changelog-existence.yml

# **what?**
# Checks that a file has been committed under the /.changes directory, 
# within the 'unreleased' directory or `unreleased_dir`,
# as a new or modified CHANGELOG entry.  Cannot check for a specific filename as
# it is dynamically generated by change type and timestamp.
#

# **why?**
# Ensure code change gets reflected in the CHANGELOG.

# **when?**
# This will run when called in a workflow.

# Example Usage including required permissions

# on:
#   pull_request_target:
#     types: [opened, reopened, labeled, unlabeled, synchronize]
#
# permissions:
#   contents: read
#   pull-requests: write
#
# name: Check Changelog Entry
# jobs:
#   changelog:
#     uses: dbt-labs/actions/.github/workflows/changelog-check.yml@main
#    with:
#      changelog_comment: 'Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see [the contributing guide](https://github.com/dbt-labs/dbt-core/blob/main/CONTRIBUTING.md#adding-changelog-entry).'
#      skip_label: 'Skip Changelog'
#      unreleased_dir: 'unreleased'
#    secrets: inherit # this is only acceptable because we own the action we're calling
#

name: Check Changelog Entry Exists

on:
  workflow_call:
    inputs:
      changelog_comment:
        description: The comment text when no changelog is found
        type: string
        required: true
      skip_label:
        description: Label on the PR that indicates CHANGELOGs are not required.
        type: string
        required: true
      unreleased_dir:
        description: The subdirectory unreleased changelogs are expected to be found. By default, this is 'unreleased'.
        type: string
        required: false
        default: 'unreleased'

permissions:
  contents: read
  pull-requests: write

jobs:
  changelog_existence:
    name: Check if Changelog Exists
    if: ${{ !contains(github.event.pull_request.labels.*.name, inputs.skip_label) }}
    runs-on: ubuntu-latest

    steps:
      - name: "[DEBUG] - Print Inputs"
        shell: bash
        id: echo_inputs
        run: |
          echo "all variables defined as inputs"
          echo "inputs.changelog_comment:    ${{ inputs.changelog_comment }}"
          echo "inputs.skip_label:           ${{ inputs.skip_label }}"
          echo "inputs.unreleased_dir:       ${{ inputs.unreleased_dir }}"

      - name: Check if changelog file was added
        # https://github.com/marketplace/actions/paths-changes-filter
        # For each filter, it sets output variable named by the filter to the text:
        #  'true' - if any of changed files matches any of filter rules
        #  'false' - if none of changed files matches any of filter rules
        uses: dorny/paths-filter@v3
        id: changelog_check
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          filters: |
            exists:
              - added|modified: '.changes/${{ inputs.unreleased_dir }}/**.yaml'

      # this step uses the read permission from the GITHUB_TOKEN it inherits
      - name: Check for comment
        if: steps.changelog_check.outputs.exists == 'false'
        uses: peter-evans/find-comment@v3
        id: changelog_comment
        with:
          issue-number: ${{ github.event.pull_request.number }}
          comment-author: "github-actions[bot]"
          body-includes: ${{ inputs.changelog_comment }}

      - name: Set if comment already exists
        if: steps.changelog_check.outputs.exists == 'false'
        shell: bash
        id: comment_check
        run: |
          if [ '${{ steps.changelog_comment.outputs.comment-body }}' = '' ]; then
            echo "exists=false" >> $GITHUB_OUTPUT
            echo "Comment does not exist for this PR"
          else
            echo "exists=true" >> $GITHUB_OUTPUT
            echo "Comment already exists for this PR"
          fi

      # this step uses the write permission on the PR from the GITHUB_TOKEN it inherits
      - name: Create PR comment if changelog entry is missing, required, and does not exist
        if: |
          steps.changelog_check.outputs.exists == 'false' &&
          steps.comment_check.outputs.exists == 'false'
        run: |
          gh issue comment ${{ github.event.pull_request.number }} --repo ${{ github.repository }} --body "${{ inputs.changelog_comment }}"
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Fail job if changelog entry is missing and required
        if: steps.changelog_check.outputs.exists == 'false'
        uses: actions/github-script@v7
        with:
          script: core.setFailed('Changelog entry required to merge.')