Fix `APIKey**` security schemes status code on "Not authenticated" error

fastapi/security/api_key.py

@@ -1,11 +1,11 @@
-from typing import Optional, Union
+from typing import Literal, Optional, Union
 
 from fastapi.openapi.models import APIKey, APIKeyIn
 from fastapi.security.base import SecurityBase
 from starlette.exceptions import HTTPException
 from starlette.requests import Request
-from starlette.status import HTTP_403_FORBIDDEN
+from starlette.status import HTTP_401_UNAUTHORIZED, HTTP_403_FORBIDDEN
-from typing_extensions import Annotated, Doc
+from typing_extensions import Annotated, Doc, deprecated
 
 
 class APIKeyBase(SecurityBase):
@@ -16,10 +16,13 @@ class APIKeyBase(SecurityBase):
         description: Union[str, None],
         scheme_name: Union[str, None],
         auto_error: bool,
+        not_authenticated_status_code: Literal[401, 403],
     ):
         self.parameter_location = location.value
         self.parameter_name = name
         self.auto_error = auto_error
+        self.not_authenticated_status_code = not_authenticated_status_code
+
         self.model: APIKey = APIKey(
             **{"in": location},  # type: ignore[arg-type]
             name=name,
@@ -27,12 +30,31 @@ class APIKeyBase(SecurityBase):
         )
         self.scheme_name = scheme_name or self.__class__.__name__
 
+    def format_www_authenticate_header_value(self) -> str:
+        """
+        The WWW-Authenticate header is not standardized for API Key authentication.
+        It's considered good practice to include information about the authentication
+        challange.
+        This method follows one of the common templates.
+        If a different format is required, override this method in a subclass.
+        """
+
+        return f'ApiKey in="{self.parameter_location}", name="{self.parameter_name}"'
+
     def check_api_key(self, api_key: Optional[str]) -> Optional[str]:
         if not api_key:
             if self.auto_error:
+                if self.not_authenticated_status_code == HTTP_403_FORBIDDEN:
                     raise HTTPException(
                         status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
                     )
+                else:  # By default use 401
+                    www_authenticate = self.format_www_authenticate_header_value()
+                    raise HTTPException(
+                        status_code=HTTP_401_UNAUTHORIZED,
+                        detail="Not authenticated",
+                        headers={"WWW-Authenticate": www_authenticate},
+                    )
             return None
         return api_key
 
@@ -115,6 +137,34 @@ class APIKeyQuery(APIKeyBase):
                 """
             ),
         ] = True,
+        not_authenticated_status_code: Annotated[
+            Literal[401, 403],
+            Doc(
+                """
+                By default, if the query parameter is not provided and `auto_error` is
+                set to `True`, `APIKeyQuery` will automatically raise an
+                `HTTPException` with the status code `401`.
+
+                If your client relies on the old (incorrect) behavior and expects the
+                status code to be `403`, you can set `not_authenticated_status_code` to
+                `403` to achieve it.
+
+                Keep in mind that this parameter is temporary and will be removed in
+                the near future.
+                Consider updating your clients to align with the new behavior.
+                """
+            ),
+            deprecated(
+                """
+                This parameter is temporary. It was introduced to give users time
+                to upgrade their clients to follow the new behavior and will eventually
+                be removed.
+
+                Use it as a short-term workaround, but consider updating your clients
+                to align with the new behavior.
+                """
+            ),
+        ] = 401,
     ):
         super().__init__(
             location=APIKeyIn.query,
@@ -122,6 +172,7 @@ class APIKeyQuery(APIKeyBase):
             scheme_name=scheme_name,
             description=description,
             auto_error=auto_error,
+            not_authenticated_status_code=not_authenticated_status_code,
         )
 
     async def __call__(self, request: Request) -> Optional[str]:
@@ -203,6 +254,34 @@ class APIKeyHeader(APIKeyBase):
                 """
             ),
         ] = True,
+        not_authenticated_status_code: Annotated[
+            Literal[401, 403],
+            Doc(
+                """
+                By default, if the header is not provided and `auto_error` is
+                set to `True`, `APIKeyHeader` will automatically raise an
+                `HTTPException` with the status code `401`.
+
+                If your client relies on the old (incorrect) behavior and expects the
+                status code to be `403`, you can set `not_authenticated_status_code` to
+                `403` to achieve it.
+
+                Keep in mind that this parameter is temporary and will be removed in
+                the near future.
+                Consider updating your clients to align with the new behavior.
+                """
+            ),
+            deprecated(
+                """
+                This parameter is temporary. It was introduced to give users time
+                to upgrade their clients to follow the new behavior and will eventually
+                be removed.
+
+                Use it as a short-term workaround, but consider updating your clients
+                to align with the new behavior.
+                """
+            ),
+        ] = 401,
     ):
         super().__init__(
             location=APIKeyIn.header,
@@ -210,6 +289,7 @@ class APIKeyHeader(APIKeyBase):
             scheme_name=scheme_name,
             description=description,
             auto_error=auto_error,
+            not_authenticated_status_code=not_authenticated_status_code,
         )
 
     async def __call__(self, request: Request) -> Optional[str]:
@@ -291,6 +371,34 @@ class APIKeyCookie(APIKeyBase):
                 """
             ),
         ] = True,
+        not_authenticated_status_code: Annotated[
+            Literal[401, 403],
+            Doc(
+                """
+                By default, if the cookie is not provided and `auto_error` is
+                set to `True`, `APIKeyCookie` will automatically raise an
+                `HTTPException` with the status code `401`.
+
+                If your client relies on the old (incorrect) behavior and expects the
+                status code to be `403`, you can set `not_authenticated_status_code` to
+                `403` to achieve it.
+
+                Keep in mind that this parameter is temporary and will be removed in
+                the near future.
+                Consider updating your clients to align with the new behavior.
+                """
+            ),
+            deprecated(
+                """
+                This parameter is temporary. It was introduced to give users time
+                to upgrade their clients to follow the new behavior and will eventually
+                be removed.
+
+                Use it as a short-term workaround, but consider updating your clients
+                to align with the new behavior.
+                """
+            ),
+        ] = 401,
     ):
         super().__init__(
             location=APIKeyIn.cookie,
@@ -298,6 +406,7 @@ class APIKeyCookie(APIKeyBase):
             scheme_name=scheme_name,
             description=description,
             auto_error=auto_error,
+            not_authenticated_status_code=not_authenticated_status_code,
         )
 
     async def __call__(self, request: Request) -> Optional[str]:

tests/test_security_api_key_cookie.py

@@ -32,8 +32,9 @@ def test_security_api_key():
 def test_security_api_key_no_key():
     client = TestClient(app)
     response = client.get("/users/me")
-    assert response.status_code == 403, response.text
+    assert response.status_code == 401, response.text
     assert response.json() == {"detail": "Not authenticated"}
+    assert response.headers["WWW-Authenticate"] == 'ApiKey in="cookie", name="key"'
 
 
 def test_openapi_schema():

tests/test_security_api_key_cookie_description.py

@@ -32,8 +32,9 @@ def test_security_api_key():
 def test_security_api_key_no_key():
     client = TestClient(app)
     response = client.get("/users/me")
-    assert response.status_code == 403, response.text
+    assert response.status_code == 401, response.text
     assert response.json() == {"detail": "Not authenticated"}
+    assert response.headers["WWW-Authenticate"] == 'ApiKey in="cookie", name="key"'
 
 
 def test_openapi_schema():

tests/test_security_api_key_header.py

@@ -33,8 +33,9 @@ def test_security_api_key():
 
 def test_security_api_key_no_key():
     response = client.get("/users/me")
-    assert response.status_code == 403, response.text
+    assert response.status_code == 401, response.text
     assert response.json() == {"detail": "Not authenticated"}
+    assert response.headers["WWW-Authenticate"] == 'ApiKey in="header", name="key"'
 
 
 def test_openapi_schema():

tests/test_security_api_key_header_description.py

@@ -33,8 +33,9 @@ def test_security_api_key():
 
 def test_security_api_key_no_key():
     response = client.get("/users/me")
-    assert response.status_code == 403, response.text
+    assert response.status_code == 401, response.text
     assert response.json() == {"detail": "Not authenticated"}
+    assert response.headers["WWW-Authenticate"] == 'ApiKey in="header", name="key"'
 
 
 def test_openapi_schema():

tests/test_security_api_key_query.py

@@ -33,8 +33,9 @@ def test_security_api_key():
 
 def test_security_api_key_no_key():
     response = client.get("/users/me")
-    assert response.status_code == 403, response.text
+    assert response.status_code == 401, response.text
     assert response.json() == {"detail": "Not authenticated"}
+    assert response.headers["WWW-Authenticate"] == 'ApiKey in="query", name="key"'
 
 
 def test_openapi_schema():

tests/test_security_api_key_query_description.py

@@ -33,8 +33,9 @@ def test_security_api_key():
 
 def test_security_api_key_no_key():
     response = client.get("/users/me")
-    assert response.status_code == 403, response.text
+    assert response.status_code == 401, response.text
     assert response.json() == {"detail": "Not authenticated"}
+    assert response.headers["WWW-Authenticate"] == 'ApiKey in="query", name="key"'
 
 
 def test_openapi_schema():

tests/test_security_status_code_403_option.py

@@ -0,0 +1,56 @@
+import pytest
+from fastapi import FastAPI, Security
+from fastapi.security.api_key import APIKeyBase, APIKeyCookie, APIKeyHeader, APIKeyQuery
+from fastapi.testclient import TestClient
+
+
+@pytest.mark.parametrize(
+    "auth",
+    [
+        APIKeyQuery(name="key", not_authenticated_status_code=403),
+        APIKeyHeader(name="key", not_authenticated_status_code=403),
+        APIKeyCookie(name="key", not_authenticated_status_code=403),
+    ],
+)
+def test_apikey_status_code_403_on_auth_error(auth: APIKeyBase):
+    """
+    Test temporary `not_authenticated_status_code` parameter for APIKey** classes.
+    """
+
+    app = FastAPI()
+
+    @app.get("/")
+    async def protected(_: str = Security(auth)):
+        pass  # pragma: no cover
+
+    client = TestClient(app)
+
+    response = client.get("/")
+    assert response.status_code == 403
+    assert response.json() == {"detail": "Not authenticated"}
+
+
+@pytest.mark.parametrize(
+    "auth",
+    [
+        APIKeyQuery(name="key", not_authenticated_status_code=403, auto_error=False),
+        APIKeyHeader(name="key", not_authenticated_status_code=403, auto_error=False),
+        APIKeyCookie(name="key", not_authenticated_status_code=403, auto_error=False),
+    ],
+)
+def test_apikey_status_code_403_on_auth_error_no_auto_error(auth: APIKeyBase):
+    """
+    Test temporary `not_authenticated_status_code` parameter for APIKey** classes with
+    `auto_error=False`.
+    """
+
+    app = FastAPI()
+
+    @app.get("/")
+    async def protected(_: str = Security(auth)):
+        pass  # pragma: no cover
+
+    client = TestClient(app)
+
+    response = client.get("/")
+    assert response.status_code == 200