openstack/neutron
Code Issues Proposed changes
a212e07102
neutron/doc/source/contributor/internals/api_extensions.rst
Kailun Qin 563a536d02 Support Network Segment Range CRUD as extensions 
This patch adds the support for network segment range CRUD. Subsequent
patches will be added to use this network segment range on segment
allocation if this extension is loaded.

Changes include:
- an API extension which exposes the segment range to be administered;
- standard attributes with tagging support for the new resource;
- a new service plugin "network_segment_range" for the feature
  enabling/disabling;
- a new network segment range DB table model along with operation
  logic;
- Oslo Versioned Objects for network segment range data model;
- policy-in-code support for network segment range.

Co-authored-by: Allain Legacy <Allain.legacy@windriver.com>

Partially-implements: blueprint network-segment-range-management
Change-Id: I75814e50b2c9402fe6776229d469745d7a72290b
2019-03-07 08:20:30 +00:00

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API Extensions

API extensions is the standard way of introducing new functionality to the Neutron project, it allows plugins to determine if they wish to support the functionality or not.

Examples

The easiest way to demonstrate how an API extension is written, is by studying an existing API extension and explaining the different layers.

security_group_api

Extensions for Resources with standard attributes

Resources that inherit from the HasStandardAttributes DB class can automatically have the extensions written for standard attributes (e.g. timestamps, revision number, etc) extend their resources by defining the 'api_collections' on their model. These are used by extensions for standard attr resources to generate the extended resources map.

Any new addition of a resource to the standard attributes collection must be accompanied with a new extension to ensure that it is discoverable via the API. If it's a completely new resource, the extension describing that resource will suffice. If it's an existing resource that was released in a previous cycle having the standard attributes added for the first time, then a dummy extension needs to be added indicating that the resource now has standard attributes. This ensures that an API caller can always discover if an attribute will be available.

For example, if Flavors were migrated to include standard attributes, we need a new 'flavor-standardattr' extension. Then as an API caller, I will know that flavors will have timestamps by checking for 'flavor-standardattr' and 'timestamps'.

Current API resources extended by standard attr extensions:

  • subnets: neutron.db.models_v2.Subnet
  • trunks: neutron.services.trunk.models.Trunk
  • routers: neutron.db.l3_db.Router
  • segments: neutron.db.segments_db.NetworkSegment
  • security_group_rules: neutron.db.models.securitygroup.SecurityGroupRule
  • networks: neutron.db.models_v2.Network
  • policies: neutron.db.qos.models.QosPolicy
  • subnetpools: neutron.db.models_v2.SubnetPool
  • ports: neutron.db.models_v2.Port
  • security_groups: neutron.db.models.securitygroup.SecurityGroup
  • floatingips: neutron.db.l3_db.FloatingIP
  • network_segment_ranges: neutron.db.models.network_segment_range.NetworkSegmentRange