action.yaml

---
name: Initialize Pantsbuild Environment
description: |
  Install pants and its dependencies and prepare pants caches.

inputs:
  pants-python-version:
    required: false
    default: '3.9'
  base-branch:
    required: false
    default: main
  gha-cache-key:
    required: true
    # use this for matrix.python-version or similar
  pants-ci-config:
    required: false
    default: pants.ci.toml
    # set to empty string to disable

runs:
  using: "composite"
  steps:
    - name: 'Set up Python for Pants (${{ inputs.pants-python-version }})'
      uses: actions/setup-python@v2
      with:
        python-version: '${{ inputs.pants-python-version }}'

    - name: Get Pants version
      id: pants_version
      shell: bash
      run: |
        # Capture the "pants_version = " line from config.
        PANTS_VERSION=$(grep -r '^pants_version\s*=' pants.toml)
        echo "::set-output name=pants_version::$PANTS_VERSION"

    - name: Cache Pants Setup (${{ steps.pants_version.outputs.pants_version }}-py${{ inputs.pants-python-version }})
      id: cache-pants-setup
      uses: actions/cache@v2
      with:
        path: |
          ~/.cache/pants/setup
        key: pants-setup-${{ runner.os }}-${{ steps.pants_version.outputs.pants_version }}-py${{ inputs.pants-python-version }}

    # Looking up the commit allows us to use the cache
    # from the latest commit on the base branch.
    - name: Get Pants Cache Commit (base branch commit to pull cache from)
      id: pants-cache-commit
      shell: bash
      # we could use this, but only if fetch-depth goes back far enough
      # COMMIT=$(git merge-base ${GITHUB_BASE_REF:-${{ inputs.base-branch }}} HEAD | head -n1)
      run: |
        CACHECOMMIT=$(
          gh api -H "Accept: application/vnd.github+json" \
          '/repos/${{ github.repository }}/commits?per_page=1&sha=${{ inputs.base-branch }}' \
          -q '.[].sha'
        )
        echo "::set-output name=CACHECOMMIT::${CACHECOMMIT}"
      env:
        GH_TOKEN: ${{ github.token }}

    - name: Cache Pants Named Caches (${{ inputs.gha-cache-key }})
      uses: actions/cache@v2
      id: cache-pants-named-caches
      with:
        path: |
          ~/.cache/pants/named_caches
        key: pants-named-caches-${{ runner.os }}-${{ inputs.gha-cache-key }}-${{ github.sha }}
        restore-keys: |
          pants-named-caches-${{ runner.os }}-${{ inputs.gha-cache-key }}-${{ steps.pants-cache-commit.outputs.CACHECOMMIT }}
          pants-named-caches-${{ runner.os }}-${{ inputs.gha-cache-key }}-

    # TODO: handle projects that use remote caching
    # see https://www.pantsbuild.org/docs/remote-caching
    - name: Cache Pants LMDB Store (${{ inputs.gha-cache-key }})
      uses: actions/cache@v2
      id: cache-pants-lmdb-store
      with:
        path: |
          ~/.cache/pants/lmdb_store
        key: pants-lmdb-store-${{ runner.os }}-pants-${{ inputs.gha-cache-key }}-${{ github.sha }}
        restore-keys: |
          pants-lmdb-store-${{ runner.os }}-${{ inputs.gha-cache-key }}-${{ steps.pants-cache-commit.outputs.CACHECOMMIT }}
          pants-lmdb-store-${{ runner.os }}-${{ inputs.gha-cache-key }}-

    # Adding env vars to ${GITHUB_ENV} makes the vars show up for all subsequent steps
    # in the workflow (in the workflow that uses this composite action).
    # https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-environment-variable
    - name: Tell pants to use CI config
      if: ${{ inputs.pants-ci-config != '' }}
      shell: bash
      run: |
        echo "PANTS_CONFIG_FILES=${{ inputs.pants-ci-config }}" >> ${GITHUB_ENV}

    - name: Bootstrap Pants
      shell: bash
      run: |
        ./pants --version