Configuration format for shard->path map
For sharding gitaly will need to be able to map something like this:
Repository.new(shard: 'storage01', path: 'foo/bar.git')
To:
/mnt/st1/repositories/foo/bar.git
In other words, in this example we'd want a map storage01 -> '/mnt/st1/repsitories'
.
How will we pass this configuration into the Gitaly server process? Our current (and only) configuration mechanism is environment variables.