diff --git a/nova/api/openstack/placement/handlers/allocation_candidate.py b/nova/api/openstack/placement/handlers/allocation_candidate.py
index cc3eaae28..5d30ffd95 100644
--- a/nova/api/openstack/placement/handlers/allocation_candidate.py
+++ b/nova/api/openstack/placement/handlers/allocation_candidate.py
@@ -18,6 +18,7 @@ from oslo_log import log as logging
 from oslo_serialization import jsonutils
 from oslo_utils import encodeutils
 from oslo_utils import timeutils
+import six
 import webob
 
 from nova.api.openstack.placement import microversion
@@ -117,9 +118,10 @@ def _transform_allocation_requests_list(alloc_reqs):
     return results
 
 
-def _transform_provider_summaries(p_sums):
+def _transform_provider_summaries(p_sums, include_traits=False):
     """Turn supplied list of ProviderSummary objects into a dict, keyed by
-    resource provider UUID, of dicts of provider and inventory information.
+    resource provider UUID, of dicts of provider and inventory information. The
+    traits only show up when `include_traits` is `True`.
 
     {
        RP_UUID_1: {
@@ -132,7 +134,11 @@ def _transform_provider_summaries(p_sums):
                 'capacity': 4,
                 'used': 0,
               }
-           }
+           },
+           'traits': [
+                'HW_CPU_X86_AVX512F',
+                'HW_CPU_X86_AVX512CD'
+           ]
        },
        RP_UUID_2: {
            'resources': {
@@ -144,20 +150,32 @@ def _transform_provider_summaries(p_sums):
                 'capacity': 4,
                 'used': 0,
               }
-           }
+           },
+           'traits': [
+                'HW_NIC_OFFLOAD_TSO',
+                'HW_NIC_OFFLOAD_GRO'
+           ]
        }
     }
     """
-    return {
-        ps.resource_provider.uuid: {
-            'resources': {
-                psr.resource_class: {
-                    'capacity': psr.capacity,
-                    'used': psr.used,
-                } for psr in ps.resources
-            }
-        } for ps in p_sums
-    }
+
+    ret = {}
+
+    for ps in p_sums:
+        resources = {
+            psr.resource_class: {
+                'capacity': psr.capacity,
+                'used': psr.used,
+            } for psr in ps.resources
+        }
+
+        ret[ps.resource_provider.uuid] = {'resources': resources}
+
+        if include_traits:
+            ret[ps.resource_provider.uuid]['traits'] = [
+                t.name for t in ps.traits]
+
+    return ret
 
 
 def _transform_allocation_candidates(alloc_cands, want_version):
@@ -175,7 +193,10 @@ def _transform_allocation_candidates(alloc_cands, want_version):
     else:
         a_reqs = _transform_allocation_requests_list(
             alloc_cands.allocation_requests)
-    p_sums = _transform_provider_summaries(alloc_cands.provider_summaries)
+
+    include_traits = want_version.matches((1, 17))
+    p_sums = _transform_provider_summaries(alloc_cands.provider_summaries,
+                                           include_traits)
     return {
         'allocation_requests': a_reqs,
         'provider_summaries': p_sums,
@@ -195,7 +216,9 @@ def list_allocation_candidates(req):
     context = req.environ['placement.context']
     want_version = req.environ[microversion.MICROVERSION_ENVIRON]
     get_schema = schema.GET_SCHEMA_1_10
-    if want_version.matches((1, 16)):
+    if want_version.matches((1, 17)):
+        get_schema = schema.GET_SCHEMA_1_17
+    elif want_version.matches((1, 16)):
         get_schema = schema.GET_SCHEMA_1_16
     util.validate_query_params(req, get_schema)
 
@@ -213,6 +236,8 @@ def list_allocation_candidates(req):
         raise webob.exc.HTTPBadRequest(
             _('Invalid resource class in resources parameter: %(error)s') %
             {'error': exc})
+    except exception.TraitNotFound as exc:
+        raise webob.exc.HTTPBadRequest(six.text_type(exc))
 
     response = req.response
     trx_cands = _transform_allocation_candidates(cands, want_version)
diff --git a/nova/api/openstack/placement/microversion.py b/nova/api/openstack/placement/microversion.py
index 637ac1a3d..19ac3c462 100644
--- a/nova/api/openstack/placement/microversion.py
+++ b/nova/api/openstack/placement/microversion.py
@@ -58,6 +58,8 @@ VERSIONS = [
              # representation and 'in_tree' filter on GET /resource_providers
     '1.15',  # Include last-modified and cache-control headers
     '1.16',  # Add 'limit' query parameter to GET /allocation_candidates
+    '1.17',  # Add 'required' query parameter to GET /allocation_candidates and
+             # return traits in the provider summary.
 ]
 
 
diff --git a/nova/api/openstack/placement/rest_api_version_history.rst b/nova/api/openstack/placement/rest_api_version_history.rst
index 7e7c27ebd..c88e241a4 100644
--- a/nova/api/openstack/placement/rest_api_version_history.rst
+++ b/nova/api/openstack/placement/rest_api_version_history.rst
@@ -214,3 +214,10 @@ header has been added to prevent inadvertent caching of resources.
 Add support for a ``limit`` query parameter when making a
 ``GET /allocation_candidates`` request. The parameter accepts an integer
 value, `N`, which limits the maximum number of candidates returned.
+
+1.17 Add 'required' parameter to the allocation candidates
+----------------------------------------------------------
+
+Add the `required` parameter to the `GET /allocation_candidates` API. It
+accepts a list of traits separated by `,`. The provider summary in the response
+will include the attached traits also.
diff --git a/nova/api/openstack/placement/schemas/allocation_candidate.py b/nova/api/openstack/placement/schemas/allocation_candidate.py
index d155f8ef0..ff7216074 100644
--- a/nova/api/openstack/placement/schemas/allocation_candidate.py
+++ b/nova/api/openstack/placement/schemas/allocation_candidate.py
@@ -40,3 +40,9 @@ GET_SCHEMA_1_16['properties']['limit'] = {
     "minimum": 1,
     "minLength": 1
 }
+
+# Add required parameter.
+GET_SCHEMA_1_17 = copy.deepcopy(GET_SCHEMA_1_16)
+GET_SCHEMA_1_17['properties']['required'] = {
+    "type": ["string"]
+}
diff --git a/nova/api/openstack/placement/util.py b/nova/api/openstack/placement/util.py
index 552ba2200..30961cd10 100644
--- a/nova/api/openstack/placement/util.py
+++ b/nova/api/openstack/placement/util.py
@@ -306,8 +306,8 @@ def normalize_traits_qs_param(val):
     """
     ret = set(substr.strip() for substr in val.split(','))
     if not all(trait for trait in ret):
-        msg = _('Malformed traits parameter. Expected query string value '
-                'of the form: HW_CPU_X86_VMX,CUSTOM_MAGIC. '
+        msg = _('Invalid query string parameters: Expected \'required\' '
+                'parameter value of the form: HW_CPU_X86_VMX,CUSTOM_MAGIC. '
                 'Got: "%s"') % val
         raise webob.exc.HTTPBadRequest(msg)
     return ret
diff --git a/nova/tests/functional/api/openstack/placement/fixtures.py b/nova/tests/functional/api/openstack/placement/fixtures.py
index 9e9634678..549643c5d 100644
--- a/nova/tests/functional/api/openstack/placement/fixtures.py
+++ b/nova/tests/functional/api/openstack/placement/fixtures.py
@@ -271,6 +271,10 @@ class SharedStorageFixture(APIFixture):
             inv_list = rp_obj.InventoryList(objects=[vcpu_inv, ram_inv])
             cn.set_inventory(inv_list)
 
+        t_avx_sse = rp_obj.Trait.get_by_name(self.context, "HW_CPU_X86_SSE")
+        t_avx_sse2 = rp_obj.Trait.get_by_name(self.context, "HW_CPU_X86_SSE2")
+        cn1.set_traits(rp_obj.TraitList(objects=[t_avx_sse, t_avx_sse2]))
+
         # Populate shared storage provider with DISK_GB inventory
         disk_inv = rp_obj.Inventory(
             self.context,
diff --git a/nova/tests/functional/api/openstack/placement/gabbits/allocation-candidates.yaml b/nova/tests/functional/api/openstack/placement/gabbits/allocation-candidates.yaml
index 36cfa1053..6b94e0f5c 100644
--- a/nova/tests/functional/api/openstack/placement/gabbits/allocation-candidates.yaml
+++ b/nova/tests/functional/api/openstack/placement/gabbits/allocation-candidates.yaml
@@ -170,3 +170,80 @@ tests:
       openstack-api-version: placement 1.16
   response_json_paths:
       $.allocation_requests.`len`: 1
+
+- name: get allocation candidates with required traits in old version
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=HW_CPU_X86_SSE
+  status: 400
+  request_headers:
+      openstack-api-version: placement 1.16
+  response_strings:
+      - Invalid query string parameters
+      - "'required' was unexpected"
+
+- name: get allocation candidates without traits summary in old version
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100
+  status: 200
+  request_headers:
+      openstack-api-version: placement 1.16
+  response_json_paths:
+       $.provider_summaries["$ENVIRON['CN1_UUID']"].`len`: 1
+       $.provider_summaries["$ENVIRON['CN2_UUID']"].`len`: 1
+
+- name: get allocation candidates with invalid trait
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=INVALID_TRAIT
+  status: 400
+  request_headers:
+      openstack-api-version: placement 1.17
+  response_strings:
+      - No such trait(s)
+
+- name: get allocation candidates with empty required value
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=
+  status: 400
+  request_headers:
+      openstack-api-version: placement 1.17
+  response_strings:
+      - "Invalid query string parameters: Expected 'required' parameter value of the form: HW_CPU_X86_VMX,CUSTOM_MAGIC."
+
+- name: get allocation candidates with invalid required value
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=,,
+  status: 400
+  request_headers:
+      openstack-api-version: placement 1.17
+  response_strings:
+      - "Invalid query string parameters: Expected 'required' parameter value of the form: HW_CPU_X86_VMX,CUSTOM_MAGIC."
+
+- name: get allocation candidates with required trait
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=HW_CPU_X86_SSE
+  status: 200
+  request_headers:
+      openstack-api-version: placement 1.17
+  response_json_paths:
+      $.allocation_requests.`len`: 1
+      $.provider_summaries.`len`: 2
+      $.provider_summaries["$ENVIRON['CN1_UUID']"].`len`: 2
+      $.provider_summaries["$ENVIRON['CN1_UUID']"].traits.`sorted`:
+          - HW_CPU_X86_SSE
+          - HW_CPU_X86_SSE2
+
+- name: get allocation candidates with multiple required traits
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=HW_CPU_X86_SSE,HW_CPU_X86_SSE2
+  status: 200
+  request_headers:
+      openstack-api-version: placement 1.17
+  response_json_paths:
+      $.allocation_requests.`len`: 1
+      $.provider_summaries.`len`: 2
+      $.provider_summaries["$ENVIRON['CN1_UUID']"].`len`: 2
+      $.provider_summaries["$ENVIRON['CN1_UUID']"].traits.`sorted`:
+          - HW_CPU_X86_SSE
+          - HW_CPU_X86_SSE2
+
+- name: get allocation candidates with required trait and no matching
+  GET: /allocation_candidates?resources=VCPU:1,MEMORY_MB:1024,DISK_GB:100&required=HW_CPU_X86_SSE3
+  status: 200
+  request_headers:
+      openstack-api-version: placement 1.17
+  response_json_paths:
+      $.allocation_requests.`len`: 0
+      $.provider_summaries.`len`: 0
diff --git a/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml b/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml
index e4f098a6c..2a40d4f5c 100644
--- a/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml
+++ b/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml
@@ -39,13 +39,13 @@ tests:
   response_json_paths:
       $.errors[0].title: Not Acceptable
 
-- name: latest microversion is 1.16
+- name: latest microversion is 1.17
   GET: /
   request_headers:
       openstack-api-version: placement latest
   response_headers:
       vary: /OpenStack-API-Version/
-      openstack-api-version: placement 1.16
+      openstack-api-version: placement 1.17
 
 - name: other accept header bad version
   GET: /
diff --git a/placement-api-ref/source/allocation_candidates.inc b/placement-api-ref/source/allocation_candidates.inc
index 9ed805e62..cccd4391c 100644
--- a/placement-api-ref/source/allocation_candidates.inc
+++ b/placement-api-ref/source/allocation_candidates.inc
@@ -31,6 +31,7 @@ Request
 
   - resources: resources_query_required
   - limit: allocation_candidates_limit
+  - required: allocation_candidates_required
 
 Response (microversions 1.12 - )
 --------------------------------
diff --git a/placement-api-ref/source/parameters.yaml b/placement-api-ref/source/parameters.yaml
index e4d57e701..80e35417d 100644
--- a/placement-api-ref/source/parameters.yaml
+++ b/placement-api-ref/source/parameters.yaml
@@ -50,6 +50,16 @@ allocation_candidates_limit:
   description: >
     A positive integer used to limit the maximum number of allocation
     candidates returned in the response.
+allocation_candidates_required:
+  type: string
+  in: query
+  required: false
+  min_version: 1.17
+  description: >
+    Accepts a list of traits separated by `,`. Allocation requests in the
+    response will be for resource providers that have capacity for all
+    requested resources and the set of those resource providers will
+    *collectively* contain all of the required traits.
 member_of:
   type: string
   in: query
@@ -241,7 +251,8 @@ provider_summaries:
   required: true
   description: >
     A dictionary keyed by resource provider UUID,
-    of dictionaries of inventory/capacity information.
+    of dictionaries of inventory/capacity information. The list of traits
+    the resource provider has associated with it is included in version `1.17`.
 reserved: &reserved
   type: integer
   in: body
diff --git a/releasenotes/notes/allocation-candidates-traits-1adf079ed0c6563c.yaml b/releasenotes/notes/allocation-candidates-traits-1adf079ed0c6563c.yaml
new file mode 100644
index 000000000..af7aae46a
--- /dev/null
+++ b/releasenotes/notes/allocation-candidates-traits-1adf079ed0c6563c.yaml
@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Add ``required`` query parameter to the ``GET /allocation_candidates`` API
+    in new placement microversion 1.17. The parameter accepts a list of traits
+    separated by ``,``, which is used to further limit the list of allocation
+    requests to resource providers that have the capacity to fulfill the
+    requested resources AND *collectively* have all of the required traits
+    associated with them. In the same microversion, the candidate attached
+    traits returned in the provider summary.