Creating a Load Balancer

Now, we'll start off by installing HAProxy:

[root@Server1]# yum -y install haproxy

Enable and start the service:

[root@Server1]# systemctl enable haproxy
[root@Server1]# systemctl start haproxy

Then verify that incoming port 80 traffic is permitted through the firewall. Running firewall-cmd --list-all should show http in the list of allowed services.

We need to configure the HAProxy's frontend and backend. HAProxy should listen on port 80, and use node1 and node2 as the backend nodes. Let's edit /etc/haproxy/haproxy.cfg and add the configuration code:

    timeout check            10s
    maxconn                  3000

# Our code starts here:
    
frontend app1
        bind *:80		
        mode http
        default_backend apache_nodes
    
backend apache_nodes
        mode http
        balance source		
        server node1 10.0.1.20:8080 check
        server node2 10.0.1.30:8080 check

# End of our code
#-------------------------------------------------------
# main frontend which proxys to the backends
#-------------------------------------------------------

We'll have to restart the daemon so that our changes take effect, then check with ss:

[root@Server1]# systemctl restart haproxy
[root@Server1]# ss -lntp

We need to permit incoming port 8080/TCP traffic on node1 and node2. On each node (after logging in, then becoming root), perform the following:

[root@node]# firewall-cmd --permanent --add-port=8080/tcp

Then reload the firewall configuration:

[root@node]# firewall-cmd --reload

On Client1, we can run a curl on the Server1 private IP address:

[cloud_user@Client1]$ curl &ltServer1_IP_ADDRESS>