diff --git a/auditmiddleware/_api.py b/auditmiddleware/_api.py
index 1ea117e..b9fdf5f 100644
--- a/auditmiddleware/_api.py
+++ b/auditmiddleware/_api.py
@@ -57,8 +57,12 @@
 def _make_uuid(s):
     if s.isdigit():
         return str(uuid.UUID(int=int(s)))
-    else:
-        return s
+    # Extract the UUID from HATEOAS-style resource refs (e.g. secret_ref,
+    # container_ref) that carry a full URL instead of a bare UUID.
+    # pycadf's identifier.py warns when a non-UUID string is used as an id.
+    if '://' in s:
+        s = s.rstrip('/').rsplit('/', 1)[-1]
+    return s
 
 
 class ConfigError(Exception):
diff --git a/auditmiddleware/tests/unit/test_mappings.py b/auditmiddleware/tests/unit/test_mappings.py
index 00a200e..1a9f368 100644
--- a/auditmiddleware/tests/unit/test_mappings.py
+++ b/auditmiddleware/tests/unit/test_mappings.py
@@ -600,3 +600,106 @@ def test_get_list_zones(self):
         self.check_event(request, response, event, taxonomy.ACTION_LIST,
                          "service/dns/zones",
                          None, self.service_name)
+
+
+class BarbicanAuditMappingTest(base.BaseAuditMiddlewareTest):
+    """Test the barbican mapping file.
+
+    Barbican uses HATEOAS-style refs (full URLs) as ID fields in its
+    response bodies (e.g. ``secret_ref``, ``container_ref``). The
+    ``custom_id`` mapping points at these fields, so the middleware must
+    extract the bare UUID from the URL instead of forwarding the whole URL
+    as the CADF target ID — otherwise pycadf emits a UserWarning about
+    invalid UUIDs.
+    """
+
+    def setUp(self):
+        """Set up the Barbican audit mapping test."""
+        super(BarbicanAuditMappingTest, self).setUp()
+
+        self.audit_map_file_fixture = os.path.realpath(
+            "etc/barbican_audit_map.yaml")
+
+        self.service_name = 'barbican'
+        self.service_type = 'data/security/keymanager'
+
+    @property
+    def audit_map(self):
+        """The audit mapping filename under test."""
+        return self.audit_map_file_fixture
+
+    def test_post_create_secret_extracts_uuid_from_ref(self):
+        """UUID must be extracted from the HATEOAS secret_ref URL.
+
+        When a secret is created (POST /v1/secrets) barbican returns a
+        ``secret_ref`` containing a full URL such as:
+        ``https://keymanager.example.com:443/v1/secrets/<uuid>``
+
+        The ``custom_id: secret_ref`` mapping causes the middleware to read
+        this field as the resource ID.  Without the URL-stripping fix the
+        whole URL is passed to pycadf, which issues:
+
+            UserWarning: Invalid uuid: https://…/v1/secrets/<uuid>.
+            To ensure interoperability, identifiers should be a valid uuid.
+
+        After the fix only the trailing UUID segment must appear as the CADF
+        target id.
+        """
+        secret_id = str(uuid.uuid4())
+        secret_ref = 'https://keymanager-3.eu-de-1.cloud.sap:443/v1/secrets/' \
+                     + secret_id
+
+        url = '/v1/secrets'
+        req_json = {'name': 'my-secret', 'payload': 'secret-value'}
+        resp_json = {'secret_ref': secret_ref}
+
+        import warnings
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter('always')
+            request, response = self.build_api_call(
+                'POST', url, req_json=req_json, resp_json=resp_json)
+            event = self.build_event(request, response)
+            pycadf_warnings = [
+                w for w in caught
+                if 'Invalid uuid' in str(w.message)
+            ]
+
+        self.assertFalse(
+            pycadf_warnings,
+            "pycadf emitted 'Invalid uuid' warnings — the full URL was "
+            "forwarded as the CADF target id instead of the bare UUID: %s"
+            % [str(w.message) for w in pycadf_warnings])
+
+        self.check_event(request, response, event, taxonomy.ACTION_CREATE,
+                         "data/security/keymanager/secret", secret_id)
+
+    def test_post_create_container_extracts_uuid_from_ref(self):
+        """Same URL-stripping fix applies to container_ref."""
+        container_id = str(uuid.uuid4())
+        container_ref = \
+            'https://keymanager-3.eu-de-1.cloud.sap:443/v1/containers/' \
+            + container_id
+
+        url = '/v1/containers'
+        req_json = {'name': 'my-container', 'type': 'generic'}
+        resp_json = {'container_ref': container_ref}
+
+        import warnings
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter('always')
+            request, response = self.build_api_call(
+                'POST', url, req_json=req_json, resp_json=resp_json)
+            event = self.build_event(request, response)
+            pycadf_warnings = [
+                w for w in caught
+                if 'Invalid uuid' in str(w.message)
+            ]
+
+        self.assertFalse(
+            pycadf_warnings,
+            "pycadf emitted 'Invalid uuid' warnings — the full URL was "
+            "forwarded as the CADF target id instead of the bare UUID: %s"
+            % [str(w.message) for w in pycadf_warnings])
+
+        self.check_event(request, response, event, taxonomy.ACTION_CREATE,
+                         "data/security/keymanager/container", container_id)