# Pull Request Labeler

Pull request labeler triages PRs based on the paths that are modified in the PR.

Note that only pull requests being opened from the same repository can be labeled.  This action will not currently work for pull requests from forks -- like is common in open source projects -- because the token for forked pull request workflows does not have write permissions.

## Usage

### Create `.github/labeler.yml`

Create a `.github/labeler.yml` file with a list of labels and [minimatch](https://github.com/isaacs/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`) or a match object.

#### Match Object

For more control over matching, you can provide a match object instead of a simple path glob. The match object is defined as:

```yml
- any: ['list', 'of', 'globs']
  all: ['list', 'of', 'globs']
```

One or both fields can be provided for fine-grained matching. Unlike the top-level list, the list of path globs provided to `any` and `all` must ALL match against a path for the label to be applied.

The fields are defined as follows:
* `any`: match ALL globs against ANY changed path
* `all`: match ALL globs against ALL changed paths

A simple path glob is the equivalent to `any: ['glob']`. More specifically, the following two configurations are equivalent:
```yml
label1:
- example1/*
```
and
```yml
label1:
- any: ['example1/*']
```

From a boolean logic perspective, top-level match objects are `OR`-ed together and indvidual match rules within an object are `AND`-ed. Combined with `!` negation, you can write complex matching rules.

#### Basic Examples

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

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

#### Common Examples

```yml
# 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

# Add 'source' label to any change to src files within the source dir EXCEPT for the docs sub-folder
source:
- any: ['src/**/*', '!src/docs/*']

# Add 'frontend` label to any change to *.js files as long as the `main.js` hasn't changed
frontend:
- any: ['src/**/*.js']
  all: ['!src/main.js']
```

### Create Workflow

Create a workflow (eg: `.github/workflows/labeler.yml` see [Creating a Workflow file](https://help.github.com/en/articles/configuring-a-workflow#creating-a-workflow-file)) to utilize the labeler action with content:

```
name: "Pull Request Labeler"
on:
- pull_request

jobs:
  triage:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/labeler@v2
      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_