action.yaml

---
name: Job Context
description: Provides additional context for the currently running job
branding:
  icon: box
  color: black
outputs:
  name:
    description: The rendered job name.
    value: ${{ steps.render.outputs.name }}
  id:
    description: >-
      The numeric job ID as used by the GitHub API. Not be be confused with the workflow
      job key `github.job`.
    value: ${{ steps.job-api.outputs.id }}
runs:
  using: composite
  steps:
    # In order to determine the job name we'll extract the non-rendered job name from the workflow and then evaulate
    # any expressions contained within. Using `action/checkout` requires that we set the path under `$GITHUB_WORSPACE`.
    - uses: actions/checkout@v4
      id: checkout
      with:
        ref: ${{ github.workflow_sha }}
        path: ${{ format('{0}/.job-context-repo', github.workspace) }}
    - id: workflow
      shell: bash
      run: |
        # Workflow job name template
        [[ "$RUNNER_DEBUG" -eq 1 ]] && set -x
        set -euo pipefail

        # e.g. octocat/hello-world/.github/workflows/my-workflow.yml@refs/heads/my_branch -> .github/workflows/my-workflow.yml
        workflow_path="$(echo "${workflow_ref%@*}" | cut -d/ -f3-)"
        job_name_template="$(job_key="${job_key}" yq '.jobs[env(job_key)] | select(has("name")).name | select(. != null)' "${repo_path}/${workflow_path:?}")"
        echo "name-template=${job_name_template}" | tee -a "$GITHUB_OUTPUT"
      env:
        repo_path: ${{ format('{0}/.job-context-repo', github.workspace) }}
        workflow_ref: ${{ github.workflow_ref }}
        job_key: ${{ github.job }}  # User supplied job key cannot be allowed as we cannot properly render `matrix` expressions later
    - id: render
      shell: bash
      run: |
        # Render job name
        [[ "$RUNNER_DEBUG" -eq 1 ]] && set -x
        set -euo pipefail

        # Determine if job name contains GitHub expressions. As GitHub expressions must be
        # closed we can just check for the opening sequence.
        if grep -qE '\$\{\{' <<<"${job_name_template}"; then
            # Convert GHA expressions into jq Bash expressions. Converts `null` results into `""` to match GHA behavior.
            # e.g. `{{ matrix.demo.version }}` -> `$(jq -r '.demo.version | select(type != "null")' <<<"${matrix_json:?}")`
            job_name_expr="$(perl -pe 's/\$\{\{\s*([a-z]+)\.([a-z0-9._-]+)\s*}}/\$(jq -r --arg p "\2" '\''getpath(\$p | split(".")) | select(type != "null")'\'' <<<"\${\1_json:?}")/g' <<<"${job_name_template}")"
            job_name="$(eval "echo \"${job_name_expr}\"")"
        else
            job_name="${job_name_template}"
            if [ -z "${job_name}" ]; then
                job_name="${job_key:?}"
            fi

            # GitHub adds job matrix values to job names which do not contain expressions.
            matrix_values="$(jq -r '[.. | select(type != "object")] | join(", ")' <<<"${matrix_json}")"
            if [[ -n "${matrix_values}" ]]; then
                job_name="${job_name:?} (${matrix_values})"
            fi
        fi
        echo "name=${job_name:?}" | tee -a "$GITHUB_OUTPUT"
      env:
        job_name_template: ${{ steps.workflow.outputs.name-template }}
        job_key: ${{ github.job }}

        # `jobs.<job_id>.name` can use the contexts: [github, needs, strategy, matrix, vars, inputs]. No functions are allowed.
        # https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/contexts#context-availability
        github_json: ${{ toJSON(github) }}
        # needs_json: ${{ toJSON(needs) }}
        strategy_json: ${{ toJSON(strategy) }}
        matrix_json: ${{ toJSON(matrix) }}
        # vars_json: ${{ toJSON(vars) }}
        # inputs_json: ${{ toJSON(inputs) }}

    # With the rendered job name we can use the GitHub API to fetch the job ID from the API
    # as long as the job name is distinct within the workflow.
    - id: job-api
      shell: bash
      run: |
        # Fetch job ID
        [[ "$RUNNER_DEBUG" -eq 1 ]] && set -x
        set -euo pipefail

        # https://docs.github.com/en/rest/actions/workflow-runs?apiVersion=2022-11-28#get-a-workflow-run-attempt
        jobs="$(gh api -X GET "/repos/{owner}/{repo}/actions/runs/${run_id:?}/attempts/${run_attempt:?}/jobs")"
        job_ids="$(jq -c --arg name "$job_name" '[.jobs[] | select(.name == $name) | .id]' <<<"${jobs}")"

        if [[ $(jq length <<<"${job_ids}") -eq 1 ]]; then
            echo "id=$(jq 'first' <<<"${job_ids}")" | tee -a "$GITHUB_OUTPUT"
        else
            echo "ERROR: Unable to determine job ID. The job name \"${job_name:?}\" is not unique within the workflow." >&2
            exit 1
        fi
      env:
        GH_TOKEN: ${{ github.token }}
        GH_REPO: ${{ github.repository }}
        run_id: ${{ github.run_id }}
        run_attempt: ${{ github.run_attempt }}
        job_name: ${{ steps.render.outputs.name }}
    - name: Cleanup
      if: ${{ always() && steps.checkout.output == 'success' }}
      shell: bash
      run: rm -rf "${repo_path:?}"
      env:
        repo_path: ${{ format('{0}/.job-context-repo', github.workspace) }}