Configure HAProxy Load Balancer with SSL on Ubuntu 18.04/Debian 10/9

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In this guide, we are going to learn how to configure HAProxy load balancer with SSL on Ubuntu 18.04/Debian 10/9. HAProxy is the de-factor opensource solution providing very fast and reliable high availability, load balancing and proxying for TCP and HTTP-based applications. As such, HAProxy is suited for very high traffic web sites.

Configure HAProxy Load Balancer with SSL on Ubuntu 18.04/Debian 10/9

In this guide, we are going to demonstrate how HAProxy performs load balancing using three web servers serving simple html pages. Our architecture looks like in the diagram below;

Configure HAProxy Load Balancer with SSL on Ubuntu 18.04/Debian 10/9

Install HAProxy on Ubuntu 18.04/Debian 10/Debian 9

Run system update.

apt update
apt upgrade

Once the update is done, proceed to install HAProxy on your Ubuntu/Debian systems.

Create HAProxy Repository

There are different HAProxy packages for each system. Hence, you need to create dedicated repository for each system.

Before you can create the repos, install the APT signing Key.

apt install curl -y
curl https://haproxy.debian.net/bernat.debian.org.gpg | apt-key add -

Next, create HAProxy repositories. On Debian 10 Buster/Debian 9 Stretch, run the command below to create the repo.

echo "deb http://haproxy.debian.net $(lsb_release -cs)-backports-2.0 main" | tee /etc/apt/sources.list.d/haproxy.list

On Ubuntu 18.04, you need to add the vbernat haproxy PPA repos as shown below;

apt install software-properties-common
add-apt-repository ppa:vbernat/haproxy-2.0

Once the repos are created on each system, perform system update and install HAProxy.

apt update
apt install haproxy=2.0.\*

To check the version of installed HAProxy, run the command below;

haproxy -v
HA-Proxy version 2.0.1-1~bpo9+1 2019/06/27 - https://haproxy.org/

Configure HAProxy Load Balancer on Ubuntu 18.04/Debian 10/9

Configuration of HAProxy is all about where it is listening for connection requests and where to forward such requests to. It is therefore made up of frontend system and one or more back-end systems. The front-end system defines the IP address and port on which the proxy listens as well as the back-end systems to use for a particular proxy.

The main configuration file for HAProxy is /etc/haproxy/haproxy.cfg.

The HAProxy configuration file is made up of four sections;

  • global
    The global section defines process-wide security and performance tunings that affect HAProxy at a low level.
  • defaults
    The global section defines the configuration settings that are applied to all of the frontend and backend sections. You can define multiple default sections but the sub-sequent defaults sections override that came before it.
  • frontend
    When HAProxy is placed as a reverse proxy, the frontend section defines the IP addresses and ports that clients can connect to.
  • backend
    The backend section defines the group of servers that will be load balanced and assigned to handle requests.

The frontend and backend sections can be combined using the listen section. It can also be used to server HAProxy statistics page.

To read more on the explanation of HAProxy configuration sections, check here.

Before we can begin any configuration, let us create a backup of the configuration file.

cp /etc/haproxy/haproxy.cfg{,.bak}

The default HAProxy configuration contain the default configuration settings for the global and default section.

global
        log /dev/log    local0
        log /dev/log    local1 notice
        chroot /var/lib/haproxy
        stats socket /run/haproxy/admin.sock mode 660 level admin expose-fd listeners
        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/
        # An alternative list with additional directives can be obtained from
        #  https://mozilla.github.io/server-side-tls/ssl-config-generator/?server=haproxy
        ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:RSA+AESGCM:RSA+AES:!aNULL:!MD5:!DSS
        ssl-default-bind-options no-sslv3
        ## Add the line below
        tune.ssl.default-dh-param 2048

defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull
        timeout connect 5000
        timeout client  50000
        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

We are going to leave this settings just the way they are and add the our configurations for the frontend and backend sections. However, you can add the line tune.ssl.default-dh-param 2048 to the global section which sets the maximum size of the Diffie-Hellman parameters used for generating the ephemeral/temporary Diffie-Hellman key in case of DHE key exchange.

Configure HAProxy with SSL on Ubuntu 18.04/Debian 10/9

As stated above, frontend section defines the IP address on which to listen for connection requests.

Since we are configuring HAProxy with SSL, you need to generate the SSL/TLS certificates. This guide uses self-signed certificates. You can get your own from a trusted CA.

Generating Self-Signed SSL Certificates for HAProxy

Begin with generating private key.

openssl genrsa -out /etc/ssl/private/haproxy.key 2048

Next, generate the Certificate signing request (CSR).

openssl req -new -key /etc/ssl/private/haproxy.key -out /etc/ssl/certs/haproxy.csr

Create the Self Signed Certificate (CRT)

openssl x509 -req -days 365 -in /etc/ssl/certs/haproxy.csr -signkey /etc/ssl/private/haproxy.key -out /etc/ssl/certs/haproxy.crt

Create SSL pem file by containing both the key and the certificate.

cat /etc/ssl/private/haproxy.key /etc/ssl/certs/haproxy.crt >> /etc/ssl/certs/haproxy.pem

Define HAProxy Frontend Configuration Settings

Open the HAProxy configuration file and configure the frontend settings as shown below;

vim /etc/haproxy/haproxy.cfg

This is our frontend configuration basic settings.

frontend lb_01
    bind 192.168.43.62:443 ssl crt /etc/ssl/certs/haproxy.pem
    default_backend webapp_backends
  • bind setting assigns a listener to a given IP address and port. ssl crt instructs HAProxy to use SSL.
  • default_backend gives the name of a backend to send traffic to.

Define HAProxy Backend Configuration Settings

In its basic configuration, out backend settings are defined below;

backend webapp_backends
    balance roundrobin
    server webapp_01.example.com  192.168.43.252:80 check
    server webapp_02.example.com  192.168.43.174:80 check
    server webapp_03.example.com  192.168.43.21:80 check
  • balance setting defines the load balancer scheduling algorithm.
    • roundrobin selects the servers in turns.
    • Other common algorithms is leastconn which enabled the load balancer to forward request to servers with least connections.
  • server setting specify the servers available in the back end.
    • check option enables health checks on the server such that if one of them is down, requests are directed to the available backend servers.

Enable HAProxy Statistics via Web

listen stats
    bind 192.168.43.62:443 ssl crt /etc/ssl/certs/haproxy.pem
    stats enable                    # enable statistics reports  
    stats hide-version              # Hide the version of HAProxy
    stats refresh 30s               # HAProxy refresh time
    stats show-node                 # Shows the hostname of the node
    stats auth admin:[email protected]       # Authentication for Stats page
    stats uri /lb_stats             # Statistics URL

Verify HAProxy Configuration

Once the configuration is done, you can run the command below to check the HAProxy configuration for any error.

haproxy -c -f /etc/haproxy/haproxy.cfg
Configuration file is valid

Running HAProxy

When installed, HAProxy is set to run by default. To restart and enable HAProxy to run on system boot;

systemctl restart haproxy
systemctl enable haproxy

To check the status;

systemctl status haproxy
● haproxy.service - HAProxy Load Balancer
   Loaded: loaded (/lib/systemd/system/haproxy.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2019-07-12 23:22:58 EAT; 5s ago
     Docs: man:haproxy(1)
           file:/usr/share/doc/haproxy/configuration.txt.gz
  Process: 10686 ExecStartPre=/usr/sbin/haproxy -f $CONFIG -c -q $EXTRAOPTS (code=exited, status=0/SUCCESS)
 Main PID: 10687 (haproxy)
    Tasks: 2 (limit: 2340)
   CGroup: /system.slice/haproxy.service
           ├─10687 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -S /run/haproxy-master.sock
           └─10688 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -S /run/haproxy-master.sock

If UFW is running, Open port 443,

ufw allow 443

Verify HAProxy Load Balancing

Now that the configuration is done, you can access your HAProxy from web to see if it performs any round-robin load balancing using the address, https://<haproxy-IP>.

The first page the loads shows content server from webapp_01. For this demo, we have three test html pages. When refreshed, content from other servers is shown.

Configure HAProxy with SSL on Ubuntu 18.04/Debian 10/9
HAProxy with SSL
HAProxy Load Balancer on Ubuntu 18.04/Debian 10 buster

Well, as you can realize, the pages are served in order, one after the other. That is it on our basic tutorial on how to configure HAProxy Load Balancer with Self-Signed certificate on Ubuntu 18.04/Debian 10/Debian 9.

You can read more about HAProxy and configuration options in the documentation page below;

HAProxy Configuration Manual

Related Tutorials

Setup HAProxy Load Balancer on Fedora 30/Fedora 29

How to Install and Configure Pound as Apache HTTP Load balancer on Ubuntu 16.04

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