Sending GitHub Action Results to Slack Channel

Sending data into Slack using slack-send.

slack-send

This post discusses practical guide for sending data to Slack via a Slack Incoming Webhook URL. The reason we prefer webhook approach is to preserve the privacy of team member. The chatbot invite approach potentially allow all Slack member to touch a private app of an individual

1. Follow the setup

2. Add slack-notification job and a trigger in the last CI/CD job:

   ---
   name: My CI/CD
   
   jobs:
     the-last-job:
       name: The last CI/CD job in workflow
       outputs:
         outcome: ${{ job.status }}
       continue-on-error: true
       runs-on: ubuntu-latest
       steps:
         ...
   
     slack-notification:
       name: Send Slack Notification
       if: ${{ always() }}
       needs: the-last-job
       uses: QubitPi/hashicorp-aws/.github/workflows/slack-notification.yml@master
       with:
         job-status: ${{ needs.the-last-job.outputs.outcome }}
       secrets:
         slack-webhook-url: ${{ secrets.SLACK_WEBHOOK_URL }}
   info

   Note the key block in the-last-job:

   outputs:
     outcome: ${{ job.status }}
   continue-on-error: true

Multi-Terminal-Job Configuration

The config above applies to the case with a single last job. We call this job "terminal job". The configuration becomes a little different when there are multiple terminal jobs such as the one workflow in the figure below:

In this case we change the job-status input of slack-notification:

---
name: My CI/CD

jobs:
  terminal-job-a:
    name: Terminal Job A
    outputs:
      outcome: ${{ job.status }}
    continue-on-error: true
    runs-on: ubuntu-latest
    steps:
      ...

  terminal-job-b:
    name: Terminal Job B
    outputs:
      outcome: ${{ job.status }}
    continue-on-error: true
    runs-on: ubuntu-latest
    steps:
      ...

  slack-notification:
    name: Send Slack Notification
    if: ${{ always() }}
    needs: [terminal-job-a, terminal-job-b]
    uses: QubitPi/hashicorp-aws/.github/workflows/slack-notification.yml@master
    with:
      job-status: ${{ (needs.terminal-job-a.outputs.outcome == 'success' && needs.terminal-job-b.outputs.outcome == 'success') && 'success' || 'failure' }}
    secrets:
      slack-webhook-url: ${{ secrets.SLACK_WEBHOOK_URL }}

Note we are using the ternary expression in GitHub Actions for the value of job-status above.

slack-send v.s. Github Slack Integration

Github Slack Integration offers "on-click" experience with almost no configurations like the one above. In addition, it sends notification on GitHub issues open/close, pull requests, GitHub Action workflow status, etc. The easier setup and richer notifications makes Github Slack Integration a better choice for team-collaboration managing multiple repositories with a common communication standards

slack-send, on the other hands, supports sending any information about GitHub Action workflow, not just status. It also supports custom messages; we can inject emoji or custom pictures in the notification messges, which is a big plus for those who love personal customizations and focuses on only success-or-fail of each GitHub action run.

info

With slack-send we also do not need to run /invite @GitHub so our channel is completely private.