Faults from cell DB missing in GET /servers/detail

[Ivaylo Mitev]

Description
===========
Field `fault` is empty in the response of API GET /servers/detail if the instance (hence instace_faults DB entry) is in nova cell DB.
Unlike that, for API /servers/:id fault is retrieved correctly no matter in which nova cell the instance belongs.

Steps to reproduce
==================
* Ensure two servers/instances with faults (i.e. entry in instance_faults DB table) in different Nova cells
* Invoke REST API call GET /servers/detail

Expected result
===============
The result entries for both instances should contain value for `fault` field.

Actual result
=============
`fault` is initialized only for the instance in cell 0. For the other one it's empty.

Environment
===========
1. Exact version of OpenStack you are running. See the following
Queens

2. Which hypervisor did you use?
VMware 6.5

[Matt Riedemann (mriedem)]

The fault is only exposed if the server status is ERROR or DELETED. For the server that is not showing the fault in the response (from cell1) what is the status of that server?

[Matt Riedemann (mriedem)]

I wonder if there was a regression with this:

https://github.com/openstack/nova/blob/2f0f8b8cf13b7441ce6a7a524b33d30d40f1d468/nova/compute/instance_list.py#L172

[Ivaylo Mitev (imitev)]

Hm, it could be that. We've found another fix and I suggested a change here: https://review.opendev.org/#/c/699176/.