[nova][dev][ops] server status when compute host is down

melanie witt melwittt at gmail.com
Thu May 23 01:58:34 UTC 2019

Hey all,

I'm looking for feedback around whether we can improve how we show 
server status in server list and server show when the compute host it 
resides on is down.

When a compute host goes down while a server on it was previously 
running, the server status continues to show as ACTIVE in a server list. 
This is because the power state and status is adjusted by a periodic 
task run by nova-compute, so if nova-compute is down, it cannot update 
those states.

So, for an end user, when they do a server list, they see their server 
as ACTIVE when it's actually powered off.

We have another field called 'host_status' available since API 
microversion 2.16 [1] which is controlled by policy and defaults to 
admin, which is capable of showing the server status as UNKNOWN if the 
field is specified, for example:

nova list --fields 

This is cool, but it is only available to admin by default, and it 
requires that the end user adds the field to their CLI command in the 
--fields option.

Question: do people think we should make the server status field reflect 
UNKNOWN as well, if the 'host_status' is UNKNOWN? And if so, should it 
be controlled by policy or no?

Normally, we do not expose compute host details to non-admin in the API 
by default, but I noticed recently that our "down cells" support will 
show server status as UNKNOWN if a server is in a down cell [2]. So I 
wondered if it would be considered OK to show UNKNOWN if a host is down 
we well, without defaulting it to admin-only.

I would really appreciate if people could share their opinion here and 
if consensus is in support, I will move forward with proposing a change 



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