接口的ARP响应关闭掉。我们可以用以下脚本来实现VIP绑定到lo接口和关闭ARP响应。

web01 ~]# vim /etc/init.d/lvsrs.sh

#!/bin/bash

#chkconfig: 2345 80 90

vip=192.168.137.80

ifconfig lo:0 $vip broadcast $vip netmask 255.255.255.255 up

route add -host $vip 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

执行该脚本设置该脚本开机自动执行，查看IP地址，发现lo接口已经绑定了VIP地址

@web01 ~]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

    inet 192.168.137.80/32 brd 192.168.137.80 scope global lo:0

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

@web02 ~]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

    inet 192.168.137.80/32 brd 192.168.137.80 scope global lo:0

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

三、LVS负载均衡测试

3、查看LVS的状态，可以看到两台realserver各有2个不活动的连接，说明按1：1权重的轮询也有生效，不活动连接是因为我们只是访问一个静态页面，访问过后很快就会处于不活动状态

lvs01 ~]# ipvsadm -L -n

IP Virtual Server version 1.2.1 (size=4096)

Prot LocalAddress:Port Scheduler Flags

  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

TCP  192.168.137.80:80 rr

  -> 192.168.137.128:80           Route   1      0          2         

  -> 192.168.137.134:80           Route   1      0          2 

四、Keepalived高可用测试

1、停止lvs01上的keepalived服务，再观察它的日志，可以发现其绑定的VIP被移除，两个realserver节点也被移除了

lvs01 ~]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1

    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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:77:71:4e brd ff:ff:ff:ff:ff:ff

    inet 192.168.137.150/24 brd 192.168.137.255 scope global ens33

       valid_lft forever preferred_lft forever

    inet6 fe80::1565:761b:d9a2:42e4/64 scope link 

       valid_lft forever preferred_lft forever

lvs01 ~]# ipvsadm -L -n

IP Virtual Server version 1.2.1 (size=4096)

Prot LocalAddress:Port Scheduler Flags

  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

此时发现vip及rs节点出现在lvs02上：并且用vip可还可正常访问，表示漂移成功，并且如果之后lvs01恢复正常，vip依然会漂到lvs01上，原因为keepalived的配置文件里状态为master,

lvs02 ~]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:a5:b4:85 brd ff:ff:ff:ff:ff:ff

    inet 192.168.137.130/24 brd 192.168.137.255 scope global eth0

    inet 192.168.137.80/32 scope global eth0

    inet6 fe80::20c:29ff:fea5:b485/64 scope link 

       valid_lft forever preferred_lft forever

[root@lvs02 ~]# ipvsadm -L -n

IP Virtual Server version 1.2.1 (size=4096)

Prot LocalAddress:Port Scheduler Flags

  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

TCP  192.168.137.80:80 rr

  -> 192.168.137.128:80           Route   1      0          0         

  -> 192.168.137.134:80           Route   1      0          0 

2.我们将web01的httpd服务停止，模拟web01出现故障不能提供web服务，测试keepalived能否及时监控到并将web01从LVS中剔除，不再分发请求给web01，防止用户访问到故障的web服务器

@web01 ~]# /usr/local/apache24/bin/httpd -k stop

@lvs02 ~]# ipvsadm -L -n

IP Virtual Server version 1.2.1 (size=4096)

Prot LocalAddress:Port Scheduler Flags

  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

TCP  192.168.137.80:80 rr

  -> 192.168.137.134:80           Route   1      0          0         

@lvs02 ~]#

此时把web01的http服务启动，keepalive的进程会检测到rs恢复，自动添加到rs池中。

本文出自 “Gavin” 博客，请务必保留此出处http://guopeng7216.blog.51cto.com/9377374/1934678

keepalived+LVS实现高可用的Web负载均衡