Load balancing with HAProxy¶

The free and open source software, HAProxy, provides a high-availability load balancer and reverse proxy for TCP and HTTP-based applications. HAProxy can distribute requests across multiple servers, ensuring optimal performance and security.

Here are the benefits of using HAProxy:

HAProxy supports layer 4 (TCP) and layer 7 (HTTP) load balancing, which means it can handle different network traffic and protocols. HAProxy requires patched backends to tunnel IP traffic in layer 4 load-balancing tunnel mode. This mode also disables some layer 7 advanced features.
HAProxy has rich features, such as URL rewriting, SSL/TLS termination, gzip compression, caching, observability, health checks, retries, circuit breakers, WebSocket, HTTP/2 and HTTP/3 support, and more.
HAProxy has a reputation for being fast and efficient in terms of processor and memory usage. The software is written in C and has an event-driven and multithreaded architecture.
HAProxy has a user-friendly status page that shows detailed information about the load balancer and the backends. The software also integrates well with third-party monitoring tools and services.
HAProxy supports session retention and cookie guidance, which can help with sticky sessions and affinity.

Create a user¶

Access the server as a user with administrative privileges, either root or use sudo.

Create a Dedicated HAProxy user account for HAProxy to interact with your MySQL instance. This account enhances security.

Make the following changes to the example CREATE USER command to replace the placeholders:

Replace haproxy_user with your preferred username.
Substitute haproxy_server_ip with the actual IP address of your HAProxy server.
Choose a robust password for the ‘strong_password’.

Execute the following command:

mysql> CREATE USER 'haproxy_user'@'haproxy_server_ip' IDENTIFIED BY 'strong_password';

Grant the minimal set of privileges necessary for HAProxy to perform its health checks and monitoring.

Execute the following:

GRANT SELECT ON `mysql`.* TO 'haproxy_user'@'haproxy_server_ip';
FLUSH PRIVILEGES;

Important Considerations¶

If your MySQL servers are part of a replication cluster, create the user and grant privileges on each node to ensure consistency.

For enhanced security, consider restricting the haproxy_user to specific databases or tables to monitor rather than granting permissions to the entire mysql database schema.

Install¶

Add the HAProxy Enterprise repository to your system by following the instructions for your operating system.

Install HAProxy on the node you intend to use for load balancing. You can install it using the package manager.

On a Debian-derived distributionOn a Red Hat-derived distribution

$ sudo apt update
$ sudo apt install haproxy

$ sudo yum update
$ sudo yum install haproxy

To start HAProxy, use the haproxy command. You may pass any number of configuration parameters on the command line. To use a configuration file, add the -f option.

$ # Passing one configuration file
$ sudo haproxy -f haproxy-1.cfg

$ # Passing multiple configuration files
$ sudo haproxy -f haproxy-1.cfg haproxy-2.cfg

$ # Passing a directory
$ sudo haproxy -f conf-dir

You can pass the name of an existing configuration file or a directory. HAProxy includes all files with the .cfg extension in the supplied directory. Another way to pass multiple files is to use -f multiple times.

For more information, see HAProxy Management Guide

For information, see HAProxy configuration file

Important

In Percona XtraDB Cluster 8.0, the default authentication plugin is caching_sha2_password. HAProxy does not support this authentication plugin. Create a mysql user using the mysql_native_password authentication plugin.

mysql> CREATE USER 'haproxy_user'@'%' IDENTIFIED WITH mysql_native_password by '$3Kr$t';

Uninstall¶

To uninstall haproxy version 2 from a Linux system, follow the latest instructions.