mogan-specs/specs/pike/approved/node-aggregate.rst

Node Aggregates

https://blueprints.launchpad.net/mogan/+spec/node-aggregate

This introduces the concept of aggregate into Mogan, which is quite like Nova host aggregate, but we are based on baremetal nodes. Node aggregate allows the partition of baremetal nodes into logical groups for server distribution.

Problem description

Currently Mogan only have a concept of availability zones which is for providing isolation and redundancy from other availability zones. We need a mechanism to further partitioning baremetal nodes.

Use Cases

• As a cloud operator, I want to classify baremetal nodes based on the location like rack, row, cage, zone, DC.
• As a cloud operator, I want to classify baremetal nodes based on the hardware specs like with GPU, FPGA, ceph storage backend.

Proposed change

* A new mogan.objects.aggregate.Aggregate object would be added to the object model.

* Add a set of API that only allow admins to create, delete, and list aggregates, also admins should be able to add nodes to the specific aggregate and remove nodes from it.

* When do resources update we will cache the resource providers and the map of aggregates with resource providers. Add a node list API for admins which will derive resource providers from the cache.

* Before scheduling, mogan will handle the flavor resource_aggregates matching with node aggregate metadata, then got a list of aggregates, and pass it to placement with member_of parameter when listing resource providers:

/resource_providers?member_of=in:{agg1_uuid},{agg2_uuid},{agg3_uuid}

Alternatives

None

Data model impact

The proposed change will be adding the following fields to the aggregate object with their data type and default value for migrations.

Field Name	Field Type
id	Integer
uuid	UUID
name	String
metadata	DictOfStrings

For the database schema, the following table constructs would suffice :

op.create_table(
    'aggregates',
    sa.Column('created_at', sa.DateTime(), nullable=True),
    sa.Column('updated_at', sa.DateTime(), nullable=True),
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('uuid', sa.String(length=36), nullable=False),
    sa.Column('name', sa.String(length=255), nullable=False),
    sa.PrimaryKeyConstraint('id'),
    mysql_ENGINE='InnoDB',
    mysql_DEFAULT_CHARSET='UTF8'
)

op.create_table(
    'aggregate_metadata',
    sa.Column('created_at', sa.DateTime(), nullable=True),
    sa.Column('updated_at', sa.DateTime(), nullable=True),
    sa.Column('id', sa.Integer(), primary_key=True, nullable=False),
    sa.Column('key', sa.String(length=255), nullable=False),
    sa.Column('value', sa.String(length=255), nullable=False),
    sa.Column('aggregate_id', sa.Integer(), nullable=False),
    sa.PrimaryKeyConstraint('id'),
    sa.ForeignKeyConstraint(['aggregate_id'],
                            ['aggregate.id']),
    mysql_ENGINE='InnoDB',
    mysql_DEFAULT_CHARSET='UTF8'
)

REST API impact

• To create a new aggregate, a user will :

  POST /v1/aggregates

  With a body containing the JSON description of the aggregate.

  JSON Schema:

  {
      "type": "object",
      "properties": {
          "name": {"type": "string", "minLength": 1, "maxLength": 255},
          "metadata": {
              'type': 'object',
              'patternProperties': {
                  '^[a-zA-Z0-9-_:. ]{1,255}$': {
                      'type': 'string', 'maxLength': 255
                  }
              },
              'additionalProperties': False
          },
      },
      "required": ["name"],
      "additionalProperties": False,
  }

• To list aggregates, a user will :

  GET /v1/aggregates

• To show aggregate details, a user will :

  GET /v1/aggregates/{aggregate_id}

• To update aggregate, a user will :

  PATCH /v1/aggregates/{aggregate_id}

  With a body containing the JSON description of the fileds to be updated.

  Example Update Aggregate: JSON request:

  [

  {

  "op": "replace", "path": "/name", "value": "foo"

  }, { "op": "add", "path": "/metadata/k1", "value": "v1" }

  ]

• To delete an aggregate, a user will :

  DELETE /v1/aggregates/{aggregate_id}

• To add nodes to an aggregate, a user will :

  POST /v1/aggregates/{aggregate_id}/nodes

  With a body containing a list of node uuid to be added to the aggregate.

• To remove node from an aggregate, a user will :

  DELETE /v1/aggregates/{aggregate_id}/nodes/{node}

• To get nodes from an aggregate, a user will :

  GET /v1/aggregates/{aggregate_id}/nodes

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:

<niu-zglinux>

Work Items

• Add aggregate object.
• Add APIs that allows an admin to add, remove, and list node aggregates.
• Add APIs that allows an admin to add/remove nodes to an aggregate.
• Add new CLIs to manage node aggregates.

Dependencies

None

Testing

Unit Testing will be added.

Documentation Impact

Docs about node aggregates will be added.

References

None