Just to make sure I understand the situation, you have a git repository which is accessible via a protocol that
apt will understand, like
ftp, which contains
.deb packages which you would like to serve over the network as a remote repository.
This wont be terribly difficult because it seems like you already have the transfer mechanism in place. All that remains is to generate the meta-data which identifies your folder as a repository which aptitude expects to find.
Install the package
Then run the following commands:
dpkg-scanpackages . /dev/null | gzip -9c > Packages.gz
Don't worry about the
/dev/null too much.
dpkg-scanpackages expects an override file to be passed which you don't need to bother with so you're passing it an empty file.
Then on your client all you need to do is edit your
dpkg-scanpackages will have to be run every time you update a package and how you accomplish that will depend on what works best for you. A
cron job running every few minutes, a custom service using
inotify and the
inotifywait command, or just a simple wrapper script to commit your changes run the command.