Migration guide from Git Annex to Git LFS

DANGER: Deprecated: Git Annex support has been removed in GitLab Enterprise Edition 9.0 (2017/03/22).

Both Git Annex and Git LFS are tools to manage large files in Git.

History

Git Annex was introduced in GitLab Enterprise Edition 7.8, at a time where Git LFS didn't yet exist. A few months later, GitLab brought support for Git LFS in GitLab 8.2 and is available for both Community and Enterprise editions.

Differences between Git Annex and Git LFS

Some items below are general differences between the two protocols and some are ones that GitLab developed.

Git Annex works only through SSH, whereas Git LFS works both with SSH and HTTPS (SSH support was added in GitLab 8.12).
Annex files are stored in a sub-directory of the normal repositories, whereas LFS files are stored outside of the repositories in a place you can define.
Git Annex requires a more complex setup, but has much more options than Git LFS. You can compare the commands each one offers by running man git-annex and man git-lfs.
Annex files cannot be browsed directly in GitLab's interface, whereas LFS files can.

Migration steps

Since Git Annex files are stored in a sub-directory of the normal repositories (.git/annex/objects) and LFS files are stored outside of the repositories, they are not compatible as they are using a different scheme. Therefore, the migration has to be done manually per repository.

There are basically two steps you need to take in order to migrate from Git Annex to Git LFS.

TL; DR

If you know what you are doing and want to skip the reading, this is what you need to do (we assume you have git-annex enabled in your repository and that you have made backups in case something goes wrong). Fire up a terminal, navigate to your Git repository and:

Disable git-annex:

git annex sync --content
git annex direct
git annex uninit
git annex indirect

Enable git-lfs:

git lfs install
git lfs track <files>
git add .
git commit -m "commit message"
git push

Disabling Git Annex in your repo

Before changing anything, make sure you have a backup of your repository first. There are a couple of ways to do that, but you can simply clone it to another local path and maybe push it to GitLab if you want a remote backup as well. Here you'll find a guide on how to back up a git-annex repository to an external hard drive.

Since Annex files are stored as objects with symlinks and cannot be directly modified, we need to first remove those symlinks.

NOTE: Note: Make sure the you read about the direct mode as it contains useful information that may fit in your use case. Note that annex direct is deprecated in Git Annex version 6, so you may need to upgrade your repository if the server also has Git Annex 6 installed. Read more in the Git Annex troubleshooting tips section.

Backup your repository

cd repository
git annex sync --content
cd ..
git clone repository repository-backup
cd repository-backup
git annex get
cd ..

Use annex direct:

cd repository
git annex direct

The output should be similar to this:

commit
On branch master
Your branch is up-to-date with 'origin/master'.
nothing to commit, working tree clean
ok
direct debian.iso ok
direct  ok

Disable Git Annex with annex uninit:
```
git annex uninit
```
The output should be similar to this:
```
unannex debian.iso ok
Deleted branch git-annex (was 2534d2c).
```
This will unannex every file in the repository, leaving the original files.

Switch back to indirect mode:

git annex indirect

The output should be similar to this:

(merging origin/git-annex into git-annex...)
(recording state in git...)
commit  (recording state in git...)

ok
(recording state in git...)
[master fac3194] commit before switching to indirect mode
 1 file changed, 1 deletion(-)
 delete mode 120000 alpine-virt-3.4.4-x86_64.iso
ok
indirect  ok
ok

At this point, you have two options. Either add, commit and push the files directly back to GitLab or switch to Git LFS. We will tackle the LFS switch in the next section.

Enabling Git LFS in your repo

Git LFS is enabled by default on all GitLab products (GitLab CE, GitLab EE, GitLab.com), therefore, you don't need to do anything server-side.

First, make sure you have git-lfs installed locally:
```
git lfs help
```
If the terminal doesn't prompt you with a full response on git-lfs commands, install the Git LFS client first.
Inside the repository, run the following command to initiate LFS:
```
git lfs install
```
Enable git-lfs for the group of files you want to track. You can track specific files, all files containing the same extension, or an entire directory:
```
git lfs track images/01.png   # per file
git lfs track **/*.png        # per extension
git lfs track images/         # per directory
```
Once you do that, run git status and you'll see .gitattributes added to your repository. It collects all file patterns that you chose to track via git-lfs.
Add the files, commit and push them to GitLab:
```
git add .
git commit -m "commit message"
git push
```
If your remote is set up with HTTP, you will be asked to enter your login credentials. If you have 2FA enabled, make sure to use a personal access token instead of your password.

Removing the Git Annex branches

After the migration finishes successfully, you can remove all git-annex related branches from your repository.

On GitLab, navigate to your project's Repository ➔ Branches and delete all branches created by Git Annex: git-annex, and all under synced/.

You can also do this on the command line with:

git branch -d synced/master
git branch -d synced/git-annex
git push origin :synced/master
git push origin :synced/git-annex
git push origin :git-annex
git remote prune origin

If there are still some Annex objects inside your repository (.git/annex/) or references inside .git/config, run annex uninit again:

git annex uninit