How to trigger pipeline runs only after PR merge (not on PR open/update)

If you want your Spacelift pipeline to run only when a pull request is merged to your main branch, and not when PRs are opened or updated, you can achieve this using a Push policy.

Solution

Follow these steps to configure your stack to only trigger runs on PR merge:

1. Keep your stack's tracked branch set to main

2. In your Git provider (e.g., Bitbucket), keep Push events enabled in the webhook configuration

3. Create a Push policy with the following code:

package spacelift

# Track ONLY pushes to the stack's tracked branch (e.g., main)

track {
  input.push.branch == input.stack.branch
}

propose { false }

ignore { not track }

How it works

This Push policy works by:

• Tracking only the main branch: The track rule ensures that only pushes to your stack's tracked branch (typically main) are processed

• Disabling proposed runs: The propose { false } rule prevents any proposed runs from being created

• Ignoring other branches: The ignore { not track } rule ignores all pushes that don't match the tracking criteria

When a PR is merged, it creates a push to the main branch, which will trigger the pipeline run. However, when PRs are opened or updated on feature branches, they will be ignored by this policy.