Mini HTTP Server in Go

A lightweight, optimized HTTP server implementation in Go, built from scratch without using the standard library's HTTP package. This project demonstrates core HTTP server concepts including request parsing, routing, and response handling.

Features

HTTP Protocol Implementation

• Custom HTTP/1.1 protocol implementation
• Request parsing and header handling
• Response generation with proper status codes
• Connection management with timeouts

Routing System

• Path-based routing with regex pattern matching
• Support for URL parameters (e.g., /users/:id)
• HTTP method-based routing (GET, POST)
• Custom 404 Not Found handler

API Endpoints

• /v1/healthcheck - Server health check endpoint
• /v1/echo/:str - Echo service that returns the URL parameter
• /v1/user-agent - Returns the User-Agent header from the request

Error Handling

• Proper HTTP status codes (200, 400, 404, 500)
• Graceful error recovery with panic handling
• Detailed error logging

Architecture

Core Components

Server

• Handles TCP connections and converts them to HTTP requests
• Manages connection timeouts and error recovery
• Dispatches requests to the appropriate handlers

Router

• Maps URL patterns to handler functions
• Supports parameter extraction from URLs
• Handles method-based routing (GET, POST)

Request/Response

• Custom implementation of HTTP request parsing
• Response writer with header management
• Buffered I/O for efficient network operations

Configuration

• Environment variable support
• Command-line flag integration
• Configurable port settings

Usage

Starting the Server

# Start with default port (4221)
./run.sh

# Start with custom port
./run.sh -port=8080

# Or using environment variable
PORT=8080 ./run.sh

Making Requests

# Health check
curl http://localhost:4221/v1/healthcheck

# Echo service
curl http://localhost:4221/v1/echo/hello-world

# User agent
curl http://localhost:4221/v1/user-agent

Development

Project Structure

• app/main.go - Entry point and application setup
• app/server.go - Core HTTP server implementation
• app/routes.go - Routing system implementation
• app/feature_routes.go - API endpoint handlers
• app/header.go - HTTP header and request parsing
• app/env.go - Configuration and environment handling
• app/errors.go - Error handling utilities

Adding New Routes

To add a new route, implement a handler function and register it in the Routes() function in routes.go:

// 1. Create a handler function
func (app *application) NewEndpoint(w ResponseWriter, r *Request) {
    w.Write(StatusOK, []byte("This is a new endpoint"))
}

// 2. Register the route in Routes()
func (app *application) Routes() HttpHandler {
    router := NewRouter()

    // Existing routes
    router.GET("/v1/healthcheck", app.Healthcheck)

    // New route
    router.GET("/v1/new-endpoint", app.NewEndpoint)

    return router
}

Performance Considerations

• Uses buffered I/O for efficient network operations
• Implements connection timeouts to prevent resource exhaustion
• Handles each connection in a separate goroutine for concurrency