[How-To] Configure HAProxy for MariaDB Galera Cluster Load Balancing

Purpose

Explain the process of configuring the cfg file on haproxy to load balance a MariaDB Galera cluster of 3 servers.

Prerequisites

List of prerequisites:

• Root user or sudo user
• MariaDB Galera Clustered Servers (Minimum 3)
• HAProxy Server

Instructions

Step 1: Edit the HAProxy Config File

Edit the config file with:

sudo nano /etc/haproxy/haproxy.cfg

Use the following base config to either replace or edit the haproxy config on your servers to allow for load balancing of MariaDB Galera clustered servers:

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

defaults
    log     global
    option  tcplog
    timeout connect 5s
    timeout client  50s
    timeout server  50s

frontend mariadb_frontend
    bind 192.168.1.200:3306  # VIP and MariaDB port
    mode tcp
    default_backend mariadb_backend

backend mariadb_backend
    mode tcp
    balance roundrobin  # Distribute traffic evenly
    option tcp-check    # Health check for TCP (MariaDB port)
    server mariadb1 192.168.1.101:3306 check
    server mariadb2 192.168.1.102:3306 
    server mariadb3 192.168.1.103:3306

Once you update this config, you can move onto binding your VIP (Virtual IP) to your NIC.

Step 2: Bind VIP to NIC Manually

Now, we can bind the VIP you set in the config to the NIC. First, get the name of your NIC with the following command:

ip a

Look for something like ens18 or eno1. Once you know the name of your nic, use the following command to bind the VIP to the NIC:

sudo ip addr add <VIP>/32 dev <NIC_interface>

Verify the VIP is bound to the NIC with the same command:

ip a

Step 3: Make the VIP Persistent

On Debian, do this:

sudo nano /etc/network/interfaces.d/<interface>

Then, add:

auto  <interface>:0
iface <interface>:0 inet static
    address <VIP>
    netmastk 255.255.255.255

Then, restart networking:

sudo systemctl restart networking

On Ubuntu, do this:

sudo nano /etc/netplan/01-netcfg.yaml

Add an alias for the VIP under your interface configuration:

network:
  version: 2
  ethernets:
    <interface>:
      addresses:
        - <current-ip>/24
        - <VIP>/32

Then, apply netplan with the following command:

sudo netplan apply