We have a nova spec  which is at the point that it needs some API
user (and operator) feedback on what nova API should be doing when
listing servers and there are down cells (unable to reach the cell DB or
it times out).
tl;dr: the spec proposes to return "shell" instances which have the
server uuid and created_at fields set, and maybe some other fields we
can set, but otherwise a bunch of fields in the server response would be
set to UNKNOWN sentinel values. This would be unversioned, and therefore
could wreak havoc on existing client side code that expects fields like
'config_drive' and 'updated' to be of a certain format.
There are alternatives listed in the spec so please read this over and
provide feedback since this is a pretty major UX change.
Oh, and no pressure, but today is the spec freeze deadline for Rocky.
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