How to Setup HAProxy Load Balancer on Ubuntu 18.04 & 16.04

Written by Rahul, Updated on October 22, 2019

General Articles cluster, HAProxy, linuxmint, load-balancing, Ubuntu

HAProxy is a very fast and reliable solution for high availability, load balancing, It supports TCP and HTTP-based applications. Nowadays maximizing websites up-time is very crucial for heavy traffic websites. This is not possible with single server setup. Then we need some high availability environment that can easily manage with single server failure.

This article will help you to setup HAProxy load balancing environment on Ubuntu, Debian and LinuxMint. This will configure a Layer 4 Load Balancing (Transport Layer). Which will balance load and transfer requests to different-2 servers based on IP address and port numbers.

Network Details –

Below is our network server. There are 3 web servers running with Apache2 and listening on port 80 and one HAProxy server.

Web Server Details:

Server 1:    web1.example.com     192.168.1.101
Server 2:    web2.example.com     192.168.1.102
Server 3:    web3.example.com     192.168.1.103

HAProxy Server: 

HAProxy:     haproxy              192.168.1.12

Step 1 – Install HAProxy

Now start the setup. SSH to your HAProxy server as a privileged user and install HAProxy using following commands.

sudo add-apt-repository ppa:vbernat/haproxy-1.8
sudo apt-get update
sudo apt-get install haproxy

Step 2 – Configure HAProxy Load Balancing

Now edit haproxy default configuration file /etc/haproxy/haproxy.cfg and start configuration.

sudo vi /etc/haproxy/haproxy.cfg

Default Settings:

You will find some default configuration like below. If you don’t have enough idea about this, you can keep as it is.

global
	log /dev/log	local0
	log /dev/log	local1 notice
	chroot /var/lib/haproxy
	stats socket /run/haproxy/admin.sock mode 660 level admin
	stats timeout 30s
	user haproxy
	group haproxy
	daemon

	# Default SSL material locations
	ca-base /etc/ssl/certs
	crt-base /etc/ssl/private

	# Default ciphers to use on SSL-enabled listening sockets.
	# For more information, see ciphers(1SSL). This list is from:
	#  https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
	ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256::RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
	ssl-default-bind-options no-sslv3

defaults
	log	global
	mode	http
	option	httplog
	option	dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
	errorfile 400 /etc/haproxy/errors/400.http
	errorfile 403 /etc/haproxy/errors/403.http
	errorfile 408 /etc/haproxy/errors/408.http
	errorfile 500 /etc/haproxy/errors/500.http
	errorfile 502 /etc/haproxy/errors/502.http
	errorfile 503 /etc/haproxy/errors/503.http
	errorfile 504 /etc/haproxy/errors/504.http

Adding HAProxy Listener:

Now tell HAProxy to where to listen for new connections. As per below configuration HAProxy will list on port 80 of 192.168.1.12 ip address.

frontend Local_Server
    bind 192.168.1.12:80
    mode http
    default_backend My_Web_Servers

Add Backend Web Servers:

As per above configuration haproxy is now listening on port 80. Now define the backend web servers where HAProxy send the request.

backend nodes
    mode http
    balance roundrobin
    option forwardfor
    http-request set-header X-Forwarded-Port %[dst_port]
    http-request add-header X-Forwarded-Proto https if { ssl_fc }
    option httpchk HEAD / HTTP/1.1rnHost:localhost
    server web1.example.com  192.168.1.101:80
    server web2.example.com  192.168.1.102:80
    server web3.example.com  192.168.1.103:80

Enable Stats (Optional)

Now if you want you can enable Haproxy statistics by adding following configuration in HAProxy configuration file.

listen stats *:1936
    stats enable
    stats hide-version
    stats refresh 30s
    stats show-node
    stats auth username:password
    stats uri  /stats

Step 3 – Final HAProxy Configuration File

The final configuration file may look like below:

global
	log /dev/log	local0
	log /dev/log	local1 notice
	chroot /var/lib/haproxy
	stats socket /run/haproxy/admin.sock mode 660 level admin
	stats timeout 30s
	user haproxy
	group haproxy
	daemon

	# Default SSL material locations
	ca-base /etc/ssl/certs
	crt-base /etc/ssl/private

	# Default ciphers to use on SSL-enabled listening sockets.
	# For more information, see ciphers(1SSL). This list is from:
	#  https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
	ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256::RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
	ssl-default-bind-options no-sslv3

defaults
	log	global
	mode	http
	option	httplog
	option	dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
	errorfile 400 /etc/haproxy/errors/400.http
	errorfile 403 /etc/haproxy/errors/403.http
	errorfile 408 /etc/haproxy/errors/408.http
	errorfile 500 /etc/haproxy/errors/500.http
	errorfile 502 /etc/haproxy/errors/502.http
	errorfile 503 /etc/haproxy/errors/503.http
	errorfile 504 /etc/haproxy/errors/504.http

frontend Local_Server
    bind 192.168.1.12:80
    mode http
    default_backend My_Web_Servers

backend My_Web_Servers
    mode http
    balance roundrobin
    option forwardfor
    http-request set-header X-Forwarded-Port %[dst_port]
    http-request add-header X-Forwarded-Proto https if { ssl_fc }
    option httpchk HEAD / HTTP/1.1rnHost:localhost
    server web1.example.com  192.168.1.101:80
    server web2.example.com  192.168.1.102:80
    server web3.example.com  192.168.1.103:80

listen stats *:1936
    stats enable
    stats hide-version
    stats refresh 30s
    stats show-node
    stats auth username:password
    stats uri  /stats

Step 4 – Restart HAProxy

Now you have made all necessary changes in your HAProxy server. Now verify configuration file before restarting service using the following command.

haproxy -c -f /etc/haproxy/haproxy.cfg

If above command returned output as configuration file is valid then restart HAProxy service

sudo service haproxy restart

Step 5 – Verify HAProxy Setting

At this stage, we have a full functional HAProxy setup. At each web server node, I have a demo index.html page showing servers hostname, So we can easily differentiate between servers web pages.

Now access port 80 on IP 192.168.1.12 (as configured above) in the web browser and hit refresh. You will see that HAProxy is sending requests to backend servers one by one (as per round-robin algorithm).

With each refresh you can that HAProxy is sending request one by one to a backend server.

Reference: http://www.haproxy.org/download/1.5/doc/configuration.txt

3 Comments

Fernando Tlatilolpa Reply to Fernando
October 22, 2019 at 4:52 am
Hi Rahul, when I pause server1 and server2 I thought Server3 always will be selected but it is not, it got freeze for certain time and if again goes to 1 or 2, lb waits for them instead of select 3, is it feasible to resolve this?
Thanks and regards.
Martti Innanen Reply to Martti
August 1, 2019 at 9:49 am
If you have problems starting HAproxy with the error haproxy.service: “Start request repeated too quickly”, check that you don’t have other processes running (f.e. Apache at port 80) on the HAproxy device that bind to the same ports that HAproxy does.
Robert Reply to Robert
June 20, 2019 at 10:28 am
Hi,
In the beginning you’re talking about layer 4, but your actual configuration is on http layer 7… We have trouble routing the origin IP to the backend server. we are currently using HAPROXY and KEEPALIVED and using layer 4 tcp for this. Any idea how to solve this problem, while keeping the HA and LB in place?
Greetings Robert