Gerrit is a tool for web-based code review -- similar to ReviewBoard, but with some neat features. For instance, it has built-in CI bot (Code Integration) support and general workflow is integrated with Git. It's used for patch submission to Trojitá.
The first step is logging in. Use your KDE Identity account (or get one here) to log in to Gerrit. Go into Settings -> SSH Keys and upload your public SSH key in there. If you don't have these so far, you need to create one. For starters, there is a Git QuickStart Guide that will help you to create SSH keys and clone KDE repository you are interested in. Also be sure to configure your name and e-mail in git before you proceed.
Patches can be uploaded for review by any KDE user with legit Identity account, so you are not obligated to have a KDE Developer account at all. Here is a little hint to get started. We will assume that your repository is already cloned from KDE servers. Take a note that you obviously need to do this once per repo.
# At first, let's add a new git remote git remote add gerrit ssh://YourKdeIdentityUsername@gerrit.vesnicky.cesnet.cz:29418/RepositoryName # Gerrit needs a client-side hook for putting the Change-Id tags into commit messages scp -p -P 29418 YourKdeIdentityUsername@gerrit.vesnicky.cesnet.cz:hooks/commit-msg .git/hooks/
So you've got some code changes now and you want to submit these into a Change. Good practice is to use "topic branch here" and do everything in it, so you don't affect any remote branches. Simply make commits (one per change) and when you're done, push them to a "magic ref". Instead of doing stuff like git push gerrit master, you do:
git push gerrit HEAD:refs/for/master
The above will open a review request(s) on top of master, one for each commit that you made.
The key point is the refs/for/ prefix. This is a magic ref, or a magic branch. It does not really exist on-disk, but whenever you push there, Gerrit notices that you want to update or create a new patch/change/request/... and do the right thing.
Gerrit will tell you what has happened -- either everything went well and then you got a link to a change request on the web, or something broke and then you should get an error message about what was it. There are also advanced possibilities, see further down in this page for them.
Any registered user can give you +1 .. -1 points for Code Review. KDE developers can give you +2 .. -2 points for any review request. Your change becomes submittable when it has at least single +2 grade and there are no -2 "veto" reviews.
Just amend/rebase/modify-in-any-other-way your commit and push to refs/for/targetBranchName. Here is a way to do this with amend:
# Make some changes over existing commit git add -u git commit --amend git push gerrit HEAD:/refs/for/targetBranchName
As long as the Change-Id line in the commit is preserved, Gerrit will do the right thing and notice that it's an updated version of an existing change.
Go to settings, add a project, and then make sure all checkboxes are ticked. The default operation adds a project to your watchlist, but no events would be delivered to you.
Please note that this is a pretty recent version of Gerrit which differs in a few ways from the version used by e.g. the Qt project. Most of the changes are in the UI, e.g. to apply stuff locally, use the Download menu at the top-right corner of the change view.
Gerrit works well out-of-the-box with regular git functionality, but for some advanced usage, you might want to use script by Qt's developers -- gpush. It provides smart interface to some Gerrit features. You can get it along with qtrepotools from official Qt repository. Just make sure that its bin directory is in $PATH. Here are some examples of its usage:
# Pushes HEAD:refs/for/branch to 'gerrit' without any reviewers git gpush # Pushes HEAD:refs/for/$TRB to 'gerrit', adding mariuso as a reviewer # and sends thiago a CC mail git gpush +mariuso =thiago # Pushes HEAD:refs/for/buildsystem to 'gerrit', no reviewers git gpush :refs/for/buildsystem
Once a change is approved and submitted to git, Gerrit automatically inserts a proper note about that into git. Here's how to enable showing of them. At first, configure git so that it gets fetched automatically (assuming origin is your KDE remote, and that at least one change has been already merged:
git config --add remote.origin.fetch refs/notes/review:refs/notes/review git fetch origin
To show this information, add a fancy argument to e.g. git log:
$ git log --notes=review commit 39f98861cec1cba192171b6ad998328b16106c46 Author: Jan Kundrát <firstname.lastname@example.org> Date: Sat Sep 6 17:30:57 2014 +0200 tests: Improve debugging for extra unexpected child tasks I can as well just leave this in instead of removing it every time I hit a failure in the subsequent QVERIFY. Change-Id: Ia4a7c72d0193827e013bfe3d47a0bd7a99567058 Notes (review): Code-Review+2: Jan Kundrát <email@example.com> Submitted-by: Jan Kundrát <firstname.lastname@example.org> Submitted-at: Mon, 08 Sep 2014 09:19:44 +0200 Reviewed-on: https://gerrit.vesnicky.cesnet.cz/r/11 Project: trojita Branch: refs/heads/master
If you dislike the refs/for/ prefix, you can set up gerrit so that you can push "directly to branch", yet git will do the right thing for you:
git config remote.gerrit.push refs/heads/*:refs/for/* git push gerrit
You can also add reviewers while you submit stuff for review. To add three people, email@example.com, firstname.lastname@example.org and email@example.com, do it like this:
git push gerrit HEAD:firstname.lastname@example.org,email@example.com,firstname.lastname@example.org
At these points you can clearly see advantages of git gpush script, because it's more user friendly and supports nicknames along with emails as well.
As Gerrit is based on git, there is a ton of possible workflows. Maybe we should settle on one and thoroughly document it?
What tricks do you find neat?
The name of the project repository at KDE's git and in gerrit have to match. One can only add regular project repositories, not personal clones or scratch repos.
At first, set up KDE's infrastructure so that any pushes propagate to Gerrit:
cd kde/repo-management # do an equivalent of commit 6bd604f73902d9a14c05a2abb88da5e1838ce2ea echo ssh://email@example.com:29418/YourRepoName \ > repo-configs/remote-update/YourRepoName.git git commit -a git push
Now setup the project in Gerrit:
ssh -p 29418 gerrit.vesnicky.cesnet.cz gerrit create-project \ --parent sysadmin/gerrit-kde-traditional-projects NameOfGitRepo
This creates a refs/meta/config branch within Gerrit's git copy, which gets pushed to git.kde.org, which in turn notices that it should push missing branches to Gerrit, and stuff just works from that time on.
Everything was deployed to CESNET's cluster within the XIFI project. The VM runs within OpenStack, and everything is deployed by Puppet. Ask jkt for details, full release is pending.