A simple web server in Go

The Go programming language is well-known for having a built-in web server. In this article you will learn how you can easily make your own web server with Go. You won’t need any other packages beside the ones that are already built in!

It is recommended that you first do the excellent Tour of Go found here: https://tour.golang.org/ in order to gain some initial understanding in the Go programming language(Golang), however it is not required.

First, hop in to your text editor of choice. Then create a file, the name doesn’t matter but let’s call it webserver.go and enter the following code:

package main import ( "net/http" "io" ) func main() { http.HandleFunc("/", servePage) http.ListenAndServe(":8080", nil) } func servePage(writer http.ResponseWriter, request *http.Request) { io.WriteString(writer, "Hello world!") }

Let’s break down the block of code above. We import the net/http package: this package contains the web server itself, if you continue with Go as a web development language, be prepared to use this package often. Then we also import the io package, we will make use of this later to actually serve something to the client.

In the main function(denoted by package main), we do two things. First, we instruct the server to let the function called servePage handle all incoming traffic to / – in this case, it means that it handles requests to any URL path. The second thing we do is actually activating the server. We do this using a function named ListenAndServe. This function requires two parameters: the port (as a string date type), in this case it’s 8080, and the handler (as Handler) – however the last one isn’t important yet. We will just make it nil and everything will work just fine.

In the servePage we do just one simple thing, for now. Using the io package and the WriteString function that it contains we can respond to the clients’ request with the text Hello world! (or any string you choose, of course). You also might have noticed that the servePage function has two arguments: the writer and the request. With the writer you can actually respond to a HTTP request and with the request you may get more information about the request itself.

Congratulations! You just created your first web server! If you want to test it: just run go run webserver.go in your terminal, fire up a browser and navigate to http://localhost:8080!

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