Gluegun provides a builder that lets you initialize and configure Gluegun to work with your CLI. It lets you load & execute commands, extensions, and plugins.

Note: Check out the sniff module for detecting if your environment is able to run.

Here's a kitchen sink version, which we're about to cover.

const { build } = 'gluegun'

const cli = build('movie')
  .src(__dirname)
  .plugin('~/.movie/movie-imdb')
  .plugins('./node_modules', { pattern: 'movie-' })
  .help()
  .version()
  .defaultCommand()
  .command({ name: 'hi', run: toolbox => toolbox.print.info('hi!') })
  .exclude(['filesystem', 'semver', 'system', 'prompt', 'http'])
  .checkForUpdates(5) // check for updates randomly about 5% of the time
  .create()

await cli.run()

build

Grab the build function from gluegun.

const { build } = require('gluegun')

Now let's build a gluegun cli environment by configuring various features.

const cli = build('mycli')

The mycli brand that you pass into build is used through-out gluegun for things like configuration file names and folder names for plugins. You can also set it later, like this:

const cli = build().brand('movie')

Out of the box, this CLI does very little. And by very little I mean nothing. So let's configure this. We'll be chaining the build() function from here.

src

This sets where the default commands and extensions are located, in commands and extensions folders, respectively.

const cli = build('movie').src(__dirname)

When you run a command, it'll first load extensions in this folder and then check the commands in this folder for the right command.

# run a command with arguments
$ movie actors Kingpin

# run a command with arguments & options
$ movie producers "Planes, Trains, & Automobiles" --sort age

plugin

Additional functionality can be added to the gluegun object with plugins. Plugins can be yours or your users.

Hint: src and plugin are almost identical under the hood. The only thing they do differently is src will be loaded first and be the "default plugin".

A plugin is a folder (or, more often, an NPM package) that contains a structure - something like this:

movie-credits
  commands
    actors.js
    producers.js
  extensions
    retrieve-imdb.js
  templates
    actor-view.js.ejs
  movie.config.js

You can load a plugin from a directory:

const cli = build('movie')
  .src(__dirname)
  .plugin('~/.movie/movie-imdb')

plugins

You can also load multiple plugins within a directory.

const cli = build('movie')
  .src(__dirname)
  .plugin('~/.movie/movie-imdb')
  .plugins('./node_modules', { pattern: 'movie-' })

plugins supports a fs-jetpack matching pattern so you can filter out a subset of directories instead of just all.

  .plugins('./node_modules', { matching: 'movies-*' })

If you would like to keep plugins hidden and not available at the command line:

  .plugins('./node_modules', { matching: 'movies-*', hidden: true })

When plugins are hidden they can still be run directly from the cli.

help

Gluegun ships with a somewhat adequate help screen out of the box. Add it to your CLI easily by calling .help().

const cli = build('movie')
  .src(__dirname)
  .plugins('./node_modules', { pattern: 'movie-' })
  .plugin('~/.movie/movie-imdb')
  .help()

You can also pass in a function or command object here:

  .help(toolbox => toolbox.print.info('No help for you!'))
  .help({
    name: 'help',
    alias: 'helpmeplease',
    hidden: true,
    dashed: true,
    run: toolbox => toolbox.print.info('No help for you!')
  })

version

You usually like to be able to run --version to see your CLI's version from the command line, so add it easily with .version().

const cli = build('movie')
  .src(__dirname)
  .plugins('./node_modules', { pattern: 'movie-' })
  .plugin('~/.movie/movie-imdb')
  .help()
  .version()

Just like help above, you can pass in a function or command object to configure it further.

defaultCommand

If the user runs your CLI and doesn't supply any matching parameters, it'll run this command instead. Note that you can do this by supplying a <brand>.js file in your ./commands folder as well.

const cli = build('movie')
  .src(__dirname)
  .plugins('./node_modules', { pattern: 'movie-' })
  .plugin('~/.movie/movie-imdb')
  .help()
  .version()
  .defaultCommand()

Just like help and version above, you can pass in a function or command object if you prefer more control.

command

If you want to pass in commands directly to the runtime builder, you can do that with .command().

const cli = build('movie')
  .src(__dirname)
  .plugins('./node_modules', { pattern: 'movie-' })
  .plugin('~/.movie/movie-imdb')
  .help()
  .version()
  .defaultCommand()
  .command({ name: 'hi', run: toolbox => toolbox.print.info('hi!') })

In this case, if you ran movie hi, it would run the function provided and print out 'hi!'.

You must provide an object with at least a name and a run function, which can be async or regular.

exclude

If you don't need certain core extensions, you can skip loading them (thus improving startup time) by using .exclude(). Just pass in an array of string names for the core extensions you don't need.

const cli = build('movie').exclude([
  'meta',
  'strings',
  'print',
  'filesystem',
  'semver',
  'system',
  'prompt',
  'http',
  'template',
  'patching',
])

If you find you need one of these extensions for just one command but don't want to load it for all of your commands, you can always load it separately from the Gluegun toolbox, like this:

const { prompt } = require('gluegun')
// or
const { prompt } = require('gluegun/prompt')

For reference, the core extensions that incur the biggest startup performance penalty are (timing varies per machine, but this gives some sense of scale):

prompt +100ms
print +45ms
http +30ms
system +10ms

Note about TypeScript and exclude: Please note that the TypeScript type GluegunToolbox (as of Gluegun 2.1.x) always assumes that core extensions are included, even if you excluded them in the builder. In this case, it's recommended that you create your own FooToolbox (or similar) and update the interface to match your preferred configuration. Example:

// wherever your types are, say, `./src/types.ts`
import { GluegunToolbox } from 'gluegun'
export interface FooToolbox extends GluegunToolbox {
  prompt: null
  print: null
  http: null
  system: null
}

// in a command
import { FooToolbox } from '../types'
module.exports = {
  run: async (toolbox: FooToolbox) => {
    // ... use toolbox with your excluded extensions
  },
}

checkForUpdates

This allows you to check for updates every so often. Because we don't track how often your CLI is run, instead, we allow you to set a percentage chance of checking for updates. We recommend somewhere between 1-20, depending on how often your CLI is run. If you want to run it every time, set it to 100.

const cli = build('movie')
  .src(__dirname)
  .plugins('./node_modules', { pattern: 'movie-' })
  .plugin('~/.movie/movie-imdb')
  .help()
  .version()
  .defaultCommand()
  .command({ name: 'hi', run: toolbox => toolbox.print.info('hi!') })
  .checkForUpdates(5)

create

At this point, we've been configuring our CLI. When we're ready, we call create():

const cli = build('movie')
  .src(__dirname)
  .plugins('./node_modules', { pattern: 'movie-' })
  .plugin('~/.movie/movie-imdb')
  .help()
  .version()
  .defaultCommand()
  .command({ name: 'hi', run: toolbox => toolbox.print.info('hi!') })
  .checkForUpdates(5)
  .create()

This command applies the configuration that you were just chaining, and turns it into a runtime cli which supports calling run().

And now we're ready to run:

cli.run()

With no parameters, gluegun will parse the command line arguments looking for the command to run.

# list the plugins
$ movie

# run a command
$ movie quote

# run a command with options
$ movie quote --funny

# run a command with arguments
$ movie actors Kingpin

# run a command with arguments & options
$ movie producers "Planes, Trains, & Automobiles" --sort age

run

gluegun can also be run() with options.

await cli.run('quote random "*johnny"', {
  funny: true,
  genre: 'Horror',
  weapon: 'axe',
})

There's a few situations that make this useful.

Maybe you like to use meow or commander to parse the command line.
Maybe your interface isn't a CLI.
Maybe you want to run several commands in a row.
Maybe this is your program and you don't like strangers telling you how to code.

Bottom line is, you get to pick. It's yours. gluegun is just glue.

configuration

Each plugin can have its own configuration file where it places defaults. These defaults can then be overridden by reading defaults from a configuration file or entry in package.json. We use cosmiconfig for this.

It will read the plugin name from the name key and the defaults will be read from the defaults section. Each section underneath default can be used to override the sections of the plugin. Since that was horribly explained, here's an example.

// in movies.config.js
module.exports = {
  name: 'movies',
  defaults: {
    movie: {
      cache: '~/.movies/cache',
    },
    another: {
      count: 100,
    },
  },
}

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