Description

When using graph-drivers, the storage-driver section provides some additional details about the host's "backing" filesystem.

Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false

When using snapshotters, we only list the name of the default snapshotter (which is currently a "global" default, and we don't (yet) allow per-container snapshotters, but this may be something we add in future);

Storage Driver: stargz
  driver-type: io.containerd.snapshotter.v1

The additional information has often proven to be useful when triaging / debugging reported issues, so we should look at bringing (some of) that information back, but we need to look what the best location is to surface;

• When using graph-drivers, the additional information is provided by the graph-driver, and the information shown differs between drivers, which can make sense because for a block-storage driver, the "backing filesystem" is not really relevant.
• Does containerd (and snapshotters) have an API/interface to provide additional information relevant to the snapshotter?
• OTOH, some of that information could be considered "general" information, so perhaps it's fine to collect (and present) it separate from the active (default) snapshotter

Somewhat related; if we support multiple snapshotters (in future), should we provide the list of available snapshotters? Containerd detects support for each snapshotter during startup (but not sure if there's a good way to get the list of snapshotter that can be used); also see #44076