git-annex/doc/internals/git-remote-annex.mdwn
Joey Hess 3a38520aac
avoid interrupted push leaving remote without a manifest
Added a backup manifest key, which is used if the main manifest key is
not present. When uploading a new Manifest, it makes sure that it never
drops one key except when the other key is present.

It's entirely possible for the two manifest keys to get out of sync, due
to races. The main one wins when it's present, it is possible for the
main one being dropped to expose the backup one, which has a different
push recorded.
2024-05-20 15:41:09 -04:00

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Markdown

The [[git-remote-annex|/git-remote-annex]] command allows pushing a git
repository to a special remote, and later cloning from it.
This adds two new key types to git-annex, GITMANIFEST and a GITBUNDLE.
GITMANIFEST--$UUID is the manifest for a git repository stored in the
git-annex repository with that UUID. When that is not present,
GITMANIFEST--$UUID.bak is a backup copy that can be used instead.
GITBUNDLE--$UUID-$sha256 is a git bundle.
# format of the manifest file
An ordered list of bundle keys, one per line.
Additionally, there may be bundle keys that are prefixed with "-".
These keys are not part of the current content of the git remote
and are in the process of being deleted.
(Lines end with unix `"\n"`, not `"\r\n"`.)
# exporttree=yes remotes
In an exporttree=yes remote, the GITMANIFEST and GITBUNDLE objects are
stored in the remote, under the `.git/annex/objects/` path.
# multiple special remotes in the same place
It's possible for multiple special remotes to point to the same
object storage.
This is why the UUID of the special remote is included in the GITMANIFEST
key, and in the annex:: uri.
# manually cloning from these files
If you are unable to use git-annex and need to clone a git repository
stored in such a special remote, this procedure will work:
* Find and download the GITMANIFEST
* Download each listed GITBUNDLE
* `git fetch` from each new bundle in order.
(Note that later bundles can update refs from the versions in previous
bundles.)
When the special remote is encrypted, the GITMANIFEST and GITBUNDLE will
also be encrypted. To decrypt those manually, see this
[[fairly simple shell script using standard tools|tips/Decrypting_files_in_special_remotes_without_git-annex]].