Build a small HTTP server

An HTTP server listens on a port, parses requests, routes method-plus-path pairs, runs application logic, and returns a status, headers, and body. Start with one health route before adding frameworks or databases.

At a glance

Question	Practical answer
When is it useful?	A tiny service answers GET /health with 200 and JSON, returns 404 for unknown paths, and rejects unsupported methods with 405.
What should you do?	Create the three routes using your language's standard library or a minimal framework, then call them with curl.
How do you know it worked?	curl shows the intended status and JSON for each route, and stopping the process releases the port cleanly.
Common failure	Binding to every network interface can expose a development server; use localhost until remote access is intentional and secured.

flowchart LR
  A[Question] --> B[Build a small HTTP server]
  B --> C[Small example]
  C --> D[Evidence]

The important idea is not to stop at a definition: connect the concept to a small example and observable evidence.

Worked example

A tiny service answers GET /health with 200 and JSON, returns 404 for unknown paths, and rejects unsupported methods with 405.

Before acting, write the success signal. Change one condition at a time, observe the result, and record assumptions. For Build a small HTTP server, this separates what you know from what you are merely guessing.

Practice in 20–30 minutes

Goal: Create the three routes using your language's standard library or a minimal framework, then call them with curl.

1. Record the starting state and your prediction.
2. Implement the smallest version without adding unnecessary tools.
3. Change exactly one input or constraint and repeat.
4. Save a command, screenshot, output, or checklist as evidence.

Expected result: curl shows the intended status and JSON for each route, and stopping the process releases the port cleanly.

What can go wrong

Binding to every network interface can expose a development server; use localhost until remote access is intentional and secured.

When the result differs from your prediction, do not change many things at once. Check inputs, versions, environment, permissions, and logs, then repeat from the smallest example.

Definition of done

• I can explain the concept in my own words.
• I completed the small example and kept evidence.
• I know one failure mode and how to check it.
• Someone else can repeat the work without guessing missing steps.

Go deeper

Use the linked resource or repository at the end of the page when you need a full implementation. Check current versions before applying commands to a real project.