making the switch to git (pt. 2)

I used to keep a lot of personal stuff in ~/svn, like my RPG notes, dotfiles for various apps, and some of the stupid little things I stick in ~/bin. I converted that to git about a month ago, and it went just fine. A little later, John and I decided we’d switch svn.codesimply.com to git, and I ran into an annoying problem.

When we first created that repository (or converted things to it), we had everything organized like this:

/exporter/trunk
/exporter/branches
/exporter/tags
/rubric/trunk
/rubric/branches
/rubric/tags

This was mildly annoying, since git-svnimport expects one Subversion repository per project, with the trunk/branches/tags structure at the top level. Converting these wasn’t hard, though, with commands looking something like this:

git svnimport -A authors -i -C git/$project
  -t projects/$project/tags
  -T projects/$project/trunk
  file:///Users/rjbs/vcs/svn/

(I didn’t import branches, as I think only one or two projects had ever branched, and not very interestingly.) The larger problem was that many projects had been renamed. For example, exporter had been renamed to Sub-Exporter and rubric to Rubric. I was baffled about how to deal with this problem. Importing everything from the old name and then from the new name didn’t preserve the history, because somewhere in there a transaction would delete all the old files and create new ones.

I asked around for help, posting to the git list, asking on #git, and poking at people I knew who had a clue. None of this helped very much, although mugwump suggested git-filter-branch, and rafl suggested a similar tool in cogito. Then rafl gave me a link to an article about this problem, which looked quite relevant. The problem was that it was not a 100% step by step solution, and I was really not interested in spending much brainpower thinking about how to apply that solution to my problem. Switching to git is, for me, a way to get a better tool, and not something I wanted to spend any real brain time on.

“Good grief,” I thought to myself, “all I really want to do is import the two sets of changes, skipping the one stupid renaming transaction! Is that so hard?” Of course, as is often the case, yelling my problems out loud made me realize how easy they would be to resolve.

Almost all of the renaming occurred in a block of transactions spanning, let’s say, 100 to 120. I just had to run this for each project:

git svnimport -A authors -i -C git/$new_name
  -t projects/$old_name/tags
  -T projects/$old_name/trunk
  -l 99
  file:///Users/rjbs/vcs/svn/

git svnimport -A authors -i -C git/$new_name
  -t projects/$new_name/tags
  -T projects/$new_name/trunk
  -s 121
  file:///Users/rjbs/vcs/svn/

It imported all the history up to the rename, from the old names. Then, picking up after the rename, it imported all the new history. For a few projects, which were renamed later (due to mistakes during The Great Renaming), I reran the script with alternate values for -l and -s. It was really easy.

I’ve gotten everything converted now, save for Mixin-ExtraFields-Param and a few Kwiki plugins. I think the plugins will be no problem, but MEP has been givng me grief. If I can’t make it just work today, I’ll import it without history, and then I’ll be done!

Starting a read-only git daemon was really easy. I made a new service for daemontools to run, and it has a one-line definition. I’ll probably install gitweb later, but for now I’m ready to start doing all my codesimply coding, simply, with git.

Written on August 12, 2007
git   subversion