Using Git (and GitHub) with Subversion Mirroring for WordPress Plugin Development

by Kaspars Dambis -- konstruktors.com / @konstruktors

We'll assume that your plugin is already hosted on the official WordPress plugin Subversion repository, and we'll use the Easy Digital Downloads plugin as an example.

First, we need to get the revision number of the first commit to the WordPress Subversion repository, because otherwise Git will try to go through all 100000+ commits in order to find it.
```
 $ svn log http://plugins.svn.wordpress.org/easy-digital-downloads/
```
It is the last commit revision you seen on the screen:
```
 ------------------------------------------------------------------------
 r529177 | plugin-master | 2012-04-09 19:36:16 +0200 (Mon, 09 Apr 2012) | 1 line

 adding easy-digital-downloads by mordauk
 ------------------------------------------------------------------------
```
In this case it is r529177. You can also use the official WordPress Trac browser to determine the first revision number.
Now, create a local Git repository and import the first commit from the SVN repository:
```
 $ git svn clone --no-minimize-url -s -r529177 http://plugins.svn.wordpress.org/easy-digital-downloads/
```
which returns the following:
```
 Initialized empty Git repository in /Users/kaspars/svn2git/easy-digital-downloads/.git/
 r529177 = e18c66d09d77e4d8a923f2f300f73606791071e1 (refs/remotes/trunk)
 Checked out HEAD:
   http://plugins.svn.wordpress.org/easy-digital-downloads/trunk r529177
```
Notice the --no-minimize-url flag which is required to stop git svn clone from moving into the base folder of the remote SVN repository and going through all plugins (see git-svn docs). We also use the -s flag which is a shorthand way of setting trunk, tags, branches as the relative paths, which is the Subversion default (from git-svn docs).
Finally, move inside the newly created Git repository:
```
 $ cd easy-digital-downloads
```
and fetch all the other commits from the SVN repo:
```
 $ git svn fetch
```
This step will take hours (!), so you can use the GIT_TRACE=2 flag before the the command to see a verbose output:
```
 $ GIT_TRACE=2 git svn fetch
```
Once this process is finished you have a complete Git commit tree of the project. The final step is to move the SVN HEAD (files from /trunk) into our Git master (I assume), which is done using:
```
 $ git svn rebase
```
Now you should see all the latest plugin files in your local repository.

Inspecting the Newly Cloned Repository

Let's look at all the branches that were created:

$ git branch -a

returns a list of all the available branches:

* master
  remotes/tags/1.0.1.1
  remotes/tags/1.0.1.2
  remotes/tags/1.0.1.3
  remotes/tags/1.0.1.4
  ...
  remotes/tags/1.1.8
  remotes/tags/1.2
  remotes/tags/1.2.1
  remotes/tags/1.2.1.1
  remotes/trunk

If we look inside .git/config in our newly created Git repository:

[core]
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true
        ignorecase = true
        precomposeunicode = false
[svn-remote "svn"]
        url = http://plugins.svn.wordpress.org/easy-digital-downloads
        fetch = trunk:refs/remotes/trunk
        branches = branches/*:refs/remotes/*
        tags = tags/*:refs/remotes/tags/*

we can see that Git has automatically selected trunk as the destination for git svn dcommit which pushes all your changes back to the WordPress repository.

Publishing Changes to GitHub and WordPress Subversion Repository

Let's create a new GitHub repository which we'll use as our main repository for our plugin from now on:

Once you have created the repository, simply add it as a remote origin of our local Git repository:

$ git remote add origin [email protected]:kasparsd/wordpress-svn2git-sample.git

and then push our local repository to GitHub:

$ git push -u origin master

Now your GitHub repository should contain all your plugin files as well as all the revision history carried over from the Subversion repository.

Working with the Plugin

Now let's assume that we want to create a new release of the plugin in order to invite the plugin users to report bugs and get involved on GitHub. For that we need to edit the copy of readme.txt and bump the version number of the plugin.

Once we have made the changes, we can check the status of our local Git repository:

$ git status

# On branch master
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#	modified:   easy-digital-downloads.php
#	modified:   readme.txt
#
no changes added to commit (use "git add" and/or "git commit -a")

Let's commit the changes to our local repository:

$ git commit -am "Adding message about moving to GitHub, version bump"

Pushing Changes to GitHub

To publish our local commits to GitHub, we use

$ git push

	[master addb6cf] Adding message about moving to GitHub, version bump
 2 files changed, 12 insertions(+), 1112 deletions(-)
 rewrite readme.txt (99%)

Pushing Changes to WordPress Subversion Repository

Once you have switched to using Git as your version control system, you should always use git svn to publish changes to the SVN repository. Otherwise, you must use

$ git svn rebase

every time before pushing changes to SVN in order to merge changes from the SVN repository into your local Git repo.

If you are not using trunk as a release branch for your plugin, you may safely push all your Git changes to the WordPress repository without worrying about users getting update notices:

$ git svn dcommit

Now, because I don't have write access this particular repository, here is a response that I get when pushing one of my own plugins:

Committing to http://plugins.svn.wordpress.org/widget-context/trunk ...
	M	widget-context.php
Committed r601084
	M	widget-context.php
r601084 = a1c2a2f8f4f98ec5537aef48545e350ff6270f2b (refs/remotes/trunk)
No changes between b6098f5bb1751cc05309093cad1d5d982a964158 and refs/remotes/trunk
Resetting to the latest refs/remotes/trunk