How to configure HAProxy for WebSocket connections

WebSocket applications enable real-time two-way communication between client and server. Even though WebSocket connections are used, effective traffic management mechanisms are still required to avoid overloading the server, resulting in service interruption and unavailability.

HAProxy is a free and reliable load balancer that can also be used as a reverse proxy. By configuring HAProxy to support WebSocket connections, you can better utilize the real-time data transmission characteristics of WebSockets and reduce the server load. This article will describe the detailed steps to configure HAProxy to support WebSocket connections.

Step-by-step guide on how to configure HAProxy for WebSocket connections

Through the WebSocket connection, the communication between the server and the client is persistent until one of the parties actively closes the connection. To ensure that traffic can be evenly distributed to other servers when the server load is too high, a load balancer approach can be used. In this way, the client and server can maintain a continuous connection and enjoy a low-latency communication environment.

1. Install HAProxy

The first step in configuring HAProxy's WebSocket connection is to confirm that HAProxy is installed. If it is not installed yet, follow these steps to install it:

$sudo apt—get install haproxy

2. Edit HAProxy configuration

In order for WebSocket connections to pass through HAProxy, the HAProxy configuration needs to be adjusted to support WebSocket connections. This includes making changes to the "server" section and setting up the "frontend" and "backend" sections.

Use a text editor to open the HAProxy configuration as shown below:

$sudo nano/etc/haproxy/haproxy.cfg

In the "Delete" section, modify it as shown in the image below. First, we specify that we are using an HTTP connection and define where to send the log files. Next, we set timeouts for different activities. For example, a connection timeout is the maximum amount of time it takes to connect to a server. If the maximum time is reached, the connection is considered failed and can be retried.

For this case, we set the connection timeout to 5000 milliseconds. You can adjust the timeout based on your situation. Tweak them based on your application, keeping in mind the duration of WebSocket sessions and how long you expect them to live.

Next, we have to create the "frontend" part, where we bind the port used for the WebSocket connection and the referenced backend server. In this case, we specify port 80 and give the URL to access the “Stats” page to monitor our HAProxy. Finally, we define the backend parts that are referenced in load balancing.

In the "Backend" part, we use round-robin scheduling to distribute the load. "option forward for" specifies that HAProxy includes an "X-Forward-For" header when sending a connection request, which contains the client's IP address. This way the backend server will get the correct client IP.

"Option http_server_close" limits resources by eliminating any idle connections taking up server resources. Although WebSocket connections are long-lived, we must check if there are idle long-lived connections and close them to avoid unnecessary waste of resources.

Finally, add the backend servers that will be used to distribute traffic. Make sure to give the server the correct IP address and replace the IP address in the image below:

Your HAProxy is now configured for a WebSocket connection. Save changes and close file.

3. Validity test

Before restarting HAProxy, we can run a quick command to check that the file is valid and has no errors. To do this, run the following command:

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

4. Restart and test the WebSocket connection

After the file is valid, restart the HAProxy service.

That's it. You configured HAProxy for WebSocket connections. You can test the connection to ensure all WebSocket traffic is forwarded correctly.

in conclusion

Configuring HAProxy for WebSocket connections is a popular solution, especially among web administrators. This article elaborates on the process in detail, giving the steps and an example to ensure you are comfortable following and managing to implement the same process in your case. Work through each step to make sure you understand the concept and the process of implementing it.

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