File Locking

risk danger olson edited this page Mar 1, 2017 · 2 revisions

Git LFS v2.0.0 includes an early release of File Locking. File Locking lets developers lock files they are updating to prevent other users from updating them at the same time. Concurrent edits in Git repositories will lead to merge conflicts, which are very difficult to resolve in large binary files.

Tracking Lockable files

Git has built-in tools for resolving merge conflicts in text files (such as source code, documentation, etc). The first step to using File Locking is to define what file types need the extra overhead. The git lfs track command includes a --lockable flag. The following command will store JPG files in LFS, and mark them as lockable:

$ git lfs track "*.jpg" --lockable

This adds the following line to your .gitattributes file:

*.jpg filter=lfs diff=lfs merge=lfs -text lockable

If you'd like to register a file type as lockable, without using LFS, you can edit the .gitattributes file directly:

*.yml lockable

Once file patterns in .gitattributes are lockable, Git LFS will make them readonly on the local file system automatically. This prevents users from accidentally editing a file without locking it first.

Managing Locked Files

When you are ready to edit files, run the lock command:

$ git lfs lock images/foo.jpg
Locked images/foo.jpg

This registers the file as locked in your name on the server. You can view this with the locks command.

$ git lfs locks
images/bar.jpg  jane   ID:123
images/foo.jpg  alice  ID:456

The file will also be ready for you to edit and push locally. If at any time you decide you don't need the lock, you can remove it by passing the path or ID to the unlock command.

$ git lfs unlock images/foo.jpg
$ git lfs unlock --id=456

You can also unlock someone else's file with the --force flag:

$ git lfs unlock images/foo.jpg --force

Note: Different LFS server implementations may have different permissions. Some may require admin privileges to unlock someone else's lock, for example.

Pushing Your Changes

Git LFS will verify that you're not modifying a file locked by another user when pushing. Since File Locking is an early release, and few LFS servers implement the API, Git LFS won't halt your push if it cannot verify locked files. You'll see a message like this:

$ git lfs push origin master --all
Remote "origin" does not support the LFS locking API. Consider disabling it with:
  $ git config 'lfs.http://git-server.com/user/test.locksverify' false
Git LFS: (0 of 0 files, 7 skipped) 0 B / 0 B, 879.11 KB skipped
$ git lfs push origin master --all
Locking support detected on remote "origin". Consider enabling it with:
  $ git config 'lfs.http://git-server.com/user/repo.locksverify' true
Git LFS: (0 of 0 files, 7 skipped) 0 B / 0 B, 879.11 KB skipped
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