HTTP Server Basics

HTTP Server Basics

Go's standard library includes a production-ready HTTP server in the net/http package — no third-party framework needed. This is one of Go's great strengths: you can build high-performance web servers using only the standard library. The HTTP server handles concurrent requests automatically using goroutines, making it naturally scalable. Understanding the http.Handler interface, multiplexers, and middleware patterns is the foundation for building web services in Go.

Basic HTTP Server

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
)

func homeHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Welcome to the Go server!")
}

func apiUsersHandler(w http.ResponseWriter, r *http.Request) {
    users := []map[string]interface{}{
        {"id": 1, "name": "Alice"},
        {"id": 2, "name": "Bob"},
    }
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(users)
}

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("GET /", homeHandler)
    mux.HandleFunc("GET /api/users", apiUsersHandler)

    fmt.Println("Server starting on :8080")
    log.Fatal(http.ListenAndServe(":8080", mux))
}

Middleware

func loggingMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        log.Printf("%s %s", r.Method, r.URL.Path)
        next.ServeHTTP(w, r)
    })
}

// Chain middleware
handler := loggingMiddleware(corsMiddleware(mux))
http.ListenAndServe(":8080", handler)

Pro tip: Go 1.22+ supports method-based routing in the default mux: mux.HandleFunc("GET /users/{id}", handler). For complex routing, consider the chi or gin routers which add path parameters, middleware groups, and other features while keeping the standard http.Handler interface.

Key Takeaways

• Go's net/http package provides a production-ready HTTP server with no external dependencies.
• Handlers implement http.Handler or use http.HandlerFunc for simpler function-based handlers.
• Middleware wraps handlers to add cross-cutting concerns like logging, auth, and CORS.
• The server handles concurrency automatically — each request runs in its own goroutine.
• Use json.NewEncoder(w).Encode(data) for streaming JSON responses.