Configuring A High Availability Cluster (Heartbeat) On CentOS

      In this example we will configure a webserver using apache and we will cluster it. It can be implemented on centos, fedora and other redhat flavors.

Pre-Configuration Requirements

1] Following are the hostnames and ipv4 addresses that will be used:

• Primary Node : IP - 192.168.1.1 Hostname - server1.linuxhome.in 
• Secondary Node : IP - 192.168.1.2 Hostname - server2.linuxhome.in 
• Virtual IP for Apache - 192.168.1.100
  

Assign virtual IP address using following steps on both node :

# cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:0

DEVICE=eth0 :0

BOOTPROTO=none

BROADCAST=192.168.1.255

HWADDR=00:15:17:a3:92:04

IPADDR=192.168.1.100

NETMASK=255.255.255.0

ONBOOT=yes

TYPE=Ethernet

2] Download and install the heartbeat package. In our case we are using CentOS so we will install heartbeat with yum:

[root@server1 ~]# yum install heartbeat

or download below package

heartbeat-2.08
heartbeat-pils-2.08
heartbeat-stonith-2.08

3] Now we have to configure heartbeat on our two node cluster. We will deal with three files. These are: (authkeys, ha.cf, haresources)

[root@server1 ~]# cp /usr/share/doc/heartbeat-2.1.2/{authkeys,ha.cf,haresources} /etc/ha.d/

4] First we will deal with the authkeys file, we will use authentication method 2 (sha1). For this we will make changes in the authkeys file as below.

[root@server1 ~]# vi /etc/ha.d/authkeys

Add the following lines at the end of file & save:

auth 2
2 sha1 test-ha

5] Also the authkeys file must be read only root:

[root@server1 ~]# chmod 600 /etc/ha.d/authkeys

6] Make changes in second file of hearteat (haresources) :

[root@server1 ~]# vi /etc/ha.d/ haresources

#Add the following line at the end of file & save:

server1.linuxhome.in  192.168.1.100  httpd

7] The final piece of work in our configuration is to edit the ha.cf file which is important :

[root@server1 ~]# vi /etc/ha.d/ha.cf

#Add / Uncommnet below lines in ha.cf file & save.

logfile /var/log/ha-log
logfacility local0
keepalive 2
deadtime 30
initdead 120
bcast eth0
udpport 694
auto_failback on
node server1.linuxhome.in
node server2.linuxhome.in

8] As we want httpd highly enabled let's start configuring httpd:

[root@server1 ~]# vi /etc/httpd/conf/httpd.conf
#Add following line:
Listen 192.168.1.100:80

9] Copy the /etc/ha.d/ directory from server1 to server2:

[root@server1 ~]# scp -rvp /etc/ha.d/ root@server2.linuxhome.in:/etc/

10] Copy httpd.conf file from server1 to server2:

[root@server1 ~]# scp -rvp /etc/httpd/conf/httpd.conf root@server2.linuxhome.in:/etc/httpd/conf/

11] Create index.html file on both server under /var/www/html directory.

On server1.linuxhome.in
[root@server1 ~]# echo "SERVER1 Apache test server" > /var/www/html/index.html

On server2.linuxhome.in
[root@server2 ~]# echo "SERVER2 Apache test server" > /var/www/html/index.html

12 ] Now start heartbeat on the primary server1 and slave server2:

# /etc/init.d/heartbeat start
13] Open web-browser and type in the URL:
http://192.168.1.100
It will show server1.linuxhome.in apache test server.
13. Now stop the hearbeat daemon on server1.linuxhome.in:
# /etc/init.d/heartbeat stop
In your browser type in the URL http://192.168.1.100 and press enter.
It will show server2.linuxhome.in apache test server.