Getting Started with Cobra

Welcome to Cobra! This tutorial will guide you through the essentials of installing Cobra and creating your first command-line application. By the end of this tutorial, you’ll have a working CLI application with your own custom command.

Prerequisites

Before we begin, make sure you have:

• Go 1.21 or later installed on your system
• Basic familiarity with Go development
• A terminal or command prompt

Step 1: Install Cobra and cobra-cli

First, let’s install the Cobra library and the cobra-cli tool that will help us generate our application structure:

go get -u github.com/spf13/cobra@latest

go install github.com/spf13/cobra-cli@latest

The first command adds Cobra as a dependency, while the second installs the cobra-cli generator tool that makes creating new applications and commands much easier.

Step 2: Create Your Application

Now let’s create your first CLI application using the cobra-cli tool:

cobra-cli init my-cli

Your Cobra application is ready at my-cli

Add commands to your application by using the `add` command

This creates a new directory called my-cli with a complete Go module and basic Cobra application structure. Let’s explore what was created:

cd my-cli

ls -la

total 16

drwxr-xr-x   6 user  staff   192 Aug 10 12:00 .

drwxr-xr-x   3 user  staff    96 Aug 10 12:00 ..

drwxr-xr-x   3 user  staff    96 Aug 10 12:00 cmd

-rw-r--r--   1 user  staff    87 Aug 10 12:00 go.mod

-rw-r--r--   1 user  staff   155 Aug 10 12:00 go.sum

-rw-r--r--   1 user  staff   615 Aug 10 12:00 main.go

Step 3: Test Your Base Application

Let’s test the basic application that was generated:

go run main.go

A longer description that spans multiple lines and likely contains

examples and usage of using your application. For example:

Cobra is a CLI library for Go that empowers applications.

This application is a tool to generate the needed files

to quickly create a Cobra application.

Great! Your base application is working. You can also test the built-in help:

go run main.go --help

A longer description that spans multiple lines and likely contains

examples and usage of using your application. For example:

Cobra is a CLI library for Go that empowers applications.

This application is a tool to generate the needed files

to quickly create a Cobra application.

Usage:

my-cli [flags]

Flags:

-h, --help   help for my-cli

Step 4: Add Your First Command

Now let’s add a custom command to make your CLI more interesting:

cobra-cli add hello

hello created at cmd/hello.go

This creates a new file cmd/hello.go with a hello command. Let’s test it:

go run main.go hello

hello called

Perfect! You now have a working command. Let’s see how it appears in the help:

go run main.go --help

A longer description that spans multiple lines and likely contains

examples and usage of using your application. For example:

Cobra is a CLI library for Go that empowers applications.

This application is a tool to generate the needed files

to quickly create a Cobra application.

Usage:

my-cli [command]

Available Commands:

completion  Generate the autocompletion script for the specified shell

hello       A brief description of your command

help        Help about any command

Flags:

-h, --help   help for my-cli

Use "my-cli [command] --help" for more information about a command.

Step 5: Customize Your Command

Let’s make the hello command more interesting by editing the generated file. Open cmd/hello.go and you’ll see the basic structure that cobra-cli created.

The key part is the Run function where you can add your custom logic:

go run main.go hello

Hello from your new Cobra CLI application!

You can also add flags to your command. Try the built-in help for your hello command:

go run main.go hello --help

A brief description of your command

Usage:

my-cli hello [flags]

Flags:

-h, --help   help for hello

Step 6: Build Your Application

Finally, let’s build your CLI application into an executable:

go build -o my-cli

./my-cli hello

Hello from your new Cobra CLI application!

Next Steps

Now that you have a working Cobra application, you can:

• Add more commands with cobra-cli add [command-name]
• Learn about flags and arguments in the My First CLI tutorial
• Explore command customization in the Customizing Your CLI tutorial
• Read the User Guide for comprehensive documentation

Happy coding with Cobra!