Add prefix to AzureKeyCredential policy (Azure#29901)

* Add Http spec auth policy

* More types

* Fix typing

* Typing fix

* Fix import

* Add prefix to policy

* Typing

* Pylint

* Rename to scheme

* ChangLoge

* Rename to prefix

* Update CHANGELOG.md

sdk/core/azure-core/CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Features Added
 
 - Added support to use sync credentials in `AsyncBearerTokenCredentialPolicy`. #30381
+- Added "prefix" parameter to AzureKeyCredentialPolicy #29901
 
 ### Breaking Changes
 

sdk/core/azure-core/azure/core/pipeline/policies/_authentication.py

@@ -4,7 +4,7 @@
 # license information.
 # -------------------------------------------------------------------------
 import time
-from typing import TYPE_CHECKING, Dict, Optional
+from typing import TYPE_CHECKING, Dict, Optional, TypeVar
 
 from . import HTTPPolicy, SansIOHTTPPolicy
 from ...exceptions import ServiceRequestError
@@ -18,6 +18,9 @@
         AzureSasCredential,
     )
     from azure.core.pipeline import PipelineRequest, PipelineResponse
+    from azure.core.pipeline.policies._universal import HTTPRequestType
+
+HTTPResponseTypeVar = TypeVar("HTTPResponseTypeVar")
 
 
 # pylint:disable=too-few-public-methods
@@ -160,17 +163,23 @@ def on_exception(self, request: "PipelineRequest") -> None:
         return
 
 
-class AzureKeyCredentialPolicy(SansIOHTTPPolicy):
+class AzureKeyCredentialPolicy(SansIOHTTPPolicy["HTTPRequestType", HTTPResponseTypeVar]):
     """Adds a key header for the provided credential.
 
     :param credential: The credential used to authenticate requests.
     :type credential: ~azure.core.credentials.AzureKeyCredential
     :param str name: The name of the key header used for the credential.
+    :keyword str prefix: The name of the prefix for the header value if any.
     :raises: ValueError or TypeError
     """
 
     def __init__(
-        self, credential: "AzureKeyCredential", name: str, **kwargs  # pylint: disable=unused-argument
+        self,
+        credential: "AzureKeyCredential",
+        name: str,
+        *,
+        prefix: Optional[str] = None,
+        **kwargs,  # pylint: disable=unused-argument
     ) -> None:
         super(AzureKeyCredentialPolicy, self).__init__()
         self._credential = credential
@@ -179,9 +188,10 @@ def __init__(
         if not isinstance(name, str):
             raise TypeError("name must be a string.")
         self._name = name
+        self._prefix = prefix + " " if prefix else ""
 
-    def on_request(self, request):
-        request.http_request.headers[self._name] = self._credential.key
+    def on_request(self, request: "PipelineRequest[HTTPRequestType]") -> None:
+        request.http_request.headers[self._name] = f"{self._prefix}{self._credential.key}"
 
 
 class AzureSasCredentialPolicy(SansIOHTTPPolicy):

sdk/core/azure-core/tests/test_authentication.py

@@ -409,3 +409,22 @@ def test_azure_named_key_credential_raises():
 
     with pytest.raises(TypeError, match="Both name and key must be strings."):
         cred.update(1234, "newkey")
+
+
+@pytest.mark.parametrize("http_request", HTTP_REQUESTS)
+def test_azure_http_credential_policy(http_request):
+    """Tests to see if we can create an AzureHttpKeyCredentialPolicy"""
+
+    prefix = "SharedAccessKey"
+    api_key = "test_key"
+    header_content = f"{prefix} {api_key}"
+
+    def verify_authorization_header(request):
+        assert request.headers["Authorization"] == header_content
+
+    transport = Mock(send=verify_authorization_header)
+    credential = AzureKeyCredential(api_key)
+    credential_policy = AzureKeyCredentialPolicy(credential=credential, name="Authorization", prefix=prefix)
+    pipeline = Pipeline(transport=transport, policies=[credential_policy])
+
+    pipeline.run(http_request("GET", "https://test_key_credential"))