Docker snap bug? storage-driver errors

snap
1

Hi,
I tried installing docker via snap on CentOS 7 but the docker service failed to start due to incorrect storage-driver.

As specified here: https://docs.docker.com/storage/storagedriver/select-storage-driver/

“devicemapper is supported, but requires direct-lvm for production environments, because loopback-lvm, while zero-configuration, has very poor performance. devicemapper was the recommended storage driver for CentOS and RHEL, as their kernel version did not support overlay2. However, current versions of CentOS and RHEL now have support for overlay2, which is now the recommended driver.”

I tried to change from aufs to overlay2 by running vi /var/snap/docker/current/config/daemon.json and change the “aufs” to “overlay2”.

But then it failed with error: “Error starting daemon: error initial izing graphdriver: overlay2: the backing xfs filesystem is formatted without d_t ype support, which leads to incorrect behavior. Reformat the filesystem with fty pe=1 to enable d_type support. Backing filesystems without d_type support are no t supported.”

Does this is a bug with the docker snap?

Thanks

2

Hi @ijohnson, maybe you have the answer?

Thanks

3

@tianon, can you take a look at this? Not sure if this is still an issue or not.

4

Yes, in my experience this is unfortunately what “life with Docker on CentOS” ends up looking like (partly due to their old kernels, and partly due to some default choices, as seen in the XFS error coming back from Docker).

There’s not really anything we can do in the Snap itself to fix this (short of removing the default storage-driver value, but in this case I think that would probably lead to a less-than-optimal devmapper setup instead, so I think we’re better off setting the default to overlay2 and having folks who need a different value configure it themselves, because there’s always a trade-off).

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