Too Long; Didn't Read

@tiago-melo

Senior Software Engineer

VSCode, also known as Visual Studio Code, is a highly versatile and feature-rich code editor that has won the hearts of developers worldwide. With its clean and intuitive interface, it provides a delightful coding experience, making it a top choice for many professionals and enthusiasts alike.

In a previous article of mine, we saw how to configure useful user snippets. Now I want to explore its debugging capabilities.

In this short article, we'll see how to debug a CLI app written in Golang.

Sample CLI

Here's our very simple app, which takes command-line arguments:

cmd/main.go

package main


import (
    "fmt"
    "os"


    "github.com/jessevdk/go-flags"
)


var opts struct {
    Name  string `short:"n" long:"name" description:"name" required:"true"`
    Age   int    `short:"a" long:"age" description:"age" required:"true"`
    Email string `short:"e" long:"email" description:"email" required:"true"`
}


func run(args []string) {
    flags.ParseArgs(&opts, args)
    fmt.Printf("opts.Name: %v\n", opts.Name)
    fmt.Printf("opts.Age: %v\n", opts.Age)
    fmt.Printf("opts.Email: %v\n", opts.Email)
}


func main() {
    run(os.Args)
}

Once again, as I did in this article about Golang, Kafka, and MongoDB real-time data processing, I'm using github.com/jessevdk/go-flags instead of the core flag package since it has several advantages.

To run it, we do:

$ go run cmd/main.go --name Tiago --age 39 --email [email protected]
Name: Tiago
Age: 39
Email: [email protected]

Nice. Of course, we're not doing anything useful in this simple app. But what if we have a complex CLI app and need to debug it?

Debugging it

In VSCode, click on "Run and Debug" and then "create a launch.json file":

Next, select "Go: Launch Package" option and hit enter:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Launch Package",
            "type": "go",
            "request": "launch",
            "mode": "auto",
            "program": "cmd/main.go",
            "args": [
                "--name",
                "Tiago",
                "--age",
                "39",
                "--email",
                "[email protected]"
            ]
        }
    ]
}

• program is the path to the file that contains the `main` function
• args is the string array where you pass the desired command line arguments

When you save it, the "Run and Debug" view will look like this:

Now, back to "Run and Debug" view; just click on the green play icon: