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Abdulmuhaimin1219
Abdulmuhaimin1219

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Cobra CLI in Go

#go #devops #linux #cloud

Introduction

Unlike Node.js, where a project already comes with the npm CLI and script handling via package.json, Go projects don’t have a built‑in CLI for scripting. Instead, they rely on external adapters. Today I learned how to use Cobra CLI to handle this, and I’ll walk you through the basics.

Installing Cobra CLI

First, install Cobra CLI with:

go get -u github.com/spf13/cobra@latest && \
go install github.com/spf13/cobra-cli@latest
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Initializing Your Project

Run:

cobra-cli init
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This command generates a main.go file and a cmd folder containing a root.go file. The root.go file is where core CLI configurations are set up. You can also use this file for essential initialisations; for example, in my study case, I initialised the database connection within my project.

Creating Your Own Command

To create a new, custom command for your application, use the add command:

cobra-cli add NAME-OF-COMMAND
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If I use cli as the name, Cobra generates a new file (e.g., cli.go). This file includes basic description information that you can modify as needed.

Defining Logic and Flags
Inside the generated command file (e.g., cli.go), I need to declare the variables that my function requires.

In the generated init function, I create the flags that my command can receive and associate each flag's value with a variable.


// Example of flag creation in the `init` function
func init() {
    // ... other code ...

    // Define flags and bind them to variables
    cliCmd.Flags().StringVarP(&action, "action", "a", "read", "Action to perform (create/read/update/delete)")
    cliCmd.Flags().StringVarP(&productName, "product", "p", "", "Name of the product")
    cliCmd.Flags().Float32VarP(&productPrice, "price", "r", 0.0, "Price of the product")
}

// Example of command execution in the Run function
func run(cmd *cobra.Command, args []string) {
    // Logic goes here
    fmt.Printf("Action: %s, Product: %s, Price: %.2f\n", action, productName, productPrice)
    // In a real app, this would call a function to interact with the database
}
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Then, if I run the following command:

go run main.go cli -action=create -product=Produto -price=25.0
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I am assigning values to the variables (action, productName, and productPrice), and the Run function can then use them to, for example, create a new product in the database.

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