Core Reviewer’s Guide

Maintaining the Core Group

+/-2 votes

Only core reviewers can give +2 and -2 votes. A vote of +2 indicates that the core reviewer agrees that the patch can merge as is.

A vote of -2 blocks a patch completely, it should only be given in exceptional cases. For example, if a patch is approved and currently in the gate pipeline, a -2 will block it from merging.

Note that -2 votes are the only votes that are not reset when a new patch gets uploaded. The core reviewer that gave a -2 is the only person that can remove it again.


Once a patch has at least one +2 vote and neither any -2 votes or a Work in Progress tag set, it is ready to be merged. Any core reviewer can approve such a patch. A core reviewer can give a +2 and approval in the same review.

Note that some projects hosted in OpenDev have a policy of requiring two +2 votes instead of one. The OpenDev infrastructure enforces only a single +2 vote, the rest is policy.

Work In Progress

The “Work in progress” (WIP) label tells anyone looking at a change that more updates are still needed. Both the change’s owner and any core reviewer can set the WIP statusː

  • A change owner can set this label on their own review to mark that additional changes are still being made, and to avoid unnecessary reviews while that happens.

  • A core reviewer can set the WIP label to acknowledge that a contributor will definitely need to do more work on a change rather than merely expressing an opinion on its readiness. This can be a great convenience to fellow reviewers. It allows the core reviewer to politely send the message that the change needs additional work while simultaneously removing it from the list of ready changes until that happens.

A WIP label gets reset when a new patch is uploaded. The reviewer that sets a WIP label, can also reset it.


As covered in Automated Testing, developers can take steps when Zuul tests fail. Core reviewers, like other developers, can use these same steps when rerunning tests. Core reviewers have an additional tool for cases where gate testing fails due to reasons unrelated to the current change, re-approval.

Core reviewers can approve changes again to trigger gate testing for that particular change. Core reviewers should still heed the advice in Automated Testing to ensure that unrelated failures are properly tracked. Note that the change will directly enter the gate pipeline if and only if it has already a +1 vote from Zuul, otherwise it will first enter the check pipeline like a “recheck” would.