feat: add label filter to reduce scope of action

[tagoro9]

Thanks for this really cool action! I started to use it, but realized that I needed it to only run in PRs that had certain labels.

This PR adds support to specify a list of labels that a pull request must have to trigger the action. If the target PR doesn't have any of the specified labels, then the action is skipped.

[kentaro-m]

Hi, @tagoro9. Thank you for adding a nice new feature!
I checked this PR and add some comments.
Please check my comments and let me know if you have any questions.

[kentaro-m]

The action will only run if the PR has any of the specified labels

[IMO] On the other hand, I think there might be use cases not to run the action if adding specific labels to a pull request. Therefore I came up with an idea which labels can be set separately for include and exclude.

Also, add a property called filterLabels to clarify what the labels property is used for (e.g. skipKeywords: A list of keywords to be skipped the process that add reviewers if pull requests include it).

Suggest a configuration file format, such as:

filterLabels:
  # Run
  include:
    - my_label
    - another_label
  # Not Run
  exclude:
    - wip

What do you think of this suggestion of mine?

[tagoro9]

Thanks for your feedback! I think this makes sense. I'll update the code to support this

[kentaro-m]

[INFO] Label data added to the pull request may be available from a webhook payload. If this is available, codes for calling the API to fetch labels data can be removed.

auto-assign-action/src/handler.ts

Line 31 in 6c480d0

const { title, draft, user, number } = context.payload.pull_request

context.payload.pull_request.labels

GitHub Document:
https://developer.github.com/v3/activity/events/types/#pullrequestevent

[kentaro-m]

LGTM! Thanks for your changes.

[kentaro-m]

@tagoro9
This feature released as v1.1.0 🎉
https://github.com/kentaro-m/auto-assign-action/releases/tag/v1.1.0

It works with the following configuration file:

name: 'Auto Assign'
on: pull_request

jobs:
  add-reviews:
    runs-on: ubuntu-latest
    steps:
      - uses: kentaro-m/auto-assign-action@v1.1.0
        with:
          repo-token: "${{ secrets.GITHUB_TOKEN }}"