How to Install and Configure HAProxy on Rocky Linux 8

Prerequisites

A server running RockyLinux 8.
A root password is configured on the server.

Install HAProxy

By default, the HAProxy package is available in the Rocky Linux 8 default repo. You can install it with the following command:

dnf install haproxy -y

Once the HAProxy is installed, start the HAProxy service and enable it to start at system reboot:

systemctl start haproxy
systemctl enable haproxy

Configure HAProxy

Next, you will need to edit /etc/haproxy/haproxy.cfg file and modify two sections frontend and backend. In the Frontend section, you will need to define HAProxy IP its port, stats URI and backend name. In the Backend section, you will need to define the load balance algorithm, backend server’s name, IPs, and port.

nano /etc/haproxy/haproxy.cfg

Modify the following sections:

frontend http_balancer
    bind 172.16.10.10:80
    option http-server-close
    option forwardfor
    stats uri /haproxy?stats

default_backend     Apache_webservers

backend apache_webservers
    mode        http
    balance     roundrobin
    option httpchk HEAD / HTTP/1.1\r\nHost:\ localhost    
    server  apache1  172.16.10.11:80  check
    server  apache2  172.16.10.12:80  check

Save and close the file when you are finished then you will need to edit /etc/rsyslog.conf file.

nano /etc/rsyslog.conf

Uncomment the following lines:

module(load="imudp")
input(type="imudp" port="514")

Save and close the file then create haproxy.conf file for rsyslog with the following command:

nano /etc/rsyslog.d/haproxy.conf

Add the following lines:

local2.=info     /var/log/haproxy-access.log
local2.notice    /var/log/haproxy-info.log

Next, start the rsyslog service and enable it to start at system reboot:

systemctl start rsyslog
systemctl enable rsyslog

Finally, restart the HAProxy service to apply the changes:

systemctl restart haproxy

You can also verify the status of the HAProxy service with the following command:

systemctl status haproxy

You should see the following output:

? haproxy.service - HAProxy Load Balancer
   Loaded: loaded (/usr/lib/systemd/system/haproxy.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2021-08-03 03:10:37 EDT; 1min 16s ago
  Process: 44032 ExecStartPre=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 44036 (haproxy)
    Tasks: 2 (limit: 12524)
   Memory: 3.1M
   CGroup: /system.slice/haproxy.service
           ??44036 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid
           ??44111 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid

Aug 03 03:10:36 RockyLinux8 systemd[1]: Starting HAProxy Load Balancer...
Aug 03 03:10:37 RockyLinux8 systemd[1]: Started HAProxy Load Balancer.

Configure Firewall

Next, you will need to configure firewalld on all servers and allow port 80 through the firewall.

You can run the following command to allow port 80:

firewall-cmd --permanent --add-port=80/tcp

Next, reload the firewalld service to apply the changes.

firewall-cmd --reload

Configure Backend Servers

Next, you will need to install the Apache server on both backend servers. Run the following command to install the Apache server.

dnf install httpd -y

Once Apache server has been installed, start the Apache service and enable it to start at system reboot:

systemctl start httpd
systemctl enable httpd

Next, you will need to modify the default index.html file on both backend servers.

On the first backend, edit the index.html file with the following command:

nano /usr/share/httpd/noindex/index.html

Remove all lines and add the following line:

Welcome to First Apache Web Server!

Save and close the file when you are finished.

On the second backend, edit the index.html file with the following command:

nano /usr/share/httpd/noindex/index.html

Remove all lines and add the following line:

Welcome to Second Apache Web Server!

Save and close the file when you are finished.

Verify HAProxy

At this point, HAProxy is configured to forward all incoming requests to the backend servers based on the load-balancing algorithm. Now, it's time to check whether HAProxy is working properly or not.

Open your web browser and type the HAProxy IP in the URL http://172.16.10.10. You should see your first apache webserver page:

Next, refresh the same page again, you should see your second apache webserver page:

This confirms that HAProxy is working as expected and it is distributing traffic between two backend servers.

Conclusion

Congratulations! you have successfully installed and configured the HAProxy load balancer on Rocky Linux 8. You can now implement HAProxy in the production environment to achieve high performance and scalability.

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