gocli.slide

# go-cli

Mehul Gohil
19 June 2023
mehul.gohil@talentica.com

## CLI (Command Line Interface)
- Text Based User Interface
- Requires Terminal
- Examples: terraform, kubectl, aws, az etc
- CLIs helps us to store script to automate regular tasks.

## CLIs in Go

- Complies really quick.
- The build binary can be use cross OS and architectures.
- It requires no complicated build farms.
- The platform running the go program doesn't requires any external dependencies or runtime.

.image cli.jpg

## Creating CLI the traditional way

.play traditional-cli/main.go

## Snakes comes to rescue...

- Cobra
    - Library
    - Nested Subcommands
    - Global, Local and Cascading Flags
    - Automatic Help Commands
    - Fully POSIX-compliant flags (including short & long versions)

- Viper
    - Complete configuration solution
    - Setting defaults
    - Reading from JSON, TOML, YAML, HCL etc

## Setting up Cobra

    cobra-cli init gotodo               # To initialize the main command

    cobra-cli add list                  # To add additional command

Sub Command

    cobra-cli add search                # To add search command

    cobra-cli add search completed      # To add a subcommand completed to search command

Usage

    gotodo list                         # Command use to list of all the todo tasks

    gotodo search                       # Command use to search the task

    gotodo search completed             # `completed` subcommand to search for all completed tasks

## Setting up Flags
- Flags
    - Local Flags (Assigned to single command)

            searchCmd.Flags().StringP("keyword", "k", "", "Keyword for the task name to search for.")
        Usage

            gotodo search -k test

    - Persistent Flags (Assigned to command and sub command)

            searchCmd.PersistentFlags().StringP("output", "o", "", "Output format [table, json, yaml]")
        Usage

            gotodo search -o yaml

## Setting up Args
.code cmd/complete.go /^//START/,/^//END/

Usage

    gotodo complete 1                         # Command to complete task 1

## Viper Set up
.code cmd/load.go /^//START/,/^//END/

Usage

    gotodo load --jsonFile storage1.json      # Command to load existing json tasks