action.yml

name: upstream_sync

description: >
  Automatically sync branch from upstream repository.

inputs:
  upstreamRepo:
    description: Upstream repository slug (owner/repo).
    default: The-OpenROAD-Project/OpenROAD
  upstreamBranch:
    description: Upstream branch name to update.
    default: master
  force:
    description: Use a force push.
    default: false
  syncTags:
    description: >
      Also fetch and force-push tags from upstream. Off by default. Turn on
      for mirrors where an independent process (e.g. a scheduled tag-creation
      workflow) may also run on the upstream repo, so this mirror should
      always hold the exact same tag objects rather than creating its own.
    default: false
  deployKey:
    description: SSH Private "deploy key" which has write access.
    required: true

runs:
  using: composite

  steps:

  - name: Updating '${{ inputs.upstreamBranch }}' from ${{ inputs.upstreamRepo }}
    env:
      FORCE: ${{ inputs.force }}
      SYNC_TAGS: ${{ inputs.syncTags }}
    shell: bash
    run: |
      # Configure ssh to ignore host key checking.
      mkdir -p ~/.ssh
      chmod 700 ~/.ssh
      echo "::group::Existing ssh config file"
      cat ~/.ssh/config || true
      echo "::endgroup::"
      cat > ~/.ssh/config << EOF
      Host *
        StrictHostKeyChecking no
        UserKnownHostsFile /dev/null
      EOF
      # Figure out if we should do a force push
      export GIT_ARGS=''
      if [[ x$FORCE = 'xtrue' ]]; then
        export GIT_ARGS=--force
      fi
      # Clone a blobless repository and don't bother checking it out.
      echo "::group::Clone repo"
      rm -rf repo
      git clone \
        --filter=blob:none \
        --no-tags \
        --no-checkout \
        --origin upstream \
        --branch ${{ inputs.upstreamBranch }} \
        --verbose \
        https://github.com/${{ inputs.upstreamRepo }}.git \
        repo
      cd repo
      echo "::endgroup::"
      # Start ssh agent and add deploy key.
      eval $(ssh-agent -s)
      ssh-add - <<< "${{ inputs.deployKey }}"
      # Add local repository and push to it.
      echo "::group::Push repo"
      git remote add origin git+ssh://git@github.com/${{ github.repository }}.git
      git push origin $GIT_ARGS --verbose upstream/${{ inputs.upstreamBranch }}:${{ inputs.upstreamBranch }}
      echo "::endgroup::"
      # Mirror tags exactly rather than letting this repo create its own
      # (e.g. via a separately-scheduled tag-creation workflow), which would
      # produce a different tag object for the same commit and break plain
      # `git fetch` between the two remotes ("would clobber existing tag").
      if [[ x$SYNC_TAGS = 'xtrue' ]]; then
        echo "::group::Sync tags"
        git fetch upstream --tags --verbose
        git push origin --force --tags --verbose
        echo "::endgroup::"
      fi
      kill $SSH_AGENT_PID