Gerrit/Advanced usage

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Visual representation of what MediaWiki's development workflow looks like

The basic instructions to set up and operate with Git and Gerrit are described at the Tutorial (see also its shortest version).


This page mostly documents how to do things "the hard way" in gerrit. The git review tool continues to improve, and now contains built-in mechanisms to push to a branch, upload a set of dependent patches, etc. You should probably review man git review before deciding that you need to proceed further here.


Setup SSH shortcut (optional)[edit]

It's easier to access the repository if you don't have to specify the full every time. You can edit your ~/.ssh/config file and add

Host gerrit
Port 29418
User yourusername

Then you can use "gerrit" instead.

git review -s adds a gerrit remote to git which should make this step unnecessary. Cscott (talk)

Submitting patches[edit]

Setting up a repository for git-remote[edit]

Most repositories should already have information for git-remote where your repository is and what the name of the master branch is. The information is stored in a .gitreview file in the root of the repository. If this file does not exist yet, you need to create and commit it. The format is the following:


The host and project fields are mandatory. The other fields are optional: port defaults to 29418 and defaultbranch defaults to master .

Howto - Merging your amend back into your branch[edit]

This section is optional. It's offered as a convenience way to offer your a solution to a common problem. At this stage, your new changeset is already in Gerrit.

After you have amended your change, you may want to merge it back into your local branch.

You can do this by going to the Gerrit change in question.

Here is an example:

Go to the Download section and copy cherry pick.

We will select patch set 4.

Switch back to your branch. You will be in your review branch where you just made your change.

Note: use the branch relevant to your change number.

git checkout mingle-fr-2012-59

Paste in the cherry pick and merge any conflicts.

git fetch ssh://<USERNAME> refs/changes/69/7669/4 && git cherry-pick FETCH_HEAD

Perform a git add on the modified files.

git add payflowpro_gateway/payflowpro.adapter.php

Do not forget to check your status and run a diff.

git diff

You should see there are no differences:

diff --cc payflowpro_gateway/payflowpro.adapter.php
index d7e510a,738c9df..0000000
--- a/payflowpro_gateway/payflowpro.adapter.php
+++ b/payflowpro_gateway/payflowpro.adapter.php

Then commit the changes:

git commit -m 'Merging patch set 4.'
[mingle-fr-2012-59 4e82e5a] Merging patch set 4.
 1 files changed, 3 insertions(+), 3 deletions(-)

Submitting a change to a branch for review ("backporting")[edit]

Backporting fixes discusses backporting changes to MediaWiki core (coordinate with the MediaWiki Release Manager, handling in Phabricator, etc.)

In this example, we'll backport Gerrit #Ib27792 from master to REL1_20. The basic idea is to use git cherry-pick to apply the changes from the commit to master to a different branch.

Before you start, look up the git commit hash of the commit that was merged into master. This can be found on the Gerrit change page. Scroll down to the last Patch Set, and the git commit hash is between "Patch Set NN" and "(gitweb)" (not to be confused with the Gerrit Change id which starts with a capital 'I'). Make sure that this commit was indeed merged into the master branch. If it wasn't then wait until it has been reviewed and merged in master — the commit may still be amended and we don't want to merge an old version).

$ git fetch origin

# The git commit hash of the change in master.
$ git show d4f2c0e8f76a7634fce1631669f4ce037965d8b5

$ git checkout origin/REL1_20
$ git reset --hard origin/REL1_20 # Ensure latest version, undo any local dependencies
$ git cherry-pick d4f2c0e8f76a7634fce1631669f4ce037965d8b5

# Do not change the commit message. In particular leave the
# "Change-Id" intact at the bottom of the message, since this is
# what Gerrit uses to relate the master change and the branch merge.
# If the merge causes conflicts, you should fix them manually,
# use git add <files> and run git commit. Move the "Conflicts" section
# of the commit message before "Change-Id", so "Change-Id" remains at
# the bottom of the message, otherwise the push will be rejected.

# Verify history looks as expected
$ git log --graph --decorate --oneline -n5

# View the original change in Gerrit and look up the topic-name,
# then use it below in place of "topic-name", e.g. "refs/for/REL1_20/bug/36151"
# or "refs/for/wmf/1.21wmf1/my-topic-name"
$ git push origin HEAD:refs/for/REL1_20/bug/36151
remote: New Changes:
 * [new branch]      HEAD -> refs/for/REL1_20/bug/36151
Is there any need to use complicated git push instead of git review here? -- S Page (WMF) (talk) 02:28, 17 May 2013 (UTC)
The only reason would be so that you can give it a new topic. So alternatively, after the git log check, look up the topic name first (or think of a new topic) and do git checkout -b random-new-topic-name then followed by regular git review -R (instead of git push); as of git-review version 1.23, it will reuse the original topic.
git review -R remote-branch-name works too if you want to push to a remote branch from a review branch.

As a result:

Acting on remote branches[edit]

By default, your local clone will only have a local master branch set up to track the remote master branch. Tracking means that whenever you fetch objects from the remote repository, git status or git branch will be able to tell you how up-to-date is your local branch, which is very useful. So, whenever you want to regularly act on a remote branch (lets says REMOTE_BRANCH, you want to setup a one locally (REMOTE_BRANCH too to easily remember about it) that track it (with -t).

git branch -vv will give the full details:

$ git clone ...
$ git checkout -b REL1_19 -t gerrit/REL1_19
$ git branch -vv
  REL1_19 3b2bfd3 [gerrit/REL1_19: ahead 1] .gitreview for REL1_19 branch
* master  13169c8 [gerrit/master: behind 1] * (bug 34212) ApiBlock/ApiUnblock a[...]

Pushing having used automatic setup[edit]

git-review accepts, as an optional argument, the branch name to interact with. When that argument is not specified, it falls back to look for the defaultbranch parameter in a .gitreview file at the root of the repository.

Every branch should have a .gitreview having a correct defaultbranch value. For mediawiki/core.git, else people will have to use something like: git-review BRANCH_NAME.

Pushing having used manual (Windows) setup[edit]

To change where you push to for review having performed a manual setup, run git config alias.push-for-review "push gerrit HEAD:refs/for/BRANCH_NAME" to create the local alias, then use git push-for-review as per usual.

Committing to non master[edit]

To make a change to the 1.17 branch, create a branch and tag, and push both:

 git checkout -b REL1_17 origin/REL1_17
<make code changes>
 git add <files-changed>
 git commit
 git push gerrit REL1_17
 git tag 1.17.3
 git push --tags

Partial revert of previous commit[edit]

 git show <commit> -- <path> | git apply -R

<commit> Can be found in gerrit patch view in small letters next to text Patch Set N. Then push for review normally.

Unlink bogus dependencies (rebase changes)[edit]

Example for,5154

git fetch --all # To make sure we have latest changes
git review -d Ie6e3c9be
git rebase -i gerrit/master # Delete the commits you want to get rid of
git commit --amend # Add a note
git review -f # -f deletes the branch after submit

Create a dependency[edit]

If you are about to create a patch that depends on another (unmerged) patch, or if you already submitted a patch but need to fix the dependency (i.e. currently it is based on master and would break if merged without the dependency, or maybe you squashed your change on top of the dependency). Then this is the section you're looking for. If you want to fix the patch to have the right dependency rather than to create a new patch with a dependency, then make sure your working copy is clean (no uncommitted changes).

git fetch --all # Make sure we have latest info from the repository
git review -d 1234 # Gerrit change number of the change you want as dependency ("parent")

Now we need to make sure the patch has the correct git-parent. Depending on whether you are creating a new patch or fixing an existing patch, there is two different ways to do this. If you are starting fresh:

git checkout -b bug/1234 # Creates a new branch, with the current branch (the dependency) as parent
# Edit files: make your changes
git add someFile.php some/other/file.js 
git commit # Commit your patch

git log -n5 --decorate --pretty=oneline # Verify that the last 5 entries of the log now start with:
# * (HEAD, bug/1234) your change
# * (review/john/700) the dependency
# * (gerrit/master)

git push gerrit HEAD:refs/for/master # or git review

If you need to amend your patch to have the correct dependency:

git branch # Take note of the review/* branch that was created for this, it has an "*" in front of it
git checkout bug/1234 # Check out the local topic branch of your change
git rebase review/john/7000 # The branch name of the gerrit change we checked out earlier

# Resolve conflicts if needed,
# - use "git status" to see the files that need resolution
# - after fixing it in your editor, "git add filename" for each of the fixed files 

git rebase --continue

git log -n5 --decorate --pretty=oneline # Verify that the last 5 entries of the log now start with:
# * (HEAD, bug/1234) your change
# * (review/john/700) the dependency
# * (gerrit/master)

git push gerrit HEAD:refs/for/master # or git review
If you wish to set a topic, use:
git push gerrit HEAD:refs/for/master/myawesometopic # Append your topic name


git review -t myawesometopic

Cross-project dependencies[edit]

You can also use cross-project dependencies (e.g. an extension that requires a change in core before it can be merged). You can accomplish this by adding e.g. Depends-On: I75b266da99e7dcb948f10d182e7f00bb3debfac6 in the footer of a commit message. Use the full Change-ID (‘I’ + 40 characters). See for more details.

Splitting a commit into smaller ones[edit]

Explained in detail at Gerrit/split a submitted change.

Removing your local branch after submitting your change into Gerrit[edit]

you@yourmachine:~/puppet (production)$ git checkout -b mycoolfeature
you@yourmachine:~/puppet (mycoolfeature)$ vi foobar
you@yourmachine:~/puppet (mycoolfeature)$ git commit -a -m "Committing my cool feature"
you@yourmachine:~/puppet (mycoolfeature)$ git review -f
you@yourmachine:~/puppet (production)$

If the -f flag is passed to git-review, it will try to submit the change, and if it succeeds it will switch back to the master branch (production in this case) and delete the feature branch.

Merging a submodule into a parent project[edit]

See Gerrit/merge submodule.

Using a personal sandbox for personal branches[edit]

Gerrit allows the creation of "personal sandboxes" where users can stash code that they're working on in a personal branch that doesn't require admin intervention for pushes. See Gerrit/personal sandbox.


For problems and how to solve them, see Gerrit/Troubleshooting.

Working on an existing change set[edit]

Sometimes you want to work on a change set started by some else and then upload your changes as a new patch set.

# Note in the gerrit URL the number reference to the change set, 
# e.g.,, thus 70112

# In your local copy of the master branch, pull down the change set 
# and switch to that branch with the following command.
git review -d 70112

# Make any necessary changes and commit them as an amendment, 
# adding appropriate comments to the commit message.
git commit --all --amend

# Push the patch set up to gerrit as usual.
git review -R

# Other developers can then update their local copy of the change set 
# with the following command.
git review -d 70112

NOTE: DO NOT use the -m flag to specify a commit summary: that will override the previous summary and regenerate the

Change-Id. Instead, use your text editor to change the commit summary if needed, and keep the Change-Id line intact. (See : [1])

Reviewing code[edit]

Viewing and commenting on code[edit]

The basic functionality is explained in the Git and Gerrit tutorial.

Some extra bits:

  • Old Version History dropdown menu. This menu will allow you to change what changes you're reviewing. This is helpful if you reviewed a past changeset, and want to make sure your changes were taken into account. Rather than reading through the entire changeset diff'd against the base commit, you can read only the differences between the current changeset and the changeset you reviewed. There's a bonus, too: You can see your comments on the left hand side of the If there was a rebase commit, there will be garbage in the diffs, but you can read things one changeset at a time and it will still be faster.
  • Diff All Unified button:
  • Opens the diff(s) in a new tab. You can double-click on a line and comment on that line, then save a draft comment! Then, click "Up to change" to go back to the changeset.
  • For commits that contain whitespace changes (i.e. indent a block that was changed), it is best to set the diff-preferences appropriately to make it easier to review. When viewing a diff, on top there is a link "Preferences". Then there is two important settings to focus on. "Ignore Whitespace" and "Intraline Difference". The last one (Intraline Difference) is especially useful if a block of code was indented, as this setting will show the added tabs themselves allowing other changes to be recognizable without having to compare every word in your mind (see screenshot).

How to comment on, review, and merge code in Eclipse[edit]

Code review in Eclipse

As an alternative to Gerrit's web interface, you can also review code from Eclipse using the Mylyn task-management framework. To get started, download and install Eclipse, and then install Mylyn from the Install New Software menu (as of Oct 5th, 2013 you need the snapshots update site to use the Wikimedia Gerrit installation). When you next launch Eclipse, you'll be prompted to add a task for Mylyn. From there, you'll need to install the connector for Gerrit, specify as the server URL, and add your username and password.

Diff / comment interface in Eclipse

How to review and merge code via command line[edit]

Using dippy-bird you can easily do command line review and merging. The query parameter is the change you want to deal with.

php dippy-bird.php --username=USERNAME --port=29418 --action=submit --query=12345

You can therefore use that to approve a range of commits:

for i in {51541..51545}
   php dippy-bird.php --username=USERNAME --port=29418 --action=submit --query=$i

Mass-approving changes across repositories[edit]

We might sometimes have to generates a ton of changes, for example when doing a similar change on all our repositories. In the past, this happened after the MediaWiki extensions got migrated to Git since we had to add a .gitreview file to each repository.

First, you can query gerrit for a list of change using the CLI! A useful alias:

alias gerrit='ssh -p 29418 gerrit'

Then use that to execute a query such as all open changes on topic dotgitreview:

gerrit query 'status:open topic:dotgitreview'

With some shell magic, you can get a list of change number:

gerrit query 'status:open topic:dotgitreview' \
| egrep '^  number' | cut -d\  -f4- > CHANGES_NUMBERS

Then loop on them and remotely approve the changes:

for i in `cat CHANGES_NUMBERS`; do gerrit review --verified=+1 --code-review=+2 --submit "$i,1"; done


For problems and how to solve them, see Gerrit/Troubleshooting.

How to create a repository ("Gerrit project")[edit]

See "Request a new Git repository". There's a form to fill out. It should get processed very quickly (within a couple of days).

Other tips[edit]

Gerrit project dashboard[edit]

Each Gerrit repository has one or more dashboards that can be customised. The default dashboard is shown when you click on a project link anywhere in Gerrit. For example, clicking "mediawiki/core" on a commit page related to MediaWiki core will take you to,dashboards/default.

In Gerrit, dashboards are created in groups. Every repository inherits the "default" dashboard group from the "All-Projects" meta project. By default a project's default dashboard defaults to "default:recent". You can change what dashboard is used by default in the project.config file in the refs/meta/config branch of a repository. Detailed instructions are below.

Change an existing dashboard[edit]


  1. Clone the repository if you haven't already.
  2. Check out the dashboard group's configuration branch. Here is an example of checking out a dashboard group called "custom": git fetch origin refs/meta/dashboards/custom:refs/remotes/origin/meta/dashboards/custom && git checkout meta/dashboards/custom
  3. Change the dashboard's configuration file to your liking. See Project Dashboards in Gerrit Documentation for the syntax.
  4. Be sure to test any changed queries by entering them in the regular search box in Gerrit in your browser.
  5. Stage your changes and make a commit (git add -p && git commit)
  6. Push the commit for review: git push origin HEAD:refs/for/refs/meta/dashboards/custom
  7. The change is now up for review to be merged.

Create a new dashboard group[edit]

  1. Make sure you have push access to refs/meta/* on the repository in question.
  2. Clone the repository if you haven't already.
  3. Create a new orphan branch locally.
  4. Create the the dashboard's configuration file.
  5. Stage your changes and make a commit.
  6. Push the commit: git push origin HEAD:refs/meta/dashboards/custom

Set the default dashboard[edit]

  1. Clone the repository if you haven't already.
  2. Check out the repo configuration branch: (See Git/aliases) git fetch origin refs/meta/config:refs/remotes/origin/meta/config && git checkout meta/config
  3. Set the default field in a dashboard section, like so:
      default = refs/meta/dashboards/custom:custom
  4. Stage your changes and make a commit.
  5. Push the commit for review: push origin meta/config:refs/for/refs/meta/config
  6. The change is now up for review to be merged.

Add navigation links[edit]

Since Gerrit 2.12 it is possible to customise the navigation links in the "My" menu along top of the web interface. By default these contain "Changes", "Draft Comments", "Starred Changes" and more. They can be changed from the preference settings at

For example, to add a link to the Performance Team's dashboard:

  1. Open
  2. Add an entry with URL #/projects/performance,dashboards/custom:custom and name "Perf Team" or some such.
  3. Save changes!

Code Review links[edit]

Links to old SVN Code Review revisions are stored in commit notes. They may be fetched for display in the git log using the following command:

git fetch gerrit refs/notes/commits:refs/notes/commits

Note this must be done separately for each git repository.

Gerrit review scores[edit]

As above, code review metadata is stored in commit notes and may be fetched using:

git fetch gerrit refs/notes/review:refs/notes/review

To retrieve them regularly, add to your git config.

To display them in git log (similar syntaxes work for related tools):

git log --notes=review

ssh proxy to gerrit[edit]

If gerrit is being slow, when it comes to uploading patches, it might be a network issue. (especially if you are in Europe, at certain times of the day) If you have a server / vm in the US or other proxy that you can use, then you can access gerrit via that.

In your ~/.ssh/config add something like:

  User aude                                                                                            
  Port 29418                                                                                           
  ProxyCommand nc -x %h %p

Then connect to the proxy (e.g. via ssh, with the "-D 8081" option). Then it should work to access gerrit to upload / download patches and may be faster.

See also[edit]