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svn2git

svn2git is a tiny utility for migrating projects from Subversion to Git while keeping the trunk, branches and tags where they should be. It uses git-svn to clone an svn repository and does some clean-up to make sure branches and tags are imported in a meaningful way, and that the code checked into master ends up being what's currently in your svn trunk rather than whichever svn branch your last commit was in.

Examples

Say I have this code in svn:

trunk
  ...
branches
  1.x
  2.x
tags
  1.0.0
  1.0.1
  1.0.2
  1.1.0
  2.0.0

git-svn will go through the commit history to build a new git repo. It will import all branches and tags as remote svn branches, whereas what you really want is git-native local branches and git tag objects. So after importing this project I'll get:

$ git branch
* master
$ git branch -a
* master
  1.x
  2.x
  tags/1.0.0
  tags/1.0.1
  tags/1.0.2
  tags/1.1.0
  tags/2.0.0
  trunk
$ git tag -l
[ empty ]

After svn2git is done with your project, you'll get this instead:

$ git branch
* master
  1.x
  2.x
$ git tag -l
  1.0.0
  1.0.1
  1.0.2
  1.1.0
  2.0.0

Finally, it makes sure the HEAD of master is the same as the current trunk of the svn repo.

Installation

Make sure you have git, git-svn, and ruby installed. svn2git is a ruby wrapper around git's native SVN support through git-svn. It is possible to have git installed without git-svn installed, so please do verify that you can run $ git svn successfully. For a Debian-based system, the installation of the prerequisites would like like:

$ sudo apt-get install git-core git-svn ruby rubygems

Once you have the necessary software your system, you can install svn2git through rubygems, which will add the svn2git command to your PATH.

$ sudo gem install svn2git

Usage

Initial Conversion

There are several ways you can create a git repo from an existing svn repo. The differentiating factor is the svn repo layout. Below is an enumerated listing of the varying supported layouts and the proper way to create a git repo from a svn repo in the specified layout.

  1. The svn repo is in the standard layout of (trunk, branches, tags) at the root level of the repo.

    $ svn2git http://svn.example.com/path/to/repo
    
  2. The svn repo is NOT in standard layout and has only a trunk and tags at the root level of the repo.

    $ svn2git http://svn.example.com/path/to/repo --trunk dev --tags rel --nobranches
    
  3. The svn repo is NOT in standard layout and has only a trunk at the root level of the repo.

    $ svn2git http://svn.example.com/path/to/repo --trunk trunk --nobranches --notags
    
  4. The svn repo is NOT in standard layout and has no trunk, branches, or tags at the root level of the repo. Instead the root level of the repo is equivalent to the trunk and there are no tags or branches.

    $ svn2git http://svn.example.com/path/to/repo --rootistrunk
    
  5. The svn repo is in the standard layout but you want to exclude the massive doc directory and the backup files you once accidently added.

    $ svn2git http://svn.example.com/path/to/repo --exclude doc --exclude '.*~$'
    
  6. The svn repo actually tracks several projects and you only want to migrate one of them.

    $ svn2git http://svn.example.com/path/to/repo/nested_project --no-minimize-url
    
  7. The svn repo is password protected.

    $ svn2git http://svn.example.com/path/to/repo --username <<user_with_perms>>
    
  8. You need to migrate starting at a specific svn revision number.

    $ svn2git http://svn.example.com/path/to/repo --revision <<starting_revision_number>>
    
  9. You need to migrate starting at a specific svn revision number, ending at a specific revision number.

    $ svn2git http://svn.example.com/path/to/repo --revision <<starting_revision_number>>:<<ending_revision_number>>
    

The above will create a git repository in the current directory with the git version of the svn repository. Hence, you need to make a directory that you want your new git repo to exist in, change into it and then run one of the above commands. Note that in the above cases the trunk, branches, tags options are simply folder names relative to the provided repo path. For example if you specified trunk=foo branches=bar and tags=foobar it would be referencing http://svn.example.com/path/to/repo/foo as your trunk, and so on. However, in case 4 it references the root of the repo as trunk.

Repository Updates

As of svn2git 2.0 there is a new feature to pull in the latest changes from SVN into your git repository created with svn2git. This is a one way sync, but allows you to use svn2git as a mirroring tool for your SVN repositories.

The command to call is:

    $ cd <EXISTING_REPO> && svn2git --rebase

Authors

To convert all your svn authors to git format, create a file somewhere on your system with the list of conversions to make, one per line, for example:

jcoglan = James Coglan <jcoglan@never-you-mind.com>
stnick = Santa Claus <nicholas@lapland.com>

Then pass an +authors+ option to +svn2git+ pointing to your file:

$ svn2git http://svn.example.com/path/to/repo --authors ~/authors.txt

Alternatively, you can place the authors file into ~/.svn2git/authors and svn2git will load it out of there. This allows you to build up one authors file for all your projects and have it loaded for each repository that you migrate.

If you need a jump start on figuring out what users made changes in your svn repositories the following command sequence might help. It grabs all the logs from the svn repository, pulls out all the names from the commits, sorts them, and then reduces the list to only unique names. So, in the end it outputs a list of usernames of the people that made commits to the svn repository which name on its own line. This would allow you to easily redirect the output of this command sequence to ~/.svn2git/authors and have a very good starting point for your mapping.

$ svn log | grep -E "r[0-9]+ \| .+ \|" | awk '{print $3}' | sort | uniq

Debugging

If you're having problems with converting your repository and you're not sure why, try turning on verbose logging. This will print out more information from the underlying git-svn process.

You can turn on verbose logging with the '-v' or '--verbose' flags, like so:

$ svn2git http://svn.yoursite.com/path/to/repo --verbose

FAQ

  1. Why don't the tags show up in the master branch?

    The tags won't show up in the master branch because the tags are actually tied to the commits that were created in svn when the user made the tag. Those commits are the first (head) commit of branch in svn that is associated with that tag. If you want to see all the branches and tags and their relationships in gitk you can run the following: gitk --all

    For further details please refer to FAQ #2.

  2. Why don't you reference the parent of the tag commits instead?

    In svn you are forced to create what are known in git as annotated tags. It just so happens that svn annotated tags allow you to commit change sets along with the tagging action. This means that the svn annotated tag is a bit more complex then just an annotated tag it is a commit which is treated as an annotated tag. Hence, for there to be a true 1-to-1 mapping between git and svn we have to transfer over the svn commit which acts as an annotated tag and then tag that commit in git using an annotated tag.

    If we were to reference the parent of this svn tagged commit there could potentially be situations where a developer would checkout a tag in git and the resulting code base would be different than if they checked out that very same tag in the original svn repo. This is only due to the fact that the svn tags allow changesets in them, making them not just annotated tags.

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