Git-backup - Backup set of Git repositories & just files; efficiently

Author:	Kirill Smelkov <[email protected]>
Date:	2015 Aug 31

This program backups files and set of bare Git repositories into one Git repository. Files are copied to blobs and then added to tree under certain place, and for Git repositories, all reachable objects are pulled in with maintaining index which remembers reference -> sha1 for all pulled repositories.

This allows to leverage Git's good data deduplication ability, especially for cases when there are many hosted repositories which are forks of each other, and for backup to have history and be otherwise managed as a usual Git repository. In particular it is possible to use standard git pull/push to synchronize backups in several places.

Backup workflow is:

1. create backup repository:

   $ mkdir backup
   $ cd backup
   $ git init         # both bare and non-bare possible
   

2. pull files and Git repositories into backup repository:

   $ git-backup pull dir1:prefix1 dir2:prefix2 ...
   

   This will pull bare Git repositories & just files from dir1 into backup under prefix1, from dir2 into backup prefix prefix2, etc...

3. restore files and Git repositories from backup:

   $ git-backup restore <backup-state-sha1> prefix1:dir1
   

   Restore Git repositories & just files from backup prefix1 into dir1, from backup prefix2 into dir2, etc...

   Backup state to restore is taken from <backup-state-sha1> which is sha1 or ref pointing to backup repository state.

4. backup repository itself can be managed with Git. In particular it can be synchronized between several places with standard git pull/push, be repacked, etc:

   $ git push ...
   $ git pull ...
   

Please see git-backup.go source with technical overview on how it works.

We also provide convenience program to pull/restore backup data for a GitLab instance into/from git-backup managed repository. See contrib/gitlab-backup for details.