🔔 Notify Slack on CI Failures

[jasonBirchall]

User Need

As a developer on an app team
I want CI failures to trigger notifications to a specified Slack channel
so that my team is promptly informed and can address issues quickly.

Value

• Reduces time to detect and address CI pipeline failures.
• Increases visibility of CI pipeline status across teams.
• Minimises the risk of ignoring CI failures, improving overall software quality and reliability.

Functional Requirements (What):

• Create a custom GitHub Action that triggers on CI pipeline failure.
• Add functionality to specify a Slack channel for notifications.
• Please make sure the message includes relevant details about the failure, such as the repository name, branch, and error logs.

Non-Functional Requirements (How):

• Notifications should be sent within 30 seconds of a CI failure.
• Use secure methods for storing and handling Slack Webhook URLs.
• Ensure the custom GitHub Action is reusable and documented for other projects.
• Notifications should follow a consistent and readable format.

Acceptance Criteria:

• When a CI failure occurs, a message is sent to the specified Slack channel.
• The message contains the repository name, branch, and failure summary.
• The solution is tested and works for multiple Slack channels in different configurations.
• Documentation is provided for setting up the custom GitHub Action in other repositories.

Assumptions (Optional):

• The team has access to the necessary permissions to set up and use Slack Webhook URLs.
• The CI pipelines are managed using GitHub Actions.
• Users have existing Slack channels dedicated to CI/CD alerts or can create new ones.

Notes:

• Currently, only deployment alerts are routed to #govuk-deploy-alerts, which covers the CD portion. This feature will extend similar visibility to the CI portion of pipelines to specific user channels.
• Here is the conversation that started this request.