Brocolito

Brother command line tool

Create type-safe CLIs to align local development and pipeline workflows.

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What you get

Ever wanted a type safe, easy to set up CLI that is automatically self-updating locally and can be used in CI / CD workflows? Brocolito aims to support you with that.

How to

pnpm create brocolito-cli
# or
npx create-brocolito-cli
# or
yarn create brocolito-cli

Then cd into your CLI and run pnpm build.

Feel free to check out the herein provided example.

Minimal code sample

In your src/main.ts you create this code:

import { CLI } from 'brocolito';

CLI.command('hello').action(() => console.log('hello world'));

CLI.parse(); // this needs to be executed after all "commands" were set up

Now you can run cli -h to see the help message or cli hello to print hello world.

For more advanced features see below.

Setup in GitHub Actions

Please check the used custom actions of this repository yourself. It uses pnpm to install the CLI dependencies and a simple setup to set up the CLI.

In this workflow you can see it in action.

CLI features

The CLI contains already many features right away. It was inspired by commander and cac, but it has a slightly different API and some features that I was found to be missing like native subcommand and tab completion support.

Help

Using the -h or --help options on any command, subcommand or top-level will display an automatically generated help text from your CLI configuration.

Completion

As soon as you have locally set up the completion, you will get automatically suggestions based on your CLI configuration. Run cli completion to set up the tab completion.

Completion for aliases

If you want to use an alias for e.g. one of your subcommands like cli get data, you have to register it to make the completion work like so: CLI.alias('cgd', 'cli get data').

Completion for options and args

You can run (async) functions to return the completion results for options and args of type string or file by passing it as third argument when specifiying the option/arg. E.g.,

CLI.command("do", "...")
   .option("--service <string>", "name of the service", {
      // "filter" is the string the user has already typed when running the completion
      // ATTENTION: Filtering will work even if you would display all options, but
      //            it can improve performance to reduce the amount of processed data.
      completion: async (filter) => (await getAllServices({ filter })).map(({ name }) => name),
   });

Options

Options are basically named parameters for your command. The specified option names are accessible under their camelCase name. E.g. foo-bar becomes fooBar. Values for options can be specified using a space or = as separator, e.g. --my-option=foo and --my-option foo are identically treated, whereas --my-option without parameters is only valid for option flags and will be treated as boolean true.

Boolean Options (Flags)

• Specification: --option-name

• Parameter type: boolean

• Completion: true or false

• Code example:

  CLI.command('hello', 'prints hello world')
     .option('--with-exclamation-mark', 'append exclamation mark')
     .action(({ withExclamationMark }) => console.log(`hello world${withExclamationMark ? '!' : ''}`));

• Shell examples:

  cli hello --with-exclamation-mark
  cli hello --with-exclamation-mark=true
  cli hello --with-exclamation-mark false

String Options

• Specification: --option-name <string>

• Parameter type: string | undefined

• Completion: none

• Code example:

  CLI.command('hello', 'prints greeting')
     .option('--name <string>', 'who to greet?')
     .action(({ name }) => console.log(name ? `hello ${name}` : "Too shy to give me a name?"));

• Shell example: cli hello --name mark

File Options

• Specification: --option-name <file>

• Parameter type: string | undefined

• Completion: local file system

• Code example:

  CLI.command('char-count', { description: 'count characters', alias: 'cc' })
     .option('--content <file>', 'what file to use?')
     .action(async ({ content }) => console.log((await fs.readFile(content, 'utf-8')).length));

• Shell example: cli char-count --content ./foo.txt

Union Options

• Specification: --option-name <one|two>

• Parameter type: "one" | "two" | undefined

• Completion: one or two

• Code example:

  CLI.command('fancy-stuff', "do fancy stuff")
     .option('--log-level <debug|info|warn|error>', 'what debug level to use (default: error)')
     .action(({ logLevel = "error" }) => doFancyStuff({ logLevel }));

• Shell example: cli fancy-stuff --log-level debug

Multi Options

• Specification: --option-name <string...> or --option-name <one|two...>

• Parameter type: string[] | undefined or ("one" | "two")[] | undefined

• Completion: like for single options

• Code example:

  CLI.command('char-count', { description: 'count characters', alias: 'cc' })
     .option('--files <file...>', 'what files to use?')
     .action(async ({ files }) => files.forEach((f) => console.log((await fs.readFile(f, 'utf-8')).length)));

• Shell example: cli char-count --files ./foo.txt --files ./bar.json

Mandatory Options

• Specification: --option-name! <string>

• Parameter type: string

• Completion: like the non mandatory options

• Code example:

  CLI.command('hello', 'prints greeting')
     .option('--name! <string>', 'who to greet?')
     .action(({ name }) => console.log(`hello ${name}`));

• Shell example: cli hello --name mark

Args

Args are basically unnamed parameters or parameter lists. The specified arg names are accessible under their camelCase name. E.g. foo-bar becomes fooBar. You can have as many different args for the same command as you like. You cannot have args and subcommands on a command. If you cannot have another arg after an arg list.

String Arg

• Specification: <arg-name>

• Parameter type: string

• Completion: none

• Code example:

  CLI.command('hello', 'prints greeting')
     .arg('<arg-name>', 'greeting name')
     .action(({ argName }) => console.log(`hello ${name}`));

• Shell example: cli hello mark

File Arg

• Specification: <arg-name:file>

• Parameter type: string

• Completion: local file system

• Code example:

  CLI.command('exists', 'checks existance')
     .arg('<file-name:file>', 'what file to check?')
     .action(({ fileName }) => console.log(fs.existsSync(fileName)));

• Shell example: cli exists /tmp/someFile.js

Union Arg

• Specification: <arg-name:one|two>

• Parameter type: "one" | "two"

• Completion: one or two

• Code example:

  CLI.command('configure', 'configure settings')
     .arg('<env:dev|test>', 'chosen env')
     .action(configureEnv);

• Shell example: cli configure dev

Arg lists

• Specifications: <arg-name...> or <arg-name:file...>

• Parameter type: string[]

• Completions: none or local file system

• Code example:

  CLI.command('exists', 'checks existance')
     .arg('<file-names:file...>', 'what files to check?')
     .action(({ fileNames }) => console.log(fileNames.map((f) => fs.existsSync(f))));

• Shell example: cli exists /tmp/someFile.js ./foo.txt

Subcommands

Subcommands allow you to create a grouped functionality of commands within other commands. Subcommands can be as deeply nested as you like. If a command has subcommands it cannot have args. Options are inherited from the command to all afterwards specified subcommands. Every subcommand can use further options, args or subcommands as any regular command.

• Code example:

  CLI.command('string', 'do something with strings')
     .option('--error', 'logs as error')
     .subcommand('trim', 'trims a string', (sub) => {
     sub.arg('<str>').action(({ str, error }) => console[error ? 'error' : 'log'](str.trim()));
     })
     .subcommand('length', { description: 'counts the chars', alias: 'l' }, (sub) => {
     sub.arg('<str>').action(({ str, error }) => console[error ? 'error' : 'log'](str.length));
     })

• Shell examples:

  cli string trim " foo"
  cli string length "lorem ipsum"

Aliases

If you are using aliases for some commands, code completion would stop working correctly, if you don't register the aliases. E.g. if you have for that command my-cli foo an alias configured in your shell via alias cf=my-cli foo, then you need to configure it like this:

CLI.alias('cf', 'my-cli foo');

Extra features

brocolito makes use of some utilities that are also made available for your CLI.

• complainAndExit(msg: string): Prints the given message in red and immediately stops the process without printing a whole error stack.
• pc: Default export of the picocolors package to add colors to your printed output.
• prompts: Default export of the prompts package to make use of interactive shell prompts.

External dependencies

If you are using external dependencies, these have to be listed in your package.json under "dependencies". In case of build-in NodeJS dependencies, make sure to use the prefixed package names, e.g. node:fs instead of fs. Otherwise, the dependencies might end up included in your resulting bundle or aren't correctly resolved at all.