📦 automated package publishing
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What is semantic-release about?

It fully automates your package's releases. It will determine not only which version to release, but also when – all without you wasting cognitive resources on it.

It is fully integrated into the npm lifecycle, so all you need to do is to configure your CI to regularly npm publish (i.e. for every commit).

It removes human decisions and emotions from version numbers and releases – suddenly, strictly following the SemVer spec isn't a problem anymore.


How does it work?

Meaningful conventions. Instead of dumping lols into our commit messages, we can take some time to think about what we changed in the codebase and write it down. Following formalized conventions it this then possible to not only generate a helpful changelog, but to determine whether a new version should be released.

This module ships with the AngularJS Commit Message Conventions, but you can define your own.

The prepublish step

Before npm actually gets to publish a new version semantic-release's prepublish step does the following:

  • Extract all commits since the last version was published
  • Determine the release type (major|minor|patch) or abort if nothing relevant changed
  • Increase the version number accordingly

The publish step

npm does its thing.

The postpublish step

After npm published the new version the postpublish step does this:

  • Generate release notes
  • Create a new GitHub Release (including a git tag) with the release notes

Note: The default release notes are a changelog that is generated from git metadata, using the AngularJS commit conventions. You can specify your own release note generator.

Note: This is tied to GitHub, feel free to send PRs for other services.

Note: semantic-release works around a limitation in npm's prepublish step. Once a version is published it prints a "Could not pack" error that you can safely ignore npm/npm#7118.

How you can set it up


First of all you need to install semantic-release and save it as a devDependency.

npm install --save-dev semantic-release
# Btw, if you're feeling lazy you can just type this – it's the same thing.
npm i -D semantic-release


./node_modules/.bin/semantic-release setup

What this does:


The setup command configures scripts inside the package.json:

"scripts": {
  "prepublish": "semantic-release pre",
  "postpublish": "semantic-release post"

Note: If you have already configured scripts for prepublish or postpublish they're just executed one after another. For example: "npm run babelify && semantic-release pre".


It would be preferable not to have a version field in the package.json at all, but due to an npm limitation it is required to have a not yet published version in there npm/npm#7118. Because of this the version gets changed to "0.0.0-semantically-released" until npm hopefully removes its limitations.


If you haven't defined your GitHub repository in the package.jsons repository field the remote origin's repository is used.

CI Server

Inside your .travis.yml:

language: node_js
- iojs-v1
# If you have a more sophisticated build with multiple jobs you should have a look at
# https://github.com/dmakhno/travis_after_all which is also configured for this
# package. (Check the .travis.yml)
sudo: false
  - node_modules
  email: false
# See https://github.com/boennemann/semantic-release/issues/18
- npm config set spin false --global
  # Get your token here: https://github.com/settings/tokens/new
  # Grant the token repo/public_repo scope (all others can be deselected)
  # You should encrypt this:
  # `travis encrypt GH_TOKEN=<token> --add`
  global: GH_TOKEN=<github-access-token-with-access-to-your-repo>
  provider: npm
  email: <your-npm-mail@example.com>
  # Very important. Don't forget this one.
  skip_cleanup: true
  # Travis currently only supports the old auth key format.
  # Do `echo -n "<username>:<password>" | base64` to get it.
  # You should encrypt this:
  # `travis encrypt $(echo -n "<username>:<password>" | base64) --add deploy.api_key`
  api_key: <npm-api-key>
    branch: master
    repo: <user>/<repo>

Note: This isn't tied to a specific service, but example configuration is provided for Travis CI. Feel free to contribute configuration for other servers or services.

Note: You should [encrypt](http://docs.travis-ci.com/user/environment-variables/#sts=Secure Variables) your api keys and tokens.

Note: Your CI environment has to export CI=true in order for semantic-release not to automatically perform a dry run. Travis CI does this by default.

Note: It is crucial that your CI server also fetches all tags when checking out your repository. Travis CI does this by default.


I think you might frequently ask questions like these

Why is the package.json's version not updated in my repository?

The npm docs even state:

The most important things in your package.json are the name and version fields. Those are actually required, and your package won't install without them. -- npm docs

While this entirely true the version number doesn't have to be checked into source control. semantic-release takes care of the version field right before npm publish uses it – and this is the only point where it really is required.

Is there a way to preview which version would currently get published?

If you're running npm publish locally semantic-release automatically performs a dry run. This does log the version that would currently get published, but only if you git fetch --tags before.

Can I run this on my own machine rather than on a CI server?

Of course you can, but this doesn't necessarly mean you should. Running your tests on an independent machine before releasing software is a crucial part of this workflow. Also it is a pain to set this up locally, with GitHub tokens lying around and everything. That said, you can either set the environment variable CI=true, or run the scripts with --debug=false explicitly. Don't forget to export GH_TOKEN=your_token as well.

Can I manually trigger the release of a specific version?

You can trigger a release by pushing to your repository. You deliberately can not trigger a specific version release, because this is the whole point of semantic-release. Start your packages with 1.0.0 and semver on.

Note: The default commit message conventions do not support pre-release flags, but you can build this in yourself using custom analyzers.

How do I get back to good ol' npm publish?

npm offers the --ignore-scripts flag. Doing npm publish --ignore-scripts doesn't execute the prepublish and postpublish scripts.

Is it really a good idea to release on every push?

It is indeed a great idea because it forces you to follow best practices. If you don't feel comfortable making every passing feature or fix on your master branch addressable via npm you might not treat your master right. Have a look at branch workflows. If you still think you should have control over the exact point in time of your release, e.g. because you are following a release schedule, configure your CI server to release only on the production/deploy/release branch and push your code there in certain intervals.

Why should I trust semantic-release with my releases? What if it breaks?

semantic-release has a full integration-test suite that tests actual npm publishes and actual GitHub Releases (with private registry/API) on node.js ^0.10, ^0.12 and io.js ^1, ^2. A new version won't get published if it doesn't pass on all these engines.


MIT License 2015 © Stephan Bönnemann and contributors