metapak

metapak

Node modules authoring made easy.

What's that?

metapak provides a set of tools to build your own meta npm packages easily.

A meta npm package takes advantage of npm lifecycle scripts to allow you to manage several similar npm packages/NodeJS projects in a simple and versioned way.

Here is a simple deck introducing it.

What is it good for?

Let's say you are the author of thousands of Node modules. Now, imagine you want, for all of them:

• change your linter,
• change your license,
• change your CI provider,
• add a README template system,
• add a contributors guide,
• setup git hooks.

This could look like a developer nightmare but with metapak you can manage that complexity by creating idempotent scripts to run on all your projects.

Features

Allows you to create a npm meta module to:

• amend all your npm modules package.json globally, in a composable way (shared dependencies, utility scripts etc...),
• add assets to all your projects without polluting your git history with insignificant changes,
• automatically install git hooks so that all your coding flow are respected by your contributors.

metapak can handle several meta packages so that you can compose them easily and keep them small and focused on one concern.

Zero config for your contributors, nothing to install globally.

Usage

First create your own metapak module (you can look at mine to grasp its architecture).

You must name your module with the metapak- prefix in order to make it work.

Now, just define the states of all your Node modules:

mkdir src
mkdir src/_common

# Let's set the package.json of all your modules
# Note this has to be an idempotent function
# (ie: same run same result)
echo "
module.exports = (packageConf) => {
  // Looks like i am the contributor of all
  // my modules ;)
  packageConf.author = 'Nicolas Froidure';

  // I mostly publish under MIT license,
  // let's default to it
  packageConf.license = 'MIT';

  // Let's add my handy scripts
  packageConf.scripts = packageConf.scripts || {};
  packageConf.scripts.cli = 'env NODE_ENV=${NODE_ENV:-cli}';

  // And the MUST HAVE dependencies
  packageConf.dependencies = packageConf.dependencies || {};
  packageConf.dependencies.debug = '1.0.0';

  // And the MUST HAVE dev dependencies
  packageConf.devDependencies = packageConf.devDependencies || {};
  packageConf.devDependencies.eslint = '3.0.0';

  return packageConf;
}" > src/_common/package.js

# Let's also add some common assets
# metapak will add/update for us
mkdir src/_common/assets
# Adding the license
wget -O src/_common/assets/LICENSE https://mit-license.org/license.txt
# Adding a git ignore file
# Note we replaced the dot of the file per _dot_
# This is due to a magic behavior of npm
# See: https://github.com/npm/npm/issues/15660
# metapak will rename it to .gitignore
echo "node_modules" > src/_common/assets/_dot_gitignore

# And make some additions to them, like templating
echo "
module.exports = (file, packageConf) => {
  // Simple templating of the LICENSE
  // There is no glob matching or templating system
  // in metapak to let you choose the ones you like
  if(file.name === 'LICENSE') {
    file.data = file.data.replace(
      /<copyright holders>/g,
      'Nicolas Froidure'
    );
    return file;
  }
  return file;
};
" > src/_common/assets.js

# Finally let's add my git hooks on it
echo "module.exports = (hooks, packageConf) => {
  hooks['pre-commit'] = hooks['pre-commit'] || [];

  // Ensure tests and linting are ok
  hooks['pre-commit'].push('npm run test && npm run lint || exit 1');

  // Ensure that metapak state is stable
  // Indeed, you do not want to commit
  // while metapak has some changes to do
  // doing so would create a gap between
  // you metapak module/config and the
  // repository contents
  hooks['pre-commit'].push('npm run metapak -- --safe || exit 1');
  return hooks;
};
" > src/_common/hooks.js

For convenience, you can add a post install script and a peer dependency to your metapak plugin for a better user experience:

{
  "scripts": {
    "postinstall": "npm run metapak",
  },
  "peerDependencies": {
    "metapak": "^2.0.0"
  },
}

Now publish your package to npm and install it in all your repositories development dependencies with metapak:

npm i --save-dev metapak metapak-nfroidure

That's it! There is a lot of things you can set on all your projects like CI scripts, linters, tests configuration etc...

You can also create specific configs and combine them. Let's say I work for the Big Brother inc. and i want to add special behaviors for the modules I create at work:

mkdir src/bigbrother

# Let's add a package.json template
echo "
module.exports = (packageConf) => {
  // Lets proudly claim I work at BB inc.!
  packageConf.author = 'Nicolas Froidure (Big Brother inc.)';

  // Let's change the license
  packageConf.license = 'SEE LICENSE IN LICENSE.md';

  // Let's avoid loosing my job :D
  packageConf.private = true;

  return packageConf;
}" > src/bigbrother/package.js

# Simply override the default license
mkdir src/bigbrother/assets
echo "
Copyright Big Brother inc. All rights reserved.
" > src/bigbrother/assets/LICENSE.md

Now, just create a new version of your package, publish it and add this specific behavior by adding the following property to your Big Brother's projects:

{
  "version": "1.0.0",
  "metapak": {
    "configs": ["bigbrother"]
  }
}

Note that the _common folder config cannot be disabled. That said you can only create specific configs and have no common behavior set at all. Keep common configs simple and very general to avoid having to change it too often.

Authors

• Nicolas Froidure

License

MIT