paths-ignore.yaml

# This is a reusable workflow to determine if the current change requires an E2E
# run.  This is required because using [paths-ignored] directly means the whole
# workflow is skipped, but that means that it doesn't count as having run a
# required workflow.

# Usage:
#   jobs:
#     check-paths:
#        uses: ./.github/workflows/actions/paths-ignore.yaml
#     do_thing:
#        if: jobs.check-paths.outputs.should-run == 'true'
#        # Unfortunately, a string comparison is required.

name: Check for ignored paths

on:
  workflow_call:
    inputs:
      paths-ignore-globs:
        description: >
          Paths to ignore.  Should glob patterns (as a git pathspec glob), one
          per line.  See
          https://git-scm.com/docs/gitglossary#Documentation/gitglossary.txt-glob
        type: string
        default: |
          .github/actions/spelling/**
          bats/**
          docs/**
          **.md
    outputs:
      should-run:
        description: Whether other steps should run.
        value: ${{ jobs.check.outputs.should-run }}

permissions:
  contents: read

jobs:
  check:
    runs-on: ubuntu-latest
    steps:
    - name: Set baseline result
      run: echo "SHOULD_RUN=true" >> "$GITHUB_ENV"
    - name: Determine paths to ignore
      if: github.event_name == 'pull_request'
      run: |
        PATHS_IGNORE="PATHS_IGNORE="
        while read -r line; do
          if [[ -n $line ]]; then
            PATHS_IGNORE="${PATHS_IGNORE} :!/${line}"
          fi
        done <<< "$INPUT"
        echo "$PATHS_IGNORE"
        echo "$PATHS_IGNORE" >> "$GITHUB_ENV"
      env:
        INPUT: ${{ inputs.paths-ignore-globs }}
    - uses: actions/checkout@v4
      if: github.event_name == 'pull_request'
      with:
        fetch-depth: 0
        persist-credentials: false
    - name: Check for differences
      if: github.event_name == 'pull_request'
      run: |
        MERGE_BASE=$(git merge-base $BASE $HEAD)
        diff="$(git diff --name-only $MERGE_BASE $HEAD -- $PATHS_IGNORE)"
        if [[ -z "$diff" ]]; then
          echo "No modified files found."
          echo "SHOULD_RUN=false" >> "$GITHUB_ENV"
        else
          printf "Modified files:\n%s\n" "$diff"
        fi
      env:
        BASE: ${{ github.event.pull_request.base.sha }}
        HEAD: ${{ github.event.pull_request.head.sha }}
    - name: Set final output
      id: result
      run: echo "should-run=$SHOULD_RUN" >> "$GITHUB_OUTPUT"
    outputs:
      should-run: ${{ steps.result.outputs.should-run }}