Exceptions for: Drive binding by placement allocation

New exception types used in https://review.openstack.org/574783.

Change-Id: I46d89ef6d7630ec2c44d619c022aa8bbb6e51b63
Needed-By: https://review.openstack.org/574783
Partial-Bug: #1578989
See-Also: https://review.openstack.org/502306 (nova spec)
See-Also: https://review.openstack.org/508149 (neutron spec)

neutron_lib/exceptions/placement.py

@@ -69,3 +69,14 @@ class PlacementResourceProviderNameNotUnique(exceptions.Conflict):
 
 class PlacementClientError(exceptions.NeutronException):
     message = _("Placement Client Error (4xx): %(msg)s")
+
+
+class UnknownResourceProvider(exceptions.BadRequest):
+    """Resource provider not known by neutron backends."""
+    message = _("No such resource provider known by Neutron: %(rsc_provider)s")
+
+
+class AmbiguousResponsibilityForResourceProvider(exceptions.NeutronException):
+    """Not clear who's responsible for resource provider."""
+    message = _("Expected one driver to be responsible for resource provider "
+                "%(rsc_provider)s, but got many: %(drivers)s")

releasenotes/notes/placement-binding-exceptions-6362d52391b7023e.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    New exception classes: ``UnknownResourceProvider`` and
+    ``AmbiguousResponsibilityForResourceProvider``.