To create a web server in Golang, use the net/http package. Define handlers and start a server to listen for incoming requests.

Creating a web server is one of the most common tasks in web development, and Golang (Go) makes it simple and efficient with its built-in net/http package. In this guide, we’ll walk through the steps to create a basic web server that can respond to HTTP requests.

1. Import the Required Packages

• Start by importing the net/http and fmt packages:

  import (
      "fmt"
      "net/http"
  )
  

2. Define a Request Handler

• A request handler is a function that processes incoming requests and sends back responses. Here’s a simple handler function:

  func helloHandler(w http.ResponseWriter, r *http.Request) {
      fmt.Fprintf(w, "Hello, World!")
  }
  

• This function writes a simple greeting to the response writer.

3. Set Up Routing

• Use the http.HandleFunc function to associate a URL pattern with a handler:

  func main() {
      http.HandleFunc("/hello", helloHandler)
  }
  

• This sets up the server to respond to requests made to the /hello endpoint with the helloHandler function.

4. Start the Web Server

• To start the server, use the http.ListenAndServe function:

      err := http.ListenAndServe(":8080", nil)
      if err != nil {
          fmt.Println("Error starting server:", err)
          return
      }
  }
  

• This listens on port 8080 for incoming HTTP requests.

5. Complete Program Example

• Here’s how everything comes together in a complete Go program:

  func main() {
      http.HandleFunc("/hello", helloHandler)
      err := http.ListenAndServe(":8080", nil)
      if err != nil {
          fmt.Println("Error starting server:", err)
          return
      }
  }
  

• This program starts a web server that listens on port 8080 and responds with "Hello, World!" when the /hello endpoint is accessed.

6. Testing the Server

• To test the server, open a web browser or use a tool like curl or Postman to navigate to http://localhost:8080/hello. You should see the message displayed.

7. Handling Different Routes

• You can set up multiple routes by defining additional handler functions and calling http.HandleFunc for each route:

  func goodbyeHandler(w http.ResponseWriter, r *http.Request) {
      fmt.Fprintf(w, "Goodbye, World!")
  }
  
  func main() {
      http.HandleFunc("/hello", helloHandler)
      http.HandleFunc("/goodbye", goodbyeHandler)
      err := http.ListenAndServe(":8080", nil)
      if err != nil {
          fmt.Println("Error starting server:", err)
          return
      }
  }
  

• This program adds another route that responds to /goodbye with a different message.

8. Conclusion Creating a web server in Golang is straightforward and powerful. With the net/http package, you can quickly set up routes, define handlers, and serve HTTP requests. As you progress, explore more advanced topics like middleware, routing libraries, and handling JSON responses for a full-fledged web application.