Version controlled South migrations in virtualenv

Question

I have a Django site placed in folder site/. It's under version control. I use South for schema and data migrations for my applications. Site-specific applications are under folder site/ so they are all version-controlled along with their migrations.

I manage a virtualenv to keep third party components dry and safe. I install packages via PyPI. The installed packages' list are frozen in requirements.txt so the they can be easily installed in another environment. The virtualenv is not under VCS. I think it is a good way if virtualenv can be easly deleted and reconstructed at any time. If I need to test my site, for instance, using another version of Python interpreter, simply activate another virtulalenv.

I'd like to use South for third party packages, though. Here comes the problem. Migration scripts stored in the application's folder so they are outside of my site's repository. But I want migration scripts to be under version control so I can run them on different stages as well.

I don't want to version control the whole virtualenv but the migration scripts for third party applications. How can I resolve this conflict? Is there any misconcept in my scenario?

Answer 1

I think it depends a litte bit on your version control system. I recommend to use a sparse tree, one that only manages the migration folders of the various packages. Here I see two alternatives:

1. Make a truly sparse tree for all packages, one that you check out before creating the virtualenv. Then populate the virtualenv, putting stuff into the existing folders.

2. Collect all migrations into a separate repository, with a folder per project/external dependency. Check this out into the virtualenv, and create symlinks, linking from each project to its migration folder.

In either case, I believe you can arrange for the migrations to exist as a separate project, so you can install it with the same process as you install everything else (easy_install/pip/whatever).

Answer 2

The SOUTH_MIGRATION_MODULES setting allows you to put migration modules for specified apps wherever you want them (i.e. inside your project tree).