Cron pull request labeler is an extension of actions/labeler which triages PRs based on the paths that are modified in the PR using a periodic cron job.

The actions/labeler GitHub Action runs into the following issue (further described in actions/labeler#12) when the check runs on a pull request originating from a forked repository:

##[error] HttpError: Resource not accessible by integration
##[error] Resource not accessible by integration
##[error] Node run failed with exit code 1

This is a fairly restrictive limitation in the GitHub Pull Request Workflow which many open source projects follow.

This project circumvents this limitation by running the GitHub Action as a cron job on the target repository. The cron job continuously monitors the pull requests of the target repository and adds the appropriate labels in a rate limiting aware manner with pagination support. The idea is that if this action is run often enough it will keep labeling the most recently updated pull requests, and eventually all pull requests will have been labeled.

Create a .github/labeler.yml file with a list of labels and minimatch globs to match to apply the label.

The key is the name of the label in your repository that you want to add (eg: "merge conflict", "needs-updating") and the value is the path (glob) of the changed files (eg: src/**/*, tests/*.spec.js)

# Add 'label1' to any changes within 'example' folder or any subfolders
label1:
  - example/**/*

# Add 'label2' to any file changes within 'example2' folder
label2: example2/*

# Add 'repo' label to any root file changes
repo:
  - ./*
  
# Add '@domain/core' label to any change within the 'core' package
@domain/core:
  - package/core/*
  - package/core/**/*

# Add 'test' label to any change to *.spec.js files within the source dir
test:
  - src/**/*.spec.js

Create a workflow (eg: .github/workflows/labeler.yml see Creating a Workflow file) to utilize the labeler action running every 10 minutes:

name: "Pull Request Labeler"
on:
  schedule:
  - cron: "*/10 * * * *"

jobs:
  triage:
    runs-on: ubuntu-latest
    steps:
    - uses: fjeremic/cron-labeler@0.2.0
      with:
        repo-token: ${{ secrets.GITHUB_TOKEN }}

Note: This grants access to the GITHUB_TOKEN so the action can make calls to GitHub's rest API.