Bug 1562082

Summary:	Can't blacklist all controllers when scaling out computes as running discover_hosts on a nova api node is required
Product:	Red Hat OpenStack	Reporter:	James Slagle <jslagle>
Component:	openstack-tripleo-heat-templates	Assignee:	Rajesh Tailor <ratailor>
Status:	CLOSED ERRATA	QA Contact:	Victor Voronkov <vvoronko>
Severity:	high	Docs Contact:
Priority:	high
Version:	12.0 (Pike)	CC:	lyarwood, mburns, mcornea, ratailor, ravsingh, rhel-osp-director-maint, vvoronko
Target Milestone:	async	Keywords:	Triaged, ZStream
Target Release:	13.0 (Queens)
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	openstack-tripleo-heat-templates-8.2.0-20.el7ost	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1693563 (view as bug list)		Environment:
Last Closed:	2019-04-30 17:27:35 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1684868, 1693563

Description James Slagle 2018-03-29 13:32:16 UTC

There's a report[1] that in OSP12 we can no longer scale out compute
nodes without also running "nova-manage cell_v2 discover_hosts" on the
controllers (or at least a node running nova api).

This is only an issue when scaling out computes while using the blacklist
feature so that no changes are pushed to controllers. Using the blacklist
enables scaling computes without changing any other nodes in your deployment.

I (believe) it's been traditionally well understood in OpenStack that you can
scale out compute nodes without having to also modify/update your control plane
services. But, this no longer seems possible if you must also run
discover_hosts on a node where nova api is running.

[1] http://post-office.corp.redhat.com/archives/rhos-tech/2018-March/msg00363.html

Comment 1 James Slagle 2018-03-29 13:36:19 UTC

this may be as simple as cron'ing our custom discover_hosts script or not documenting that NovaSchedulerDiscoverHostsInCellsInterval must be set for this use case to work.

Could also consider enabling NovaSchedulerDiscoverHostsInCellsInterval by default as currently it's disabled unless deploying Ironic in the overcloud.

Comment 3 Ollie Walsh 2018-10-31 11:36:58 UTC

*** Bug 1644418 has been marked as a duplicate of this bug. ***

Comment 10 Victor Voronkov 2019-04-22 13:57:00 UTC

verified on compose 2019-04-18.2

Comment 12 errata-xmlrpc 2019-04-30 17:27:35 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2019:0939