gitlab-org--gitlab-foss/doc/development/automatic_ce_ee_merge.md

Automatic CE->EE merge

GitLab Community Edition is merged automatically every 3 hours into the Enterprise Edition (look for the CE Upstream merge requests).

This merge is done automatically in a scheduled pipeline. If a merge is already in progress, the job doesn't create a new one.

If you are pinged in a CE Upstream merge request to resolve a conflict, please resolve the conflict as soon as possible or ask someone else to do it!

Note: It's ok to resolve more conflicts than the one that you are asked to resolve. In that case, it's a good habit to ask for a double-check on your resolution by someone who is familiar with the code you touched.

Always merge EE merge requests before their CE counterparts

In order to avoid conflicts in the CE->EE merge, you should always merge the EE version of your CE merge request first, if present.

The rationale for this is that as CE->EE merges are done automatically every few hours, it can happen that:

1. A CE merge request that needs EE-specific changes is merged
2. The automatic CE->EE merge happens
3. Conflicts due to the CE merge request occur since its EE merge request isn't merged yet
4. The automatic merge bot will ping someone to resolve the conflict that are already resolved in the EE merge request that isn't merged yet

That's a waste of time, and that's why you should merge EE merge request before their CE counterpart.

Avoiding CE->EE merge conflicts beforehand

To avoid the conflicts beforehand, check out the Guidelines for implementing Enterprise Edition features.

In any case, the CI ee_compat_check job will tell you if you need to open an EE version of your CE merge request.

Conflicts detection in CE merge requests

For each commit (except on master), the ee_compat_check CI job tries to detect if the current branch's changes will conflict during the CE->EE merge.

The job reports what files are conflicting and how to setup a merge request against EE.

How the job works

1. Generates the diff between your branch and current CE master
2. Tries to apply it to current EE master
3. If it applies cleanly, the job succeeds, otherwise...
4. Detects a branch with the ee- prefix or -ee suffix in EE
5. If it exists, generate the diff between this branch and current EE master
6. Tries to apply it to current EE master
7. If it applies cleanly, the job succeeds

In the case where the job fails, it means you should create a ee-<ce_branch> or <ce_branch>-ee branch, push it to EE and open a merge request against EE master. At this point if you retry the failing job in your CE merge request, it should now pass.

Notes:

• This task is not a silver-bullet, its current goal is to bring awareness to developers that their work needs to be ported to EE.
• Community contributors shouldn't be required to submit merge requests against EE, but reviewers should take actions by either creating such EE merge request or asking a GitLab developer to do it before the merge request is merged.
• If you branch is too far behind master, the job will fail. In that case you should rebase your branch upon latest master.
• Code reviews for merge requests often consist of multiple iterations of feedback and fixes. There is no need to update your EE MR after each iteration. Instead, create an EE MR as soon as you see the ee_compat_check job failing. After you receive the final approval from a Maintainer (but before the CE MR is merged) update the EE MR. This helps to identify significant conflicts sooner, but also reduces the number of times you have to resolve conflicts.
• Please remember to always have your EE merge request merged before the CE version.
• You can use git rerere to avoid resolving the same conflicts multiple times.

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