Does this mean I can use the overlay2 driver with docker instead of the ZFS one? I've had many people tell me this was possible in the past when it definitely wasn't.
The performance and reliability of the ZFS driver leaves lots to be desired. The last time I ran Docker on a ZFS partition I actually used a zvol formatted ext4 just to avoid these issues.
No wonder: it calls the zfs(1) tool and parses its output to do its work. Again. and again. and again.
Thing is, https://github.com/moby/moby/blob/670bc0a46c4ca03b75f1e72f73... is using https://github.com/mistifyio/go-zfs which features code like `out, err := zfsOutput("get", "-H", key, d.Name)` (Source: https://github.com/mistifyio/go-zfs/blob/master/zfs.go#L315) to get a single zfs property.
Somebody chose to use a library as abstraction that looks good but is implemented as a MVP (nothing wrong with that). "In the future, we hope to work directly with libzfs" should have raised an alarm somewhere, though.
Looks like the answer to that is "yes, but be careful as some are kind of dodgy". :/
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Oh, that library bills itself as "Simple wrappers for ZFS command line tools", rather than as a ZFS interface.
Wonder why the Moby project picked that one then? Maybe a case of "it was the best choice at the time".