rerun-ci.yml

name: "Rerun CI"

on:
  workflow_run:
    workflows:
      - "Computer CI"
    types:
      - completed

permissions: {}

env:
  MAX_RERUNS: '2'
  RETRY_DELAY_SECONDS: '180'

jobs:
  decide-rerun-action:
    if: ${{ github.event.workflow_run.conclusion == 'failure' }}
    runs-on: ubuntu-latest
    outputs:
      action: ${{ steps.decision.outputs.action }}
    steps:
      - name: Decide rerun action
        id: decision
        env:
          WORKFLOW_NAME: ${{ github.event.workflow_run.name }}
          RUN_ID: ${{ github.event.workflow_run.id }}
          RUN_ATTEMPT: ${{ github.event.workflow_run.run_attempt }}
          EVENT_NAME: ${{ github.event.workflow_run.event }}
          HEAD_BRANCH: ${{ github.event.workflow_run.head_branch }}
        run: |
          set -euo pipefail

          action="skip"
          reason="unsupported event: $EVENT_NAME"

          if [[ "$EVENT_NAME" == "push" || "$EVENT_NAME" == "pull_request" ]]; then
            if (( RUN_ATTEMPT > MAX_RERUNS )); then
              reason="retry limit reached"
            else
              action="rerun"
              reason="within retry limit"
            fi
          fi

          {
            echo "action=$action"
            echo "reason=$reason"
          } >> "$GITHUB_OUTPUT"

          {
            echo "### Rerun CI decision"
            echo ""
            echo "- Workflow: $WORKFLOW_NAME"
            echo "- Source event: $EVENT_NAME"
            echo "- Head branch: $HEAD_BRANCH"
            echo "- Run ID: $RUN_ID"
            echo "- Current attempt: $RUN_ATTEMPT"
            echo "- Max automatic reruns: $MAX_RERUNS"
            echo "- Delay seconds: $RETRY_DELAY_SECONDS"
            echo "- Action: $action"
            echo "- Reason: $reason"
          } >> "$GITHUB_STEP_SUMMARY"

  rerun-failed-jobs:
    needs: decide-rerun-action
    if: needs.decide-rerun-action.outputs.action == 'rerun'
    permissions:
      actions: write
      contents: read
    runs-on: ubuntu-latest
    steps:
      - name: Wait before rerun
        run: |
          sleep "$RETRY_DELAY_SECONDS"

      - name: Check source branch freshness
        id: freshness
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          HEAD_REPOSITORY: ${{ github.event.workflow_run.head_repository.full_name }}
          HEAD_BRANCH: ${{ github.event.workflow_run.head_branch }}
          HEAD_SHA: ${{ github.event.workflow_run.head_sha }}
          WORKFLOW_NAME: ${{ github.event.workflow_run.name }}
          RUN_ID: ${{ github.event.workflow_run.id }}
        run: |
          set -euo pipefail

          action="rerun"
          latest_head_sha="$HEAD_SHA"
          reason="head unchanged"

          if [[ -z "$HEAD_REPOSITORY" || -z "$HEAD_BRANCH" || -z "$HEAD_SHA" ]]; then
            action="skip"
            reason="missing head repository metadata"
          else
            latest_head_sha="$(gh api "repos/$HEAD_REPOSITORY/commits" -f sha="$HEAD_BRANCH" -F per_page=1 --jq '.[0].sha' 2>/dev/null || true)"

            if [[ -z "$latest_head_sha" || "$latest_head_sha" == "null" ]]; then
              action="skip"
              reason="head branch no longer available"
            elif [[ "$latest_head_sha" != "$HEAD_SHA" ]]; then
              action="skip"
              reason="head moved to $latest_head_sha"
            fi
          fi

          {
            echo "action=$action"
            echo "latest_head_sha=$latest_head_sha"
            echo "reason=$reason"
          } >> "$GITHUB_OUTPUT"

          {
            echo "### Rerun CI freshness check"
            echo ""
            echo "- Workflow: $WORKFLOW_NAME"
            echo "- Run ID: $RUN_ID"
            echo "- Head repository: $HEAD_REPOSITORY"
            echo "- Head branch: $HEAD_BRANCH"
            echo "- Failed run head SHA: $HEAD_SHA"
            echo "- Current branch tip SHA: $latest_head_sha"
            echo "- Action: $action"
            echo "- Reason: $reason"
          } >> "$GITHUB_STEP_SUMMARY"

      - name: Rerun failed jobs
        if: steps.freshness.outputs.action == 'rerun'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GH_REPO: ${{ github.repository }}
        run: |
          gh run rerun ${{ github.event.workflow_run.id }} --failed