Using keepalived to set up a virtual IP environment

using keepalived to set up a virtual IP environment Ready to

Prepare two machines with IP address information as follows:

host1:192.168.56.103
host2:192.168.56.104

For testing purposes, install Apache on two machines and start the httpd service so that the following two URLs are accessible
-http://192.168.56.103
-http://192.168.56.104 Installation keepalived

Install keepalived separately on two machines

$ sudo yum install-y keepalived

Configure keepalived keepalived configuration on host1

$ cat/etc/keepalived/keepalived.conf
vrrp_instance vi_1 {State
    MASTER
    interface eth2
    Virtual_ router_id Wuyi
    Priority
    Advert_int 1
    Authentication {
        Auth_type pass
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.56.105
    }
}

keepalived configuration on Host2

$ cat/etc/keepalived/keepalived.conf
vrrp_instance vi_1 {State
    MASTER
    interface eth2
    Virtual_ router_id Wuyi
    Priority
    Advert_int 1
    Authentication {
        Auth_type pass
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.56.105
    }
}

start the keepalived service

$ sudo service keepalived start
$ sudo chkconfig keepalived on

Test

After the service starts, access the following virtual address to access the HTTP server

http://192.168.56.105

View IP address information

IP address information on host1

$ IP Addr Show eth2
3:eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> MTU 1500 Qdisc pfifo_fast State up Qlen 1000
    Link/ether 08:00:27:32:83:82 BRD ff:ff:ff:ff:ff:ff inet 192.168.56.103/24 brd 192.168.56.255
    scope Global eth2
    inet 192.168.56.105/32 Scope Global eth2
    inet6 fe80::a00:27ff:fe32:8382/64 scope link
       valid_lft forever Preferred_lft Forever

You can see the inet 192.168.56.105/32 scope global eth2, which means that host1 is now running as master of the virtual IP.

IP address information on HOST2

$ IP Addr Show eth2
3:eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> MTU 1500 Qdisc pfifo_fast State up Qlen 1000
    Link/ether 08:00:27:ec:90:7b BRD ff:ff:ff:ff:ff:ff inet 192.168.56.104/24 brd 192.168.56.255
    scope Global eth2
    Inet6 fe80::a00:27ff:feec:907b/64 scope link
       valid_lft forever preferred_lft Forever

The IP address information on HOST2 does not contain the virtual IP "192.168.56.105" information. Verifying IP address Failover

Now manually stop the keepalived service on the host1

$ sudo service keepalived stop

IP address information on host1

$ IP Addr Show eth2
3:eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> MTU 1500 Qdisc pfifo_fast State up Qlen 1000
    Link/ether 08:00:27:32:83:82 BRD ff:ff:ff:ff:ff:ff inet 192.168.56.103/24 brd 192.168.56.255
    scope Global eth2
    Inet6 fe80::a00:27ff:fe32:8382/64 scope link
       valid_lft forever preferred_lft Forever

The IP address information on Host1 no longer contains the virtual IP "192.168.56.105" information.

IP address information on HOST2

$ IP Addr Show eth2
3:eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> MTU 1500 Qdisc pfifo_fast State up Qlen 1000
    Link/ether 08:00:27:ec:90:7b BRD ff:ff:ff:ff:ff:ff inet 192.168.56.104/24 brd 192.168.56.255
    scope Global eth2
    inet 192.168.56.105/32 Scope Global eth2
    inet6 fe80::a00:27ff:feec:907b/64 scope link
       valid_lft forever Preferred_lft Forever

You can now see that the IP address information on the HOST2 already contains the virtual IP "192.168.56.105" information.

At this point if the host1 on the Keepalived service startup, you will find that the virtual IP "192.168.56.105" and rebind to the host1.