Bug 1561010 – vdsm: perform only minimal changes to the domain XML received from Engine

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Bug 1561010 - vdsm: perform only minimal changes to the domain XML received from Engine

Summary:	vdsm: perform only minimal changes to the domain XML received from Engine

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Virtualization Manager
Classification:	Red Hat
Component:	vdsm (Show other bugs)
Sub Component:
Version:	4.2.3
Hardware:	Unspecified Unspecified

Priority	high Severity high
Target Milestone:	ovirt-4.2.3
Target Release:	---
Assigned To:	Francesco Romani
QA Contact:	Liran Rotenberg
Docs Contact:

URL:
Whiteboard:
Keywords:

Depends On:
Blocks:
	Show dependency tree / graph

Reported:	2018-03-27 08:42 EDT by Francesco Romani
Modified:	2018-05-15 13:54 EDT (History)
CC List:	7 users (show)

See Also:
Fixed In Version:
Doc Type:	If docs needed, set a value
Doc Text:
Story Points:	---
Clone Of:
Environment:
Last Closed:	2018-05-15 13:54:11 EDT
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	Virt
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
oVirt gerrit	89498	ovirt-4.2	MERGED	virt: introduce the domxml_preprocess module	2018-04-03 05:03 EDT
oVirt gerrit	89499	ovirt-4.2	MERGED	virt: domxml_preprocess: move fixers in the module	2018-04-03 05:03 EDT
oVirt gerrit	89500	ovirt-4.2	MERGED	virt: domxml_preprocess: make devices if missing	2018-04-03 05:03 EDT
oVirt gerrit	89501	ovirt-4.2	MERGED	tests: domxml_preprocess: kickstart tests	2018-04-03 05:04 EDT
oVirt gerrit	89502	ovirt-4.2	MERGED	tests: domxml_preprocess: test passthrough	2018-04-03 05:04 EDT
oVirt gerrit	89503	ovirt-4.2	MERGED	virt: lease: split parse_xml	2018-04-03 05:04 EDT
oVirt gerrit	89504	ovirt-4.2	MERGED	virt: lease: make helper public	2018-04-03 05:04 EDT
oVirt gerrit	89505	ovirt-4.2	MERGED	vm: don't replace device XML, only hooks output	2018-04-05 10:08 EDT
oVirt gerrit	89506	ovirt-4.2	MERGED	virt: extract local adjustments to XML	2018-04-05 10:09 EDT
oVirt gerrit	89507	ovirt-4.2	MERGED	virt: introduce the lookup module	2018-04-05 04:17 EDT
oVirt gerrit	89508	ovirt-4.2	MERGED	virt: storage: minimal changes to the drive XML	2018-04-05 10:13 EDT
oVirt gerrit	89509	ovirt-4.2	MERGED	virt: lease: minimal changes to the lease XML	2018-04-05 10:59 EDT
oVirt gerrit	89510	ovirt-4.2	MERGED	virt: placeholders: minimize replace_placeholders	2018-04-05 11:00 EDT
oVirt gerrit	89531	ovirt-4.2	MERGED	virt: devices: lookup: extract drive_by_serial	2018-04-05 11:00 EDT
oVirt gerrit	89532	ovirt-4.2	MERGED	virt: devices: log changes to disk devices	2018-04-06 03:11 EDT
oVirt gerrit	89533	ovirt-4.2	MERGED	virt: devices: log changes to lease devices	2018-04-06 03:11 EDT
oVirt gerrit	89582	master	ABANDONED	doxml_preprocess: I/O mode depends on disk type	2018-04-04 09:10 EDT
oVirt gerrit	89583	master	MERGED	tests: domxml_preprocess: add more monkeypatch	2018-03-29 06:22 EDT
oVirt gerrit	89594	master	MERGED	API: improve logging	2018-03-31 13:55 EDT
oVirt gerrit	89604	master	MERGED	domxml_preprocess: cdrom attr may be missing	2018-03-31 13:55 EDT
oVirt gerrit	89739	ovirt-4.2	MERGED	API: improve logging	2018-04-06 03:11 EDT
oVirt gerrit	89740	ovirt-4.2	MERGED	domxml_preprocess: cdrom attr may be missing	2018-04-06 03:12 EDT
oVirt gerrit	89879	ovirt-4.2	MERGED	tests: domxml_preprocess: add more monkeypatch	2018-04-06 04:18 EDT
Red Hat Product Errata	RHEA-2018:1489	None	None	None	2018-05-15 13:54 EDT

Groups: None (edit)

Description Francesco Romani 2018-03-27 08:42:50 EDT

Description of problem:
Vdsm currently replaces whole sections of XML to perform host-specific changes.
This means we override data from Engine, but Engine is the ultimate source of truth.

Vdsm should minimize those changes.
For hooks, there is no real choice but replace the XML snippet the hooks returned, so this still needs to be done.

For device-specific changes (e.g. NICs, drives, leases), Vdsm should strive to minimize the changes, modifying only the attributes (e.g. drive path, lease offsets) and not replacing the whole XML.

This will make much, much simpler to add features in Engine.

This is the tracker bug

Comment 1 Francesco Romani 2018-04-03 04:52:29 EDT

this change is completely transparent for the users -everything should work as before, or even better, thus doesn't require doc_text

Comment 3 Liran Rotenberg 2018-05-06 05:38:24 EDT

Verified on:
ovirt-engine-4.2.3.3-0.1.el7.noarch
vdsm-4.20.27-1.el7ev.x86_64
libvirt-3.9.0-14.el7_5.3.x86_64

Steps of verification:
Most of the normal flows are checked within the automation.

Some infrequent combinations that were tested manually:
1. hot-plug disk, create snapshot of it
steps:
a. create a VM.
b. start the VM.
c. hot-plug disk.
d. create snapshot of the VM.

2. hot-unplug disk, migrate the VM
steps:
a. create a VM.
b. start the VM.
c. hot-unplug disk.
d. migrate the VM.

3. hot-plug NIC, suspend VM, resume VM
steps:
a. create a VM.
b. start the VM.
c. hot-plug NIC.
d. suspend the VM.
e. resume the VM.

Comment 6 errata-xmlrpc 2018-05-15 13:54:11 EDT

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/RHEA-2018:1489

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