Configuring A High Availability Clusterinf On CentOS
This guide shows how to set up a two nodes, High-availability HTTP cluster with heartbeat on CentOS/RHEL. Both nodes use the Apache web server to serve the same content.
Assign hostname node01 to primary node with IP address 192.168.0.20 to eth0.
Assign hostname node02 to slave node with IP address 192.168.0.21.
must return node01.
must return node02.
192.168.0.22 is the virtual IP address that will be used for our Apache webserver
(i.e., Apache will listen on that address).
1. Download and install the heartbeat package. In our case we are using CentOS/RHEL so we will install heartbeat with yum command:
#yum install heartbeat
or download these packages:
2. Now we have to configure heartbeat on our two node cluster. We will deal with three files. These three files are:
3. Now moving to our configuration files . But there is one more thing to do, that is to copy these files to the /etc/ha.d directory. In our case we copy these files as given below:
#cp /usr/share/doc/heartbeat-2.1.2/authkeys /etc/ha.d/
#cp /usr/share/doc/heartbeat-2.1.2/ha.cf /etc/ha.d/
#cp /usr/share/doc/heartbeat-2.1.2/haresources /etc/ha.d/
4. Now let’s start configuring heartbeat. First we will deal with the authkeys file, we will use authentication method 2 (sha1). For this we will make changes in the authkeysfile as below.
Then add the following lines:
2 sha1 test-ha
Change the permission of the authkeys file:
#chmod 600 /etc/ha.d/authkeys
5. Moving to our second file (ha.cf) which is the most important. So edit the ha.cf file with vi:
Add the following lines in the ha.cf file:
Note: node01 and node02 is the output generated by
6. The final piece of work in our configuration is to edit the haresources file. This file contains the information about resources which we want to highly enable. In our case we want the webserver (httpd) highly available:
Add the following line:
node01 192.168.0.22 httpd
7. Copy the /etc/ha.d/ directory from node01 to node02:
#scp -r /etc/ha.d/ root@node02:/etc/
8. As we want httpd highly enabled let’s start configuring httpd:
Add this line in httpd.conf:
9. Copy the /etc/httpd/conf/httpd.conf file to node02:
#scp /etc/httpd/conf/httpd.conf root@node02:/etc/httpd/conf/
10. Create the file index.html on both nodes (node01 & node02):
#echo “node01 heartbeat test server” > /var/www/html/index.html
#echo “node02 heartbeat test server” > /var/www/html/index.html
11. Now start heartbeat on the primary node01 and slave node02:
12. Open web-browser and type in the URL:
It will show node01 apache test server.
13. Now stop the hearbeat daemon on node01:
In your browser type in the URL http://192.168.0.22 and press enter.
It will show node02 apache test server.
14. We don’t need to create a virtual network interface and assign an IP address (192.168.0.22) to it. Heartbeat will do this for you, and start the service (httpd) itself. So don’t worry about this.
Don’t use the IP addresses 192.168.0.20 and 192.168.0.21 for services. These addresses are used by heartbeat for communication between node01 and node02. When any of them will be used for services/resources, it will disturb hearbeat and will not work. Be carefull!!!