Importing git history into a new svn repository

So the management has finally approved your project, and has asked you to start working on it. Heh ... little do they know that you'd already been working on it, and have a nice prototype working, and it's all saved on your local git repository. But your company is not as cool as you are - it has it's own svn repository, and now you have to import your code into it, history and all.

Here is the git tree, as you have developed it:



.. and your svn repository looks similar to this -

$ svn co <svn repo url>
Checked out revision 0.

$ cd <svnrepo>

$ mkdir tags trunk branches

$ svn add *
A         branches
A         tags
A         trunk

$ svn commit -m "initial directory structure"
Adding         branches
Adding         tags
Adding         trunk

Committed revision 1.

Now you could copy all the files from the git repository into trunk, and commit it. But that is really not the way it should be. For one - no one will know the reason for *anything* in this repository before the big bang. Also, there might have been legitimate reasons for people to branch out from some earlier state of the code, but now no one will even know.

Fortunately, a mail on the kerneltrap archives tells us how we can export a git repository, along with all it's history, into an svn repository.

(from http://kerneltrap.org/mailarchive/git/2008/10/26/3815034)

From: Björn <B.Steinbrink@...>

...
...

This should do and uses a graft to simplify the process a bit:

Initialize git-svn:

git svn init -s --prefix=svn/ https://svn/svn/SANDBOX/warren/test2

The --prefix gives you remote tracking branches like "svn/trunk" which
is nice because you don't get ambiguous names if you call your local
branch just "trunk" then. And -s is a shortcut for the standard
trunk/tags/branches layout.

Fetch the initial stuff from svn:

git svn fetch

Now look up the hash of your root commit (should show a single commit):

git rev-list --parents master | grep '^.\{40\}$'

Then get the hash of the empty trunk commit:

git rev-parse svn/trunk

Create the graft:

echo <root-commit-hash> <svn-trunk-commit-hash>  >> .git/info/grafts

Now, "gitk" should show svn/trunk as the first commit on which your
master branch is based.

Make the graft permanent:

git filter-branch -- ^svn/trunk --all

Drop the graft:

rm .git/info/grafts

gitk should still show svn/trunk in the ancestry of master

Linearize your history on top of trunk:

git svn rebase

And now git svn dcommit -n should tell you that it is going to commit
to trunk.

If you check your svn repository log, it will look like this.


All the history, nice and linearised for svn.

Keep in mind though, that this method is lossy. All the branches have been linearised, and you can no longer "check them out" in the original git repository. Apart from that, things work just fine, and you can continue to commit in your local git repository, and push to svn as and when needed.

On git, gitosis, and python issues on Windows Vista

Some browsing, debugging, and IRC chats later, I have managed to set up a git repository on Windows Vista using cygwin, with a few unexpected hiccups. I will try to repeat the process on a virgin setup to come up with a more authoritative flowchart of how to go about things. For now, I'll just list down the issues I faced.

I used gitosis to host git repositories over ssh. It's pretty elegant, really. Administering gitosis is limited to managing a configuration file and user keys, which itself themselves are in a gitosis hosted git repository. Neat.

These two articles

• installing ssh on cygwin
  
• hosting a gitosis repository
  

cover everything you need to do to host git repos. The first link should be straightforward. However, since the second link is for linux users, there are a few deviations for windows. Try to follow the link, if you face difficulties, refer to the tips below.

Installing gitosis

Log in to an administrator account. Do a

cd ~/src
git clone git://eagain.net/gitosis.git
cd gitosis
python setup.py install

If the last command fails thusly

Traceback (most recent call last):
File "setup.py", line 2, in ?
from setuptools import setup, find_packages
ImportError: No module named setuptools

you may need setuptools from here. Scroll to the bottom, download an egg, and do

sh setuptools-0.6c9-py2.5.egg

Repeat the last step. After you have installed gitosis successfully, run the following command

chmod +r /usr/lib/python2.5/ -R

This was the first wtf. The downloaded egg we just installed gets installed with administrator ACLs, the above command ensures that everyone has access to the downloaded eggs.

Setting up gitosis

You need to add the git repository user `git' the windows way (the adduser command in the second link will not work). Once you've done that, make sure you've run the following commands

# in the new 'git' user's account
ssh-user-config

# from the admin account
# (domain users need to add '-d domain_name' to the mk* commands)
mkpasswd.exe -l > /etc/passwd
mkgroup.exe -l > /etc/group

Also, the command

sudo -H -u git gitosis-init < /tmp/id_rsa.pub

will need to be run as

# git user's account
gitosis-init < /tmp/id_rsa.pub

Of course, this assumes that you've copied your key to the /tmp folder.

The rest of the write-up should be fine, except for one thing. When you try to `git commit' you repo configuration, you may see an error like :

Counting objects: 5, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 307 bytes, done.
Total 3 (delta 1), reused 0 (delta 0)
To git@localhost:gitosis-admin.git
989f371..0616ebb master -> master
: invalid optione: line 2: set: -
set: usage: set [--abefhkmnptuvxBCHP] [-o option] [arg ...]

Second wtf. Damn those pesky windows newlines. Do a

# `git' user's account
dos2unix ~/repositories/gitosis-admin.git/hooks/post-update

and you should be good to go.

This should do it. If you still run into problems, let me know. If you find solutions to them, post them up so that I may link to you. And when you do have a git repository up, give me the url to fork from :)

Edit: fixed grammar