Mechanism driver API: resource_provider_uuid5_namespace

A UUID v5 namespace for mechanism drivers wanting to report resource
providers to Placement.

Change-Id: I65ea084739b190b0553b63d0775baf0c27504ede
Needed-By: https://review.openstack.org/586597
Partial-Bug: #1578989
Related-Change: https://review.openstack.org/574781
See-Also: https://review.openstack.org/502306 (nova spec)
See-Also: https://review.openstack.org/508149 (neutron spec)

neutron_lib/plugins/ml2/api.py

@@ -55,6 +55,19 @@ class MechanismDriver(object):
     methods that are part of the database transaction.
     """
 
+    # Used in generating resource provider UUIDs for physical network
+    # interfaces. Each mechanism driver supporting Placement should have its
+    # own UUID v5 namespace (which is a UUID v1 in turn). When set to a
+    # concrete value use a uuid.UUID() object, not the string format.
+    # It will be used when hashing RP UUIDs from:
+    #     (mech driver namespace, hostname, physical bridge/interface name)
+    # When needed generate new namespace UUIDs by:
+    #     python -c 'import uuid ; print uuid.uuid1()'
+    # See also:
+    #     https://tools.ietf.org/html/rfc4122
+    #     https://stackoverflow.com/a/7816117
+    resource_provider_uuid5_namespace = None
+
     @abc.abstractmethod
     def initialize(self):
         """Perform driver initialization.

releasenotes/notes/resource-provider-uuid5-namespace-f7276ba1945ce82f.yaml

@@ -0,0 +1,13 @@
+---
+features:
+  - |
+    New MechanismDriver API class property:
+    ``resource_provider_uuid5_namespace``.  Mechanism drivers wanting
+    to support resource provider information reporting to Placement
+    (eg. reporting resource providers to guarantee some minimum bandwidth
+    allocated on them later) must set this class property to a UUID
+    object unique to that mechanism driver. It will be used as a UUID
+    v5 namespace in generating UUIDs for resource providers. The default
+    implementation sets it to ``None``, meaning that the mechanism driver
+    does not support resource provider information reporting to Placement.
+    Unaffected drivers need not be changed.