This is a very short (tl;dr) how-to guide to using Git and Gerrit for MediaWiki development. For a tutorial which includes explanations, see Gerrit/Tutorial .

First steps:

1. Install and configure Git.
2. Create an SSH key (steps 1-3 are enough for Gerrit). Create a Wikimedia developer account.
3. Log in and add your public key to gerrit.
4. Also add your public key to LDAP using the toolsadmin interface or Special:NovaKey on wikitech.
5. Install git-review and set it up .

Warning:

To interact with Toolsadmin/Wikitech and/or Gerrit, developers must use different SSH keys than the ones they use to connect to production servers. Production access is extremely sensitive and "Prod Keys" should never be used in things other than production instances.

Get the code:

For MediaWiki core:
git clone ssh://<username>@gerrit.wikimedia.org:29418/mediawiki/core.git mediawiki

Or, for an extension:
git clone ssh://<username>@gerrit.wikimedia.org:29418/mediawiki/extensions/<extension>.git

Or, for a skin:
git clone ssh://<username>@gerrit.wikimedia.org:29418/mediawiki/skins/<skin-name>.git

Write and send your new code:

git checkout master

git pull

git checkout -b <meaningful-branch-name>

# Now write some code. See the Git commands "add", "rm" and "mv" to add, remove or rename files. When the code is ready:

git commit --all # In the Gerrit world, you should do this only once per branch! Remember to follow the commit message guidelines.

git show # Make sure that you are sending what you want to send. Press "q" to quit.

git review -R # This sends your code to Gerrit.

If you receive errors with the "-R" switch you may be using out of date "gerrit-tools" instead of "git-review"

Add potential change reviewers:

On Gerrit, click your change. Under "Reviewers", click the "Add Reviewer" button. Write a reviewer name in the input box. If you don't know who to invite for reviewing, try the maintainer for the component you've edited, or ask on IRC (#wikimedia-dev ^connect).

If the reviewer asks you to make a change, make it and amend your commit:

git review -d <change ID or URL of patch> # e.g. 1234 in gerrit.wikimedia.org/r/1234 or https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1234

# Make the needed changes to the source files.

git commit --all --amend # You can do this more than once. You can change the commit message, but make sure to leave the "Change-Id" line intact.

git review -R # This creates a new patch set in the same Gerrit change, and sends an invitation to review the code again.

To review other people's code, just follow the same steps to amend a change described above, using the corresponding <change ID>.