Bug 1309407

Summary:	[RFE] Add new API method to support processing updates to hypervisor-guest mappings using diffs only
Product:	[Community] Candlepin	Reporter:	Chris Snyder <csnyder>
Component:	candlepin	Assignee:	candlepin-bugs
Status:	CLOSED WONTFIX	QA Contact:	Katello QA List <katello-qa-list>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	2.0	CC:	bcourt, redakkan, wharris
Target Milestone:	---	Keywords:	FutureFeature
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Enhancement
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-07-17 14:09:06 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:	1239187

Description Chris Snyder 2016-02-17 17:35:25 UTC

* What *
A new API method for Candlepin that allows submission of updates to host guest mappings in the form of "diffs". These diffs would include any changes in a particular report annotated with whether the data was added, removed, or changed. (Much like the sorts of diffs that git generates).

Presently there is no API method to do this.

* Why *
This allows us to send much smaller sets of changes from virt-who and should allow us to process the changes more quickly. Most importantly this will allow us to scale the virt-who processing bits independently of the rest of candlepin. (Add more worker threads processing diffs that are coming off the queue).

This also opens up the option of other tools providing us with this information (as the other tools can submit just their changes)


* How *
While it is entirely up to the person(s) who implement it I have a few suggestions (based on my discussions with bcourt and alikins).

The method should accept a diff and place the diff in a durable queue (ensuring that the diffs are applied in order). To support diffs coming from multiple virt-who instances about the same server, a timestamp from the server must be included and used to accept or reject the request.

Comment 1 Barnaby Court 2016-05-13 17:13:02 UTC

As part of differentiating reports from multiple virt-who servers Candlepin will have to choose a primary server that is currently being listened to and if another server checks in, the reports will have to be ignored until some timeout occurs and then Candlepin will select a new primary to listen to. 

When a new primary is selected Candlepin will respond to the first diff report from the new primary with a request for a full report. After a full report from the new primary has been processed differential updating will continue from the new primary.

Comment 2 Rehana 2020-07-17 14:09:06 UTC

Closing the request based on the triage meeting .