Using Slack with Mergify

While there isn’t a direct integration between Mergify and Slack, you can still achieve notifications in Slack based on Mergify actions by leveraging the GitHub to Slack integration. Here’s a step-by-step guide on how you can set it up:

1. Go to Slack’s GitHub Integration page.

2. Click on the ‘Add to Slack’ button.

3. Invite the GitHub app to the channel you want. Refer to the documentation for more details.

4. Make sure you subscribe to the repositories to receive the mentions as private message for the GitHub Slack app.

Now that the Slack-GitHub integration is complete, let’s see how you can use Mergify to mention a user, which will then notify them on Slack.

The primary idea is to use Mergify’s comment action to mention the PR author, leveraging GitHub’s mention feature. This mention will be forwarded to Slack, notifying the mentioned user.

Here’s an example of a Mergify configuration that comments on a PR if a CI fails and the label is “hotfix”:

pull_request_rules:
  - name: Notify author on CI failure for hotfixes
    conditions:
      - "#check-failure>0"
      - "label=hotfix"
    actions:
      comment:
        message: "@{{author}} :warning: The CI failed on this hotfix PR. Please review the issues and address them."

In the above rule:

• We’re checking if there are any CI failures with #check-failure>0.

• We’re also ensuring that the PR has a label ‘hotfix’.

• If both conditions are met, Mergify will leave a comment mentioning the PR author using @{{author}}. This mention will trigger a notification in Slack if the author has their GitHub integrated with Slack.

By setting up this flow, you can ensure that critical PRs, like those labeled “hotfix”, receive immediate attention from their authors, even if they’re primarily monitoring Slack.