I've been learning and experimenting with Golang in the past few days. I wanted to learn Go by developing something I thought would be useful.

Sharing interesting articles, videos and blog posts with my friends is something I enjoy doing all the time.

URLs these days are getting longer and complex, with APIs and Microservices Architecture all the rage! So, I find myself using URL Shorteners like TinyURL or Bitly all the time. I find large, clunky links very unusable.

And, thus the Idea was born. A Simple Golang URL Shortener, in the Command Line.

Go gopher

In this tutorial, I will be using the TinyURL API to shorten the long URLs. (I'm just too lazy to visit the website :P)

package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
)

Let us create a Package named main. The main package is where any Go program starts execution. We will also import the following packages.

  1. fmt - For formatting our outputs
  2. io - This the Input/Output package, all reads, writes and copying is done through this package.
  3. log - Who doesn't need logging?
  4. net/http - We import this package for making the HTTP GET Requests.
  5. os - To get the command line arguments that we need.

In the main function, add

fmt.Println("Tiny URL API consumption")

	if len(os.Args) != 2 {
		fmt.Fprintf(os.Stderr, "Usage: %s URL\n", os.Args[0])
		os.Exit(1)
	}

The if condition checks whether we have the required number of Command Line parameters. os.Args[0] refers to the filename and os.Args[1] refers to the URL we want to shorten. Those familiar with C should find this right at home.
Every Go program needs a filename to execute.

baseUrl := "http://tinyurl.com/api-create.php?url="
	urlToShorten := os.Args[1]
	getReqUrl := baseUrl + urlToShorten

	response, err := http.Get(getReqUrl)
	if err != nil {
		log.Fatal(err)
	} else {
		defer response.Body.Close()
		_, err := io.Copy(os.Stdout, response.Body)
		if err != nil {
			log.Fatal(err)
		}
	}

In the above code block, we construct the URL for the API call by using the variable baseURL and the URL to shorten.
We make a HTTP GET Call by using the http.Get method. To know more about HTTP Methods, click here

If the error we get isn't nil, then we can proceed. For the Java guys out there, nil is similar to null.

We are in luck here because the API Call returns a simple text which we output to the Standard Output, i.e. to the Terminal.

And thus, we have in our hands a Simple Command Line URL Shortener built in Go.

To build and run the program,

$ go build <the_program_name>
$ ./tinyurl_api <your_url>

You can also build and run in one go, like:

$ go run <the_program_name>

Here's the full code:

Example output:

$ go run https://google.co.in

$ Tiny URL API consumption
  http://tinyurl.com/4yc3v8u

Happy Coding!