Development:Git for developers

This document is for helping you get started on Moodle development with Git. For further details of Git, see Category:Git.

General workflow

Moodle development workflow with Git

In short, the Moodle development with Git looks like this:

You as the contributor commit changes into your personal repository at your computer
You push the changes into your public repository and ask for their inclusion via so called PULL request
Moodle integrators pull the changes from your public repository and if they like them, they put them into Moodle integration repository
The integrated change is tested and finally pushed into Moodle production repository
You update your local repository with all changes from the production repository and the next cycle may start again

This workflow runs in roughly weekly cycles. The integration happens on Monday and the testing on Tuesday. On Wednesday, the production repository moodle.git is usually updated with changes from the last development week.

Most Moodle developers have their public repositories hosted at Github. Alternatively you may want to try Gitorious or the legendary repo.or.cz. In the examples in this guide we assume you'll set up your public repository at Github.

Installing Git on your computer

Install Git on your computer. Most Linux distributions have Git available as a package to install. If you are on Mac, git-osx-installer installs it in few click. If you are Windows user, you should switch to Linux or Mac anyway :-p

Immediately after the installation, set your name and contact e-mail. The name and e-mail will become part of your commits and they can't be changed later once your commits are accepted into the Moodle code. Therefore we ask contributors to use their real names written in capital letters, eg "John Smith" and not "john smith" or even "john5677".

   git config --global user.name "Your Name"
   git config --global user.email yourmail@domain.tld

Setting-up the public repository

1. Go to Github and create an account.

2. Go to the official Moodle Github repository and click on the Fork button. You now have your own Github Moodle repository.

3. Now you need to set up your SSH public key, so you can push to your Github Moodle repository from your local Moodle repository. On Mac you can go on this Github help page. If you are on another system, go to your Github administration page, to the section SSH Public Keys, and you should see a link to a help page. Done? Good! That was the most difficult part!

Setting-up the local repository at your computer

Create a local clone repository of your Github repository. In a terminal:

   git clone git@github.com:YOUR_GITHUB_USERNAME/moodle.git YOUR_LOCAL_MOODLE_FOLDER

This command does several jobs for you. It creates a new folder, initializes an empty Git repository in it, sets your Github repository as the remote repository called 'origin' and makes a local checkout of the branch 'master' from it. The important point to remember now is that your Github repository is aliased as 'origin' for your local clone.

Keeping your public repository up-to-date

Fetching changes from upstream and pushing them to github

Your fork at Github is not updated automatically. To keep it synced with the upstream Moodle repository, you have to fetch the recent changes from the official moodle.git and push them to your public repository. To avoid problems with this it is strongly recommended that you never modify the standard Moodle branches. Remember: never commit directly into master and MOODLE_xx_STABLE branches. In other words, always create topic branches to work on. In Gitspeak, the master branch and MOODLE_xx_STABLE branches should be always fast-forwardable.

To keep your public repository up-to-date, we will register remote repository git://git.moodle.org/moodle.git under 'upstream' alias. Then we create a script to be run regularly that fetches changes from the upstream repository and pushes them to your public repository. Note that this procedure will not affect your local working directory.

To register the upstream remote:

   git remote add upstream git://git.moodle.org/moodle.git

The following commands can be used to keep the standard Moodle branches at your Github repository synced with the upstream repository. You may wish to store them in a script so that you can run it every week after the upstream repository is updated.

   git fetch upstream
   for BRANCH in MOODLE_19_STABLE MOODLE_20_STABLE master; do
       git push github refs/remotes/upstream/$BRANCH:$BRANCH
   done

How it works

The git-fetch command does not modify your current working dir (your checkout). It just downloads all recent changes from a remote repository and stores them into so called remote-tracking branches. The git-push command takes these remote-tracking branches from upstream and pushes them to Github under the same name. Understanding this fully requires a bit knowledge of Git internals - see gitrevisions(7) man page.

Note there is no need to switch the local branch during this. You can even execute this via cron at your machine. Just note that the upstream repository updates typically just once a week.

Preparing a patch

As said earlier at this page, you never work on standard Moodle branches directly. Every time you are going to edit something, switch to a local branch. Fork the local branch off the standard branch you it should be merged to. So if you are working on a patch for 1.9 or 2.0, fork the branch off MOODLE_19_STABLE or MOODLE_20_STABLE, respectively. Patches for the next major version should be based on the master branch.

   git checkout -b MDL-12345-nasty-bug origin/master

Note that if you forget to specify the starting point, the branch is based on the currently checked-out branch. It may not be what you want. It is recommended to always specify the starting point.

To check the current branch, run

   git branch

The current branch is highlighted.

Now go and fix the issue with your favorite IDE. Check the status of the files, view the change to be committed and finally commit the change:

   vim filename.php
   git status
   git diff
   git commit -a

Note that this is safe as the commit is recorded just locally, nothing is sent to any server yet (as it would in CVS). To see history of the commits, use

   git log

Once your local branch contains the change (note that it may consists of several patches) and you are happy with it, publish the branch at your public repository:

   git push

Because we did not specify explicit remote repository, the 'origin' is used. Because we did not specify the branch to push, the Git will use the current branch and push it to the remote repository under the same name (by default, this is a subject of your configuration. See push.default config variable).

Now as your branch is published, you can ask Moodle core developers to review it and eventually integrate it into the standard Moodle repository.

Peer review some code

You need to review someone else work, They must have pushed their work into Github:

Github repository url: git://github.com/PEER_USERNAME/moodle.git
branch name: MDL-XXXXX

1. Run the update script (it will switch to your local master branch and update the code)

2. Add the remote repository (only first time ever, then skip this step) git remote add PEER_USERNAME git://github.com/PEER_USERNAME/moodle.git

3. Fetch the repository, so Git knows about the last changes in it git fetch PEER_USERNAME

4. Switch to a new local 'testing' branch git checkout -b PEER_USERNAME-MDL-XXXXX

5. Import the remote change into this local branch (but not marked as 'committed' so you can see the changes into your IDE)

git merge --squash PEER_USERNAME/MDL-XXXXX

6. You can now test in your favorite IDE. If it supports Git you should see the difference with your local master.

7. Finally you are going to delete this testing branch:

Warning: if you didn't switch, you should still be on testing branch.
the first command revert all the changes to the 'master' state.

git reset --hard git checkout master git branch -d PEER_USERNAME-MDL-XXXXX

Update a branch before pushing your changes

To make diff easy on Github for weekly pull request review, you want to update your branch before to push it to Github. First commit your changes, then run the update script. You have been switched on master branch, so first thing is to go back to your working branch git checkout MLD-XXXX git rebase master At this moment either it worked fine and your branch is updated, either you had some conflicts with one of your previous branch commits. Fix all your conflicts in your editor (like you will fo with CVS) and add the files with 'git add' command. git add file1 file2 file3 ... Now continue the rebasing. git rebase --continue Either it worked and your branch is updated, either one of your other commit created again some other conflicts. Restart the Fix, add, continue rebase steps until you have no conflict. Your branch is updated.

Troubleshooting

do not push your file permission to any repository

git config --global core.filemode false

If you want to delete a remote branch on Github:

git push origin :CONFLICTING_REMOTE_BRANCH_NAME

PHPStorm (beta version) named your 'origin' => 'master' when you cloned your Github repository. It is better to rename it as 'origin'.

git remote rename master origin

You've been working with Git in the early stages when Moodle HQ were experimenting with it. They now changed 'cvshead' to 'master' into upstream (moodle.org Git). You need to rename all your 'cvshead' Github and local branches as 'master'. There what you should do (this is not a script to run, execute the command one at the time following the instructions):

go to your root git folder

git fetch origin
git fetch upstream
git remote prune upstream
git remote prune origin
/// FIRST TIME YOU RUN THIS SCRIPT
git checkout -b master upstream/master
git push origin master

on Github, in your repository administration, change the default to 'master'

git push origin :cvshead
git branch -d cvshead
/// END OF FIRST TIME
git remote set-head origin -a
git remote set-head upstream -a
/// OTHER TIME - FOR YOUR OTHER GIT MOODLE FOLDERS
git checkout -b master upstream/master
git branch -d cvshead
/// END OF OTHER TIME

check .git/config that there is no references to 'cvshead', if there are replace with 'master'

optional:
update your update script ('cvshead' => 'master')

To know about your branches (the current branch is marked with an asterix)

git branch -a

For any help

git any_command --help

Documentation