How does one set up a code review using Gitlab? I see it listed as a feature on the Gitlab website, but I can\'t seem to find instructions on how to set one up (For that matter
You can see submitted code in Merge Request for other repository or in current repository.
example http://demo.gitlab.com/diaspora/diaspora/commits/master
Then you can add comments to committed file changes (button Reply) or to the whole commit
example http://demo.gitlab.com/diaspora/diaspora/commit/42f47626890218a180870bc3f44ec57625b0779c
The resulting communication is code review. However, I personally recommend to do code review on one PC with face-to-face communication whenever possible, and use tools for recording results or when more formality is needed.
For a file revue that has a lot of commits, e.g. http://demo.gitlab.com/diaspora/diaspora/blame/master/README.md look at it using blame to understand who did what. However in this view there is no option to communicate and add comments. I would recommend just add changes as comments in this case.