`docker-http-https-echo`: An Essential Tool for Network Debugging

In the complex world of distributed applications, debugging network issues, proxies, load balancers, or firewall rules can be an arduous task. We need a simple way to verify what a server is receiving. This is where a tool like mendhak/docker-http-https-echo becomes indispensable.

What is mendhak/docker-http-https-echo?¶

It is an extremely lightweight and simple Docker container that functions as an "echo" HTTP and HTTPS server. Its main function is to respond to any HTTP or HTTPS request with a detailed description of the request itself. This includes:

• Request headers.
• HTTP method (GET, POST, PUT, etc.).
• Request URL and parameters.
• Request body.
• Remote IP address of the client.
• TLS/SSL information (if HTTPS).

Why is it useful?¶

This type of echo server is invaluable for a variety of debugging scenarios:

• Proxy and Load Balancer Debugging: Verify if a reverse proxy or load balancer is rewriting headers, modifying URLs, or passing the request body as you expect.
• Firewall and Security Rules: Confirm that traffic is reaching the correct destination and is not being blocked or altered.
• HTTP/HTTPS Header Inspection: Useful to see exactly what headers your client or a specific application sends.
• Integration Testing: A predictable target for automated tests of how different services communicate via HTTP/HTTPS.
• Mixed Content Diagnosis: You can use it to verify if HTTP resources are loading correctly in an HTTPS context.

How to Use It¶

Using it is straightforward via Docker:

For HTTP (port 8080)¶

docker run -p 8080:8080 mendhak/http-https-echo

Then, you can access http://localhost:8080 with your browser or curl:

curl http://localhost:8080/path?query=value -H "X-Custom-Header: test"

For HTTPS (port 8443)¶

To use HTTPS, you must map the container's HTTPS port. The image already comes with a self-signed certificate for testing.

docker run -p 8443:8443 mendhak/http-https-echo

Access https://localhost:8443 (your browser may warn you about the self-signed certificate).

Conclusion¶

mendhak/docker-http-https-echo is one of those simple but incredibly useful tools that every developer and system operator should have on hand. It facilitates understanding network flows and speeds up debugging connectivity issues in any container-based environment.

Original repository: mendhak/docker-http-https-echo on GitHub