ntkathole · Jul 23, 2026 · Jul 22, 2026 · Jul 22, 2026 · Jul 22, 2026 · Jul 22, 2026
@@ -44,10 +44,11 @@ The server, in turn, uses the same OIDC server to validate the token and extract
 
 Some assumptions are made in the OIDC server configuration:
 * The OIDC token refers to a client with roles matching the RBAC roles of the configured `Permission`s (*)
-* The roles are exposed in the access token under `resource_access.<client_id>.roles`
+* The roles are exposed in the access token under `resource_access.<client_id>.roles` (Keycloak) or in the top-level `roles` claim (Entra ID app roles). Roles found in both are merged.
 * The JWT token is expected to have a verified signature and not be expired. The Feast OIDC token parser logic validates for `verify_signature` and `verify_exp` so make sure that the given OIDC provider is configured to meet these requirements.
-* The `preferred_username` should be part of the JWT token claim.
+* The username is read from the first of `preferred_username`, `upn`, `azp`, `appid`, `sub` present in the token. Entra ID client-credentials (app-only) tokens carry no user claim, so they authenticate as the calling application.
 * For `GroupBasedPolicy` support, the `groups` claim should be present in the access token (requires a "Group Membership" protocol mapper in Keycloak).
+* **Entra ID limitation**: Group claims use object IDs (GUIDs) instead of names, and are omitted entirely when a user exceeds the group overage threshold. GroupBasedPolicy must reference GUIDs and cannot be used for principals with large group memberships.
 
 (*) Please note that **the role match is case-sensitive**, e.g. the name of the role in the OIDC server and in the `Permission` configuration
 must be exactly the same.
@@ -69,6 +70,16 @@ For example, the access token for a client `app` of a user with `reader` role an
 }
 ```
 
+A Microsoft Entra ID (Azure AD) client-credentials (app-only) token has no user claim; the application authenticates as itself, and its app roles arrive in the top-level `roles` claim:
+```json
+{
+  "azp": "11111111-2222-3333-4444-555555555555",
+  "roles": [
+    "reader"
+  ]
+}
+```
+
 #### Server-Side Configuration
 
 The server requires `auth_discovery_url` and `client_id` to validate incoming JWT tokens via JWKS:

@@ -61,17 +61,29 @@ async def _validate_token(self, access_token: str):
 
     @staticmethod
     def _extract_username_or_raise_error(data: dict) -> str:
-        """Extract the username from the decoded JWT. Raises if missing — identity is mandatory.
-
-        Checks ``preferred_username`` first (Keycloak default), then falls back
-        to ``upn`` (Azure AD / Entra ID).
+        """Extract the username from the decoded JWT, or raise if the token
+        carries none of the recognised identity claims.
+
+        Human identity claims take precedence: ``preferred_username`` (Keycloak
+        default), then ``upn`` (Azure AD / Entra ID). Client-credentials
+        (app-only) tokens carry neither, so the calling application's own
+        identity is used instead: ``azp`` (Entra ID v2 tokens), ``appid``
+        (Entra ID v1 tokens), and finally ``sub``, which every issuer sets.
+        A claim present with a null or non-string value is skipped rather than
+        returned, so it never shadows a usable later claim. Because ``sub`` is a
+        mandatory string JWT claim, the raise below fires only for a malformed
+        token that provides none of the five as a string.
         """
-        if "preferred_username" in data:
-            return data["preferred_username"]
-        if "upn" in data:
-            return data["upn"]
+        for claim in ("preferred_username", "upn", "azp", "appid", "sub"):
+            value = data.get(claim)
+            if isinstance(value, str):
+                return value
+        logger.debug(
+            f"No usable username claim; token claims present: {list(data.keys())}"
+        )
         raise AuthenticationError(
-            "Missing preferred_username or upn field in access token."
+            "Missing username claim in access token: expected one of "
+            "preferred_username, upn, azp, appid or sub."
         )
 
     @staticmethod
@@ -194,6 +206,10 @@ async def user_details_from_access_token(self, access_token: str) -> User:
                 if self._auth_config.client_id
                 else []
             )
+            # Entra ID emits app roles in the top-level `roles` claim instead of
+            # Keycloak's nested `resource_access.<client_id>.roles`. Merge both
+            # shapes for every issuer, preserving order and dropping duplicates.
+            roles = list(dict.fromkeys(roles + self._extract_claim(data, "roles")))
             groups = self._extract_claim(data, "groups")
 
             logger.info(

@@ -1,3 +1,6 @@
+from typing import Dict
+from unittest.mock import MagicMock
+
 import pytest
 from kubernetes import client
 
@@ -62,6 +65,22 @@ def oidc_config() -> OidcAuthConfig:
     )
 
 
+@pytest.fixture
+def discovery_data() -> Dict[str, str]:
+    return {
+        "authorization_endpoint": "https://localhost:8080/realms/master/protocol/openid-connect/auth",
+        "token_endpoint": "https://localhost:8080/realms/master/protocol/openid-connect/token",
+        "jwks_uri": "https://localhost:8080/realms/master/protocol/openid-connect/certs",
+    }
+
+
+@pytest.fixture
+def signing_key() -> MagicMock:
+    key = MagicMock()
+    key.key = "a-key"
+    return key
+
+
 @pytest.fixture(
     scope="module",
     params=[