Return Selection Objects

Registered by Ed Leafe on 2017-08-29

This blueprint has been superseded. See the newer blueprint "Return Alternate Hosts" for updated plans.

Before Queens, the scheduler's select_destinations() method returned a dictionary representing the selected host for each requested instance. In Queens, however, this will change to return a list of these dictionaries for each instance, with the first item being the selected host, and the rest being optional hosts in case the initial build fails. What's more, each of these host dictionaries must also include the corresponding allocation dictionary that would be used to claim or unclaim the resources on that host for the instance. We propose to create a new Selection object that would contain these data structures, make accessing their elements simpler and clearer, and document what each field in the object represents.

Blueprint information

Status:
Complete
Approver:
None
Priority:
Undefined
Drafter:
Ed Leafe
Direction:
Needs approval
Assignee:
Ed Leafe
Definition:
Superseded
Series goal:
None
Implementation:
Implemented
Milestone target:
None
Started by
Matt Riedemann on 2018-02-08
Completed by
Matt Riedemann on 2017-10-03

Related branches

Sprints

Whiteboard

Addressed by: https://review.openstack.org/486215
    Add alternate hosts

Addressed by: https://review.openstack.org/499239
    WIP - Add ${Destination} and ${Destination}List objects

Gerrit topic: https://review.openstack.org/#q,topic:bp/return-selection-objects,n,z

Addressed by: https://review.openstack.org/498830
    Return Selection Objects

Addressed by: https://review.openstack.org/507245
    Set the Pike release version for scheduler RPC

Gerrit topic: https://review.openstack.org/#q,topic:bp/placement-allocation-requests,n,z

Does this need to be separate from https://blueprints.launchpad.net/nova/+spec/return-alternate-hosts ? Aren't they means to the same end? -- mriedem 20171003

(11:31:16 AM) edleafe: it's just the result of switching direction in the middle. Moving forward, let's put all the code under the return-alternate-hosts bp

Given that ^ I'm going to mark this bp as superseded by the return-alternate-hosts bp.

Addressed by: https://review.openstack.org/495854
    Return Selection objects from the scheduler driver

Gerrit topic: https://review.openstack.org/#q,topic:bp/return-alternate-hosts,n,z

(?)

Work Items

Dependency tree

* Blueprints in grey have been implemented.

This blueprint contains Public information 
Everyone can see this information.

Subscribers

No subscribers.