Test GitLab merge requests before they merge

Teams using GitLab.com or GitLab Self-Managed can now build merge requests and test proposed merges against their target branches with merged-results builds. Merge request builds test the source branch, while merged-results builds test the proposed merge, helping catch integration failures before merging.

Set up merge request builds

In your pipeline's GitLab settings:

1. Enable Build merge requests to build a merge request when it opens or receives new commits. If Build branches is also enabled, Buildkite avoids creating a duplicate branch build for an active merge request.
2. Optionally, enable Build merged results commit to test the proposed merge with its target branch instead of testing the source branch alone.
3. If your target branch changes frequently, enable Rebuild when target branch changes to keep merged-results builds up to date.

To control build volume when a target branch changes, Buildkite rebuilds up to the 20 most recently created affected merge requests.

These settings are also available through the REST API. See the GitLab documentation to learn more.