Integrate Slack with Github

This article explains how to create a Slack Bot and configure a simple Github Action workflow using slackapi/slack-github-action, which is one of the many ways to implement this integration.

Create a Slack Bot

Step 1: Go to Slack API Apps

URL: https://api.slack.com/apps

Click “Create New App” and then “From Scratch” Give it a name (e.g. GitHub PR Bot) and choose your workspace below.

Step 2: Add Permissions

• In the left sidebar, go to OAuth & Permissions.
• Under Scopes / Bot Token Scopes, click Add an OAuth Scope.
• Add this permission: chat:write (you can add others as well)

Step 3: Install the app to your workspace

• Scroll up and click the “Install to Workspace” button.
• Slack will ask you to authorize the app and approve it.

Step 4: Copy the bot token

• After installation, you’ll see a new section: OAuth Tokens for Your Workspace. There will be a token labeled: Bot User OAuth Token. Copy it, it will start with xoxb-.

Step 5: Add it to GitHub Secrets

In your GitHub repository:

• Go to Settings / Secrets and variables / Actions
• Click New repository secret
• Name it: SLACK_BOT_TOKEN for example
• Paste the token you copied from Slack

Github workflow

• Create a folder .github/workflows in your repo.
• Add a yml file with the workflow, e.g. pr-alert.yml. Note that this uses @v2 of the action, which uses different payload format from @v1.

name: slack-notification

on:
  pull_request:
    types: [opened, ready_for_review]
    paths:
      [
        "src/**",
        ".github/workflows/pr-alert.yml",
      ]

jobs:
  slack-notifications:
    name: Sends a message to Slack when a pull request is opened
    runs-on: ubuntu-latest
    if: ${{ !github.event.pull_request.draft }}
    steps:
      - name: Post to Slack (v2)
        uses: slackapi/slack-github-action@v2
        with:
          method: chat.postMessage
          token: ${{ secrets.SLACK_BOT_TOKEN }}
          payload: |
            channel: "<channel_id>"
            text: "*New PR waiting for review:* <${{ github.event.pull_request.html_url }}|${{ github.event.pull_request.title }}>"
            blocks:
              - type: section
                text:
                  type: mrkdwn
                  text: "*New PR waiting for review:*\n<${{ github.event.pull_request.html_url }}|${{ github.event.pull_request.title }}>"
              - type: section
                fields:
                  - type: mrkdwn
                    text: "*Opened by:*\n${{ github.event.pull_request.user.login }}"

• Replace <channel_id> with the id of the Slack channel where you would like to post your messages. By the time of writing, you can find this id by clicking on the # channel-name in the header, a popup will open, and at the bottom there is Channel ID: C19FYW2BHDF for example.

IMPORTANT: Don’t forget to invite the bot in the channel, otherwise you’ll get an error.

IMPORTANT: It goes without saying, but don’t paste you API key inside the yml file, use the ${{ secrets.SLACK_BOT_TOKEN }} variable, as described above!

• Use whatever template you like, this is just an example that worked well for us.