A GitHub Action that offers an easy way to automatically add labels to opened PRs depending on their head and/or base branch. The branches can be specified directly or using patterns, such as feature/* or bugfix/*.

To use the PR Branch Labeler, you can add a YAML-based workflow file, e.g..github/workflows/pr-branch-labeler.yml, with the following content:

name: PR Branch Labeler

on: pull_request

jobs:
  label_prs:
    runs-on: ubuntu-latest
    steps:
    - name: Label PRs
      if: github.event.action == 'opened' # Only run the action when the PR was first opened
      uses: ffittschen/pr-branch-labeler@v1
      with:
        repo-token: ${{ secrets.GITHUB_TOKEN }}

Warning: if the Pull Requests submitted on your repository come from a fork, you must use the event pull_request_target instead of pull_request. This will grant write permissions to secrets.GITHUB_TOKEN. If you use pull_request, the secrets.GITHUB_TOKEN will have read-only permissions which does not work. See GitHub Action event pull_request_target reference.

Configure the PR Branch Labeler action by creating a .github/pr-branch-labeler.yml file, e.g. with the following:

# Apply label "feature" if head matches "feature/*"
feature:
  head: "feature/*"

# Apply label "bugfix" if head matches one of "bugfix/*" or "hotfix/*"
bugfix:
  head: ["bugfix/*", "hotfix/*"]

If only a head is specified, you can also use the shorthand notation. The following configuration is equivalent to the one above:

feature: "feature/*"
bugfix: ["bugfix/*", "hotfix/*"]

In case you want to assign labels if the PR has a specific base branch, you can specify it in the configuration as follows:

# Apply label "release" if base matches "release/*"
release:
  base: "release/*"

If you specify both, head and base, it will be seen as an AND condition:

# Apply label "🧩 Subtask" if head and base match "feature/*"
🧩 Subtask:
  head: "feature/*"
  base: "feature/*"

Note: If there are multiple rules matching one branch, all of the labels will be added to the PR. One example of this would be a configuration that contains the feature and subtask rules. If a new PR with head and base matching feature/* will be opened, the PR gets the labels feature AND 🧩 Subtask.