Building Merge Requests - Fork Access

[DavidAntliff]

This is a question rather than a bug report.

I'm using GitLab CE 8.10.4 and Jenkins CI server with this plugin. I've followed the published instructions and my builds are being triggered correctly on merge requests.

However I'm running into a problem with deploy keys. I have a deploy key for the Jenkins user that is used to fetch the upstream target branch. Jenkins and the plugin are configured to perform the merge on Jenkins (not on GitLab). To do this, Jenkins needs to fetch the source branch from the fork, but the upstream deploy key is not valid for this repository, and the build fails.

I need to resolve this fork access problem. Are these viable:

1. Configure GitLab to automatically share a repository's deploy keys with all forks?
2. Or configure GitLab to make a global deploy key available to all users so they can enable it on their own forks?
3. Or configure a global deploy key that provides global access for Jenkins to everything?
4. Or configure GitLab to perform the merge itself, on a branch in upstream, so that Jenkins does not need to fetch the fork?

I set up a similar system with GitHub and the GitHub Pull Request Builder plugin. There was no need for deploy keys per fork because the merge result was made by GitHub in the upstream repository, which is all Jenkins needed to fetch. GitLab seems a bit different in this respect, as merges of the fork with upstream are performed by Jenkins.