Verify Pull Request Label Action

This action will verify if a pull request has at least one label from a set of valid labels. The set of valid valid labels is defined by the user and passed as an input argument.

If the pull request does not contain a label from the set of valid labels, then the action will create a pull request review using the event REQUEST_CHANGES. On the other hand, if a valid label is present in the pull request, the action will create a pull request review using the event APPROVE instead. In both of these cases the exit code will be 0, and the GitHub check will success.

This actions uses the pull request workflow to prevent the merging of a pull request without a valid label, instead of the status of the GitHub checks. The reason for this is that GitHub workflows will run independent checks for different trigger conditions, instead of grouping them together. For example, consider that action is triggered by pull_request's types opened and labeled, then if a pull request is opened without adding a valid label at the time of open the pull request, then that will trigger a check that should failed; however, adding later a valid label to the pull request will just trigger a new check which should succeed, but the first check will remain in the failed state, and the pull request merge will be blocked (if the option Require status checks to pass before merging is enabled in the repository).

Instead, consider the same example, the action is triggered by pull_request's types opened and labeled, then if a pull request is opened without adding a valid label at the time of open the pull request, then that will trigger a check that will succeed, but will crate a pull request review, requesting for changes. The pull request review will prevent the merging of the pull request (if the option Require pull request reviews before merging is enabled in the repository) in this case. Adding a valid label to the repository will then trigger a new action which will succeed as well, but in this case it will create a new pull request review, approving the pull request. After this the pull request can be merge.

Note: if you want to use the Require pull request reviews before merging to require reviews approval before merging pull request, then you need to increase the number of Required approving reviewers by one, as this check will do an approval when a valid label is present. So, for example, if you want at least one reviewer approval, the set this value to 2.

Inputs

github-token

Required The GitHub token.

valid-labels

Required A list of valid labels. It must be a quoted string, with label separated by colons. For example: 'bug, enhancement'

post-review

Non-Required Post approve review after checking valid labels

post-comment

Non-Required Comment to post in PR after checking valid labels fails.

Example usage

In your workflow YAML file add this step:

uses: actions/[email protected]
with:
    github-token: '${{ secrets.GITHUB_TOKEN }}'
    valid-labels: 'bug, enhancement'

or with approve review:

uses: actions/[email protected]
with:
    github-token: '${{ secrets.GITHUB_TOKEN }}'
    valid-labels: 'bug, enhancement'
    post-review: true
    post-comment: "example comment on failure"
    ```


and trigger it with:
```yaml
on:
  pull_request:
   types: [labeled, unlabeled]