Resource Providers - Custom Resource Classes

https://blueprints.launchpad.net/nova/+spec/custom-resource-classes

We propose to provide the ability for an administrator to create a set of special resource classes that indicate deployer-specific resources that can be provided by a resource provider.

Problem description

Some hardware resources should be represented as a singular unit of consumable resource. These singular units of consumable resources may vary from one cloud offering to another, and attempting to create a standardized resource class identifier for these types of resources that can be used across different OpenStack clouds is simply not possible.

We require a method for cloud administrators to create new resource classes that represent consumable units of some resource.

Use Cases

As a cloud deployer providing baremetal resources to my users, I wish to utilize the new resource providers functionality for the Nova scheduler to place a request for different configurations of baremetal hardware to a provider of those resources. I also wish to use the new placement REST API to see a consistent view of the inventory and allocations of those resources to various users of my cloud.

As an NFV deployer, I have hardware that has some fully programmable gate array (FPGA) devices. These FPGAs may be flashed with a synthesized RT netlist containing an algorithm or entire software program that is accelerated. Each of these algorithms has one or more contexts that can be consumed by a guest virtual machine. I wish to allow my users to specify to launch an instance and have the instance consume one or more of the contexts for a particular algorithm that I have loaded onto the FPGAs on a compute node.

Proposed change

We propose the addition of a few things:

  • Changes and additions to nova.objects objects to handle custom resource classes. All custom resource classes will be prefixed with the string “CUSTOM_”.
  • New resource_classes database table storing the string -> integer mapping for custom resource classes
  • An additional placement REST API call for creating, modifying, deleting and querying custom resource classes

Alternatives

None.

Data model impact

A new lookup table for resource classes is introduced in the API database:

CREATE TABLE resource_classes (
    id INT NOT NULL,
    name VARCHAR(255) NOT NULL,
    PRIMARY KEY (id),
    UNIQUE INDEX (name)
);

The nova.objects.fields.ResourceClass is an Enum field that lists the standard known resource classes like VCPU, MEMORY_MB, DISK_GB, etc. We will need to make some modifications to this class and the object models that have a ResourceClass field (Allocation and Inventory object models). We will sort during the implementation phase the details about that, probably a StringField field type that could allow us not touching the object version anytime a new class is added.

This new ResourceClass object model would look up its integer index values in a new cache utility that would look for string values in the enumerated standard resource classes and, if not found, look up records in the new resource_classes table.

REST API impact

A set of new REST API commands will be created on the placement REST API with a new microversion:

  • GET /resource_classes: Returns list of all resource classes (standard as well as custom)
  • POST /resource_classes: Creates a new custom resource class
  • PUT /resource_classes/{name}: Change the string name of an existing custom resource class
  • DELETE /resource_classes/{name}: Removes a custom resource class

GET /resource_classes

Return a list of all resource classes defined for this Nova deployment. Pagination could be envisaged during the implementation phase if we consider that it could become a very long list, where the marker could be a resource class name and the list be alphabetically sorted by name.

Example:

200 OK
Content-Type: application/json
{
  "resource_classes": [
  {
    "name": "VCPU",
    "links": [
      {
        "rel": "self",
        "href": "/resource_classes/VCPU"
      }
    ]
  },
  {
    "name": "MEMORY_MB",
    "links": [
      {
        "rel": "self",
        "href": "/resource_classes/MEMORY_MB"
      }
    ]
  }
  ...
  {
    "name": "CUSTOM_BAREMETAL_GOLD",
    "links": [
      {
        "rel": "self",
        "href": "/resource_classes/CUSTOM_BAREMETAL_GOLD"
      }
    ]
  }
  ]
}

POST /resource_classes

Creates a new custom resource class.

Example:

POST /resource_classes
{
  "name": "CUSTOM_BAREMETAL_GOLD"
}

The body of the request must match the following JSONSchema document:

{
  "type": "object",
  "properties": {
    "name": {
      "type": "string",
      "pattern": "^CUSTOM\_[A-Z0-9_]*"
    },
},
  "required": [
    "name"
  ]
  "additionalProperties": False
}

The response body is empty. The headers include a location header pointing to the created resource class:

201 Created
Location: /resource_classes/CUSTOM_BAREMETAL_GOLD
  • A 400 Bad Request response code will be returned if name is for a standard resource class – i.e. VCPU or MEMORY_MB.
  • A 409 Conflict response code will be returned if another resource class exists with the provided name.

PUT /resource_classes/{name}

Changes the string name of an existing custom resource class.

Example:

PUT /resource_classes/CUSTOM_BAREMETAL_GOLD
{
  "name": "CUSTOM_BAREMETAL_SILVER"
}

The body of the request must match the following JSONSchema document:

{
  "type": "object",
  "properties": {
    "name": {
      "type": "string",
      "pattern": "^CUSTOM\_[A-Z0-9_]*"
    },
},
  "required": [
    "name"
  ]
  "additionalProperties": False
}

The response body will contain the resource class details and the response code will be a 200 OK upon successful name change.

Example:

200 OK
Content-Type: application/json
{
  "name": "CUSTOM_BAREMETAL_SILVER",
  "links": [
    {
      "rel": "self",
      "href": "/resource_classes/CUSTOM_BAREMETAL_SILVER"
    }
  ]
}
  • A 404 Not Found response code will be returned if no such resource class matching the name is found.
  • A 400 Bad Request response code will be returned if name is for a standard resource class – i.e. VCPU or MEMORY_MB.
  • A 409 Conflict response code will be returned if there is an existing resource class with the same name.

DELETE /resource_classes/{name}

Deletes an existing custom resource class.

Example:

DELETE /resource_classes/CUSTOM_BAREMETAL_GOLD

The response body is empty and the response code will be a 204 No Content upon successful deletion.

  • A 404 Not Found response code will be returned if no such resource class matching the name is found.
  • A 400 Bad Request response code will be returned if name is for a standard resource class – i.e. VCPU or MEMORY_MB.
  • A 409 Conflict response code will be returned if there are existing inventories or allocations for the resource class.

Security impact

None.

Notifications impact

None.

Other end user impact

None.

Performance Impact

None.

Other deployer impact

None.

Developer impact

None.

Implementation

Assignee(s)

Primary assignee:
jaypipes
Other contributors:
cdent edleafe bauzas

Work Items

  • Create new resource_classes lookup table in API database
  • Create nova/objects/resource_class.py object model, deprecating the old nova.objects.fields.ResourceClass classes
  • Add all new placement REST API commands

Dependencies

  • generic-resource-pools blueprint implemented

Testing

Unit and functional API tests using Gabbi.

Documentation Impact

API reference documentation needed.

References

None.