Go's `net/http`: A Production-Ready Web Server

Why it exists

Go was designed for building networked services. The net/http package provides a robust, high-performance HTTP server directly in the standard library, enabling developers to create web applications and APIs without relying on third-party frameworks. This aligns with Go's philosophy of providing simple, powerful primitives.

The mental model

Think of net/http not as a rigid framework, but as a toolkit of building blocks. The central concept is the http.Handler interface. A handler is any object that has a ServeHTTP(w http.ResponseWriter, r *http.Request) method. Your entire web service is just a composition of these handlers, each responsible for a piece of logic.

How it works

You start a server with http.ListenAndServe(":8080", myMux). This function listens for TCP connections on a given address and port. For each incoming request, it calls the ServeHTTP method of the handler you provided (myMux). The handler is usually a router, called a ServeMux in Go. You register URL patterns and their corresponding handlers on this mux. For example, myMux.HandleFunc("/users", handleGetUser) tells the mux to execute the handleGetUser function for requests to the /users path.

When to use it

Use net/http for building APIs, microservices, and simple web applications where you want full control and minimal dependencies. It's perfect for performance-critical services because there's very little overhead between the network connection and your code. It is the idiomatic starting point for most Go web services.

When not to use it

For large applications, a full-featured framework might be more productive. The standard library's ServeMux is limited; it doesn't support path parameters (like /users/:id) or HTTP method-based routing out of the box. While you can build this yourself, using a third-party router is common practice.

One canonical example

The simplest server uses http.HandleFunc to register a handler on the default ServeMux. Calling http.ListenAndServe(":8080", nil) starts the server, with nil telling it to use this default mux. The biggest footgun is this global ServeMux; any imported package can register a route on it, potentially causing conflicts or security issues. Best practice is to create your own mux with http.NewServeMux() for explicit control.