git-svn-helpers is a collection of command line tools that greatly simplify using git for svn repositories.

Its main goal is to make setting up a local git repository following an existing svn checkout a 'no-brainer'.

It also addresses using a single git-svn repository for working on multiple checkouts of (usually) different branches and switching between them.

Basic usage

Executive summary:

> cd path/to/svn/repo
> gitify init

Perform local changes and commit them to git. When ready to push your changes:

> gitify push

To update your working directory with upstream changes:

> gitify update

gitify will take care to keep your git and svn repository in sync and do its best to avoid conflicts when updating.

Sample session

Here's a sample session:

> cd /tmp
> svn co https://svn.plone.org/svn/plone/plone.app.form/branches/1.1 plone.app.form
A    1.1/setup.py
...
Checked out revision 27228.
> cd plone.app.form
> gitify init
No git repository found in /Users/tomster/.gitcache/.
Initiating cloning into cache.
Analyzing svn log...
Cloning https://svn.plone.org/svn/plone/plone.app.form/ from r10593:34543 into /Users/tomster/.gitcache/
Initialized empty Git repository in /Users/tomster/Development/gitcache/plone.app.form/.git/
...
Git branch 'local/1.1' is now following svn branch '1.1':
# On branch local/1.1
nothing to commit (working directory clean)
> git branch
* local/1.1
  master

Points to note:

• gitify limited the cloning to the revisions found in the svn log of the package root (here https://svn.plone.org/svn/plone/plone.app.form/). A big time saver, especially on large repositories (such as plone.collective)
• gitify created a local branch local/1.1 that follows the (remote) svn branch 1.1 and switched to it
• gitify assumed that the name of the package is the name of the directory it was called from (in this case plone.app.form) as it refuses to guess

Multiple check-outs of the same package

In practice you will often work with different local copies of a given repository, i.e. on trunk and on a feature branch. That's when the .gitcache directory created above comes in handy. Let's move our previous checkout out of the way and create a maintenance checkout that follows trunk:

> cd ..
> mkdir feature-branch
> mv plone.app.form feature-branch/
> mkdir maintenance
> cd maintenance/
> svn co https://svn.plone.org/svn/plone/plone.app.form/trunk plone.app.form
A    plone.app.form/setup.py
...
 U   plone.app.form
Checked out revision 27228.

What happens if we run gitify here?:

> cd plone.app.form/
> gitify init
Updating existing cache:
fetching /Users/tomster/.gitcache/plone.app.form
Done. 1 packages updated.
Git branch 'local/trunk' is now following svn branch 'trunk':
# On branch local/trunk
nothing to commit (working directory clean)

Notice, that this operation went much faster, as we now have used the existing git repository in the cache directory, thus avoiding the slow and network intensive clone operation.

This can be further evidenced by looking at the available local branches now. Notice how the git repository contains both trunk and the 1.1 branch:

> git branch
  local/1.1
* local/trunk
  master

Switching branches

If the svn repository switches to another branch (i.e. due to a change in svn:externals or in a buildout source) the branch git is on differs from the current svn branch. To remedy this you can either manually switch git or just re-run gitify init:

> svn info
URL: https://svn.plone.org/svn/plone/plone.app.form/trunk

> git branch
  local/1.1
* local/trunk
  master

If we switch the svn branch, git initially doesn't catch the change and the branches differ:

> svn switch https://svn.plone.org/svn/plone/plone.app.form/branches/1.1
> svn info
URL: https://svn.plone.org/svn/plone/plone.app.form/branches/1.1

> git branch
  local/1.1
* local/trunk
  master

After re-running gitify init they are the same again:

> git branch
* local/1.1
  local/trunk
  master

Keeping the cache up-to-date

Of course, once you introduce a cache you need to keep it up-to-date. git-svn provides the fetch command for this purpose. In practice it is cumbersome to update each package manually, though. Therefore we provide our own fetch command which can update multiple packages at once using wildcards, like so:

> gitify fetch plone*
fetching /Users/tomster/.gitcache/plone.app.form
fetching /Users/tomster/.gitcache/plone.pony
fetching /Users/tomster/.gitcache/plonenext
Done. 3 packages updated.

You can pass the -v option to see the output of the git-svn fetch commands. If you don't provide a package all packages will be updated.

Note, that the our fetch command never touches any working copy, only the cache. Is primarily intended to be run as a maintenance command, i.e. via crontab to keep the local cache 'fresh'.

Keeping git and svn in sync

Since the local filesystem is both a git repository, as well as a svn check-out at the same time (IOW we have both .git and .svn floating around) they should be kept in sync as closely as possible. By design, this can only happen, when we have online access to the svn repository. Therefore it is best performed when committing back to svn. The way this is achieved manually is to first dcommit and then perform a svn up --force command (the --force is necessary so that svn won't be bothered by any new files that have been committed). gitify push provides a convenience command that performs this for you:

> gitify push -v
Committing to https://svn.plone.org/svn/plone/plone.app.form/branches/1.1 ...
At revision 27229.
INFO: Pushed local changes to svn.
> svn st
<BLANKLINE>

Installation

Simply use easy_install, optionally with virtualenv:

> easy_install git-svn-helpers

Requirements

git-svn-helpers requires that git (with subversion support a.k.a git-svn) is already installed.

TODO

• add support for custom svn layout