Set correct permissions for users in a group automatically

[Marcelo00]

In a shared cache directory set up, dvc fails to set the correct permissions for the folders in the cache directory. For instance, a user X executes a dvc command - e.g dvc pull which sets the permission of a directory to rwxr-xr-x. A different user Y who is in the same group and is working with the same cache directory, is not able to delete files in this specific directory as the permission forbids it. Therefore, the user Y gets a Operation is not permitted error.

With this context, a additional parameter in the the cache config like git config core.sharedRepository group (https://git-scm.com/docs/git-config) which addresses this problem, may a suitable solution for a working shared cache directory set up.

For a more detailed overview see the conversation in the discord channel: https://discordapp.com/channels/485586884165107732/485596304961962003

[BoysFight]

I have this problem too. I tried setfacl to let other user have the access to the files, but it still can not work.

[efiop]

@BoysFight Have you tried setting umask to 0(or 002) ? Theoretically It should be a viable workaround, as it will make all files and directories created by dvc be accessble by other users in your group. Though you'd need to chmod your already existing files first to make it work. But in any case, this should be supported by dvc itself too, same as git does with it's core.sharedRepository, so I've prepared a patch for cache.shared option that does precisely that. Right now I'm figuring out details for some optimizations in our code that don't play nicely with that shared mode. Should be ready soon, so stay tuned! 🙂

[BoysFight]

@efiop I tried, but i got "ERROR: failed to obtain data status - [Errno 1] Operation not permitted: {dvcCacheFilePath}".
As a workaround, i modify the owner of "/usr/bin/dvc" and set the suid flag.

[efiop]

Oh, @BoysFight , that is a neat workaround indeed! Does everything work properly after setting the suid flag? Btw, I've pushed dvc config cache.shared group support to my fork. Instructions on how to try it out are available here https://discordapp.com/channels/485586884165107732/485596304961962003/601402500779737103 , please feel free to try it out and be sure to let us know if it worked for you or not.

@efiop , take a loot at this issue: #2214

It might be helpful and probably fix it.