send_tweet.yaml

name: send a tweet if PR is merged (and there is a tweet to be sent)

on:
  pull_request:
    types: [closed]
env:
  TWEET_KEYWORD: '__[tweet]__'
  TWEET_SENT_KEYWORD: '__[tweet sent]__'
jobs:
  publish_tweet:
    runs-on: ubuntu-latest
    if: github.event.pull_request.merged
    steps:
    - name: find the tweet comment matching the keyword env.TWEET_KEYWORD
      uses: peter-evans/find-comment@v1
      id: fc
      with:
        issue-number: ${{github.event.pull_request.number}}
        comment-author: github-actions[bot]
        body-includes: ${{env.TWEET_KEYWORD}}
    - name: if tweet CI comment is found, extract tweet from comment body
      id: extract-tweet
      if: ${{steps.fc.outputs.comment-id != null}}
      env: 
        COMMENT_BODY: ${{steps.fc.outputs.comment-body}}
      run: |
        body=$(echo "$COMMENT_BODY" | sed '1d' | sed 's/> //')
        # escape file content to preserve new lines
        # (see example in https://github.com/peter-evans/create-or-update-comment)
        body="${body//'%'/'%25'}"
        body="${body//$'\n'/'%0A'}"
        body="${body//$'\r'/'%0D'}"
        echo ::set-output name=body::$body
    - name: tweet the message
      if: ${{steps.fc.outputs.comment-id != null}}
      uses: ethomson/send-tweet-action@v1
      with:
        status: ${{steps.extract-tweet.outputs.body}}
        consumer-key: ${{secrets.TWITTER_API_KEY}}
        consumer-secret: ${{secrets.TWITTER_API_SECRET_KEY}}
        access-token: ${{secrets.TWITTER_ACCESS_TOKEN}}
        access-token-secret: ${{secrets.TWITTER_ACCESS_TOKEN_SECRET}}
    - name: clear tweet keyword
      if: ${{steps.fc.outputs.comment-id != null}}
      uses: peter-evans/create-or-update-comment@v1
      with:
        comment-id: ${{steps.fc.outputs.comment-id}}
        edit-mode: replace
        body: ${{env.TWEET_SENT_KEYWORD}}