notify_on_failure.yml

name: Notification for master failure
on:
  workflow_run:
    workflows: [Build and Test]
    types: [completed]
    branches: [master]

jobs:
  on-failure:
    name: Send message to slack
    runs-on: ubuntu-latest
    if: ${{ github.event.workflow_run.conclusion == 'failure' }}
    steps:
      - name: Post to slack channel
        id: slack
        uses: slackapi/slack-github-action@v1.23.0
        env:
          SLACK_BOT_TOKEN: ${{ secrets.TAICHI_BOT_TOKEN }}
        with:
          # channel #build
          channel-id: 'C02BDNMG8MR'
          payload: |
            {
              "blocks": [
                {
                  "type": "header",
                  "text": {
                    "type": "plain_text",
                    "text": ":bbb: Master is on fire",
                    "emoji": true
                  }
                },
                {"type": "divider"},
                {
                  "type": "section",
                  "text": {
                    "type": "mrkdwn",
                    "text": ${{ toJSON(github.event.workflow_run.html_url) }}
                  }
                }
              ]
            }