ci: add commitlint for conventional commits

.DS_Store

.idea

*.log

tmp/

node_modules/

    - gem install --no-document rspec

  script:

    - rspec test/rspec

commitlint:

  stage: test

  image: node:12

  needs: []

  before_script:

    - npm install

  script:

    - npx --quiet commitlint --from="$CI_MERGE_REQUEST_DIFF_BASE_SHA" --help-url 'https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image#git-commit-guidelines'

  rules:

    - if: "$CI_MERGE_REQUEST_EVENT_TYPE != 'merge_train' && $CI_MERGE_REQUEST_DIFF_BASE_SHA"

This project uses [Semantic Versioning](https://semver.org). We use commit

messages to automatically determine the version bumps, so they should adhere to

the conventions of [Conventional Commits (v1.0.0-beta.2)](https://www.conventionalcommits.org/en/v1.0.0-beta.2/).

the conventions of [Conventional Commits (v1.0.0)](https://www.conventionalcommits.org/en/v1.0.0).

### TL;DR

- Commit title starting with `feat: ` trigger a minor version bump

- Commit body contains `BREAKING CHANGE: ` trigger a major version bump. This can be part of commits of any _type_.

### Tip: Test commit messages locally

Testing the commit message locally can speed up the iteration cycle. It can be configured as follows:

``` sh

# install dev dependencies, if necessary

npm install

# usage

npx commitlint --from=master # if targeting latest

npx commitlint --from=1.x # if targeting 1.x stable

```

### Tip: Use a git hook with commitlint

To save yourself the manual step of testing the commit message, you can use a commit hook.

At the root of this project, add `.git/hooks/commit-msg` with the following contents:

``` sh

#!/bin/sh

npx commitlint --edit

```

Then, run `chmod +x .git/hooks/commit-msg` to make it executable.

## Automatic versioning

Each push to `master` triggers a [`semantic-release`](https://semantic-release.gitbook.io/semantic-release/)

module.exports = {

    extends: ['@commitlint/config-conventional'],

};