Using HAProxy with multiple ports on front- and backend

HAProxy is an awesome tool. It helps distribute traffic across multiple servers. But what if you need multiple ports on both frontend and backend? Don’t worry! It’s easier than you think.

Why Use Multiple Ports?

Sometimes, one port isn’t enough. Maybe you have different services running on different ports. Or you need to serve both HTTP and HTTPS. HAProxy can handle it all!

Setting Up the Frontend

The frontend is where HAProxy listens for incoming connections. You can configure it to listen on multiple ports.

Here’s a simple example:

frontend my_frontend
    bind *:80
    bind *:443
    mode http
    default_backend my_backend

This makes HAProxy listen on both port 80 (HTTP) and 443 (HTTPS).

Adding More Frontend Rules

You might need to route different ports to different backends. No problem! Just add ACLs.

frontend multi_port_frontend
    bind *:8080
    bind *:8443
    mode http

    acl is_api path_beg /api
    use_backend api_backend if is_api
    default_backend web_backend

Now, requests going to /api are sent to api_backend, while everything else goes to web_backend.

Setting Up the Backend

Backends define which servers handle requests. Each backend can have multiple servers and ports.

Here’s how to set one up:

backend my_backend
    server server1 192.168.1.10:8080
    server server2 192.168.1.11:8081

This means:

• Requests are balanced between server1 and server2.
• Server1 listens on port 8080.
• Server2 listens on port 8081.

Mixing Multiple Ports in Backends

What if your backend services run on different ports?

Here’s how to handle that:

backend multi_service_backend
    server app1 192.168.1.20:9000
    server app2 192.168.1.21:9100

Now HAProxy knows where to send the traffic.

Handling SSL Traffic

If you’re using both HTTP and HTTPS, you’ll want HAProxy to handle SSL connections.

Modify your frontend like this:

frontend ssl_frontend
    bind *:443 ssl crt /etc/haproxy/certs/server.pem
    mode http
    default_backend secure_backend

HAProxy now terminates SSL and forwards traffic securely.

Final Thoughts

Using HAProxy with multiple ports on frontend and backend is simple. Just:

• Define multiple bind statements in your frontend.
• Use ACLs to route traffic based on conditions.
• Point backends to servers with the correct ports.

With these steps, you can manage different services, balance load, and keep traffic flowing smoothly.

Happy load balancing!