openstack/specs/quota-custom-resource-class.rst

https://blueprints.launchpad.net/nova/+spec/tbd

With this blueprint we introduce a way to define and use quotas per custom resources classes, so that operator can limit how DC resources are utilized.

Problem description

Currently, quotas in Nova are restricted only for selected resources like CPU cores, ram, floating IPs, and for non-resource things: number of instances, metadata items, key pairs, server groups and so on. Introducing custom resource classes within placement service, allows operator to create resources, which are unknown to the quota mechanism.

Use Cases

As an operator I’d like to define quota for custom resource classes, so that amount of such resources can be limited per project and/or per user.

Proposed change

We propose to add ability for dynamically adding custom resource classes to resources which QuotaEngine can handle, and track the usage like all the other resources.

Alternatives

As an alternative, we could leverage Quota Classes to be used instead of affecting QuotaEngine, although it will require slightly more effort in implementation, since there is no tracking of resources within that model, and, what's more important, quota classes are used for setting/changing defaults which comes from configuration.

We could also make a custom scheduler filter, which would count the resources usage and limits for anything operator needs, however this will have performance impact, since originally limits are checked during API call, and scheduler filters are executed on scheduling phase.

Data model impact

New attribute uuid will be added to the Quotas object.

REST API impact

New API methods will be introduced to list/add/delete/modify to the os-quota-sets for a project and optionally user.

Optionally, GET /os-quota-sets/{tenant_id} will provide a list of custom resources in under quota_set["custom_resources"] key in JSON response.

• Getting the list of defined custom resources in limits:

  GET /os-quota-sets/{tenant_id}/custom_resource
  
  200 OK
  Content-Type: application/json
  
  {
      "custom_resources": [
          {
              "name": "name of custom resource class",
              "UUID": "uuid of custom resource class from resource provider",
              "limit": 0
          },
           ...
      ]
  }

• Getting a definition of the particular custom resources in limits:

  GET /os-quota-sets/{tenant_id}/custom_resource/{resource_uuid}
  
  200 OK
  Content-Type: application/json
  
  {
      "name": "name of custom resource class",
      "UUID": "uuid of custom resource class from resource provider",
      "limit": 0
  }

• Adding custom resource to quotas:

  POST /os-quota-sets/{tenant_id}/custom_resource

  with a payload:

  Content-Type: application/json
  
  {
      "name": "name of custom resource class",
      "UUID": "uuid of custom resource class from resource provider",
      "limit": 0
  }

  Response body is empty. Response code will be 201 Created on success, or 409 Conflict if there is resource with such UUID already created.

  • 200 OK on success.

  • 400 Bad Request for bad or invalid syntax.

  • 409 Conflict if there is resource with such UUID already created.

• Updating limit value for the custom resource:

  PUT /os-quota-sets/{tenant_id}/custom_resource/{resource_uuid}

  with a payload:

  Content-Type: application/json
  
  {
      "limit": 10
  }

  Response body is empty. Response code will be:

  • 200 OK on success.

  • 400 Bad Request for bad or invalid syntax.

  • 404 Not Found on undefined custom resource.

• Removing the custom resource from limits:

  DELETE /os-quota-sets/{tenant_id}/custom_resource/{resource_uuid}

  Request body is empty. Response body is empty. Response code will be:

  • 200 OK on success.

  • 404 Not Found on undefined custom resource.

Security impact

None

Notifications impact

None

Other end user impact

Nova-client and/or openstack client should be updated to be able to provide custom resource class as an argument for quota* subcommands.

Performance Impact

None

Other deployer impact

None

Developer impact

None

Upgrade impact

None

Implementation

Assignee(s)

Primary assignee:

<launchpad-id or None>

Other contributors:

<launchpad-id or None>

Work Items

• DB changes

• Hook to register custom resource class in QuotaEngine._resources dict

• API implementation

Dependencies

None

Testing

Unit test have to be provided.

Documentation Impact

Documentation of additional API calls have to be updated.

References

None

History

Revisions

Release Name	Description
Rocky	Introduced