Building a Simple HTTP Server with Deno: Step-by-Step Guide

Creating a simple HTTP server from scratch in Deno is quite straightforward, thanks to its native support for serving HTTP requests. Below is a step-by-step guide to building a basic HTTP server using Deno:

Step 1: Install Deno

Ensure you have Deno installed on your system. If not, you can install it by following the instructions on the official Deno website.

Step 2: Create the HTTP Server

1. Create a new directory for your project:

   mkdir my_deno_http_server
   cd my_deno_http_server
   

2. Create a file named server.ts:

3. Write the server code inside server.ts:

   import { serve } from "https://deno.land/std@0.115.1/http/server.ts";
   
   const port = 8000;
   const server = serve({ port });
   
   console.log(`HTTP server is running on http://localhost:${port}/`);
   
   for await (const request of server) {
     const url = new URL(request.url);
     let responseText = "";
   
     // Basic routing
     if (url.pathname === "/") {
       responseText = "Welcome to the Deno HTTP server!";
     } else if (url.pathname === "/about") {
       responseText = "This is a sample Deno HTTP server.";
     } else {
       responseText = "404 Not Found";
     }
   
     request.respond({ body: responseText });
   }
   

4. Run the server: Open a terminal in your project directory and execute the following command:

   deno run --allow-net server.ts
   

   The --allow-net permission is required because the script needs to access the network to run the HTTP server.

Step 3: Test the Server

1. Access the server in a web browser or via a tool like curl:

   • Open a browser and visit http://localhost:8000/. You should see the message "Welcome to the Deno HTTP server!".
   • Visit http://localhost:8000/about to see the message "This is a sample Deno HTTP server."
   • Any other URL will return "404 Not Found".

2. You can also test using curl:

   curl http://localhost:8000/
   curl http://localhost:8000/about
   curl http://localhost:8000/unknown
   

This is a very simple server that can serve basic text responses based on the URL path. This example demonstrates how to handle different URL paths, a basic feature of routing, and serves as a starting point for building more complex HTTP solutions using Deno.