Add ExternalHttpFunctionApp (#176)

* Add ExternalHttpFunctionApp

* fix err

* fix type hint

* fix linting

* fix linting

* fix linting

* add test

* declare as abstract

* make externalhttpapp methods raise unimplementederror

* fix err

---------

Co-authored-by: Bill Wang <[email protected]>

Author: YunchuWang

azure/functions/decorators/__init__.py

@@ -2,8 +2,8 @@
 #  Licensed under the MIT License.
 from .core import Cardinality, AccessRights
 from .function_app import FunctionApp, Function, DecoratorApi, DataType, \
-    AuthLevel, Blueprint, AsgiFunctionApp, WsgiFunctionApp, \
-    FunctionRegister, TriggerApi, BindingApi
+    AuthLevel, Blueprint, ExternalHttpFunctionApp, AsgiFunctionApp, \
+    WsgiFunctionApp, FunctionRegister, TriggerApi, BindingApi
 from .http import HttpMethod
 
 __all__ = [
@@ -14,6 +14,7 @@
     'TriggerApi',
     'BindingApi',
     'Blueprint',
+    'ExternalHttpFunctionApp',
     'AsgiFunctionApp',
     'WsgiFunctionApp',
     'DataType',

azure/functions/decorators/function_app.py

@@ -1,5 +1,6 @@
 #  Copyright (c) Microsoft Corporation. All rights reserved.
 #  Licensed under the MIT License.
+import abc
 import json
 import logging
 from abc import ABC
@@ -254,8 +255,7 @@ def app_script_file(self) -> str:
         return self._app_script_file
 
     def _validate_type(self,
-                       func: Union[Callable[..., Any],
-                                   FunctionBuilder]) \
+                       func: Union[Callable[..., Any], FunctionBuilder]) \
             -> FunctionBuilder:
         """Validate the type of the function object and return the created
         :class:`FunctionBuilder` object.
@@ -817,7 +817,7 @@ def cosmos_db_trigger_v3(self,
             lease_collection_name=lease_collection_name,
             lease_connection_string_setting=lease_connection_string_setting,
             lease_database_name=lease_database_name,
-            create_lease_collection_if_not_exists=create_lease_collection_if_not_exists, # NoQA
+            create_lease_collection_if_not_exists=create_lease_collection_if_not_exists,  # NoQA
             leases_collection_throughput=leases_collection_throughput,
             lease_collection_prefix=lease_collection_prefix,
             checkpoint_interval=checkpoint_interval,
@@ -2014,7 +2014,24 @@ class Blueprint(TriggerApi, BindingApi):
     pass
 
 
-class AsgiFunctionApp(FunctionRegister, TriggerApi):
+class ExternalHttpFunctionApp(FunctionRegister, TriggerApi, ABC):
+    """Interface to extend for building third party http function apps."""
+
+    @abc.abstractmethod
+    def _add_http_app(self,
+                      http_middleware: Union[
+                          AsgiMiddleware, WsgiMiddleware]) -> None:
+        """Add a Wsgi or Asgi app integrated http function.
+
+        :param http_middleware: :class:`WsgiMiddleware`
+                                or class:`AsgiMiddleware` instance.
+
+        :return: None
+        """
+        raise NotImplementedError()
+
+
+class AsgiFunctionApp(ExternalHttpFunctionApp):
     def __init__(self, app,
                  http_auth_level: Union[AuthLevel, str] = AuthLevel.FUNCTION):
         """Constructor of :class:`AsgiFunctionApp` object.
@@ -2027,13 +2044,21 @@ def __init__(self, app,
         super().__init__(auth_level=http_auth_level)
         self._add_http_app(AsgiMiddleware(app))
 
-    def _add_http_app(self, asgi_middleware: AsgiMiddleware) -> None:
+    def _add_http_app(self,
+                      http_middleware: Union[
+                          AsgiMiddleware, WsgiMiddleware]) -> None:
         """Add an Asgi app integrated http function.
 
-        :param asgi_middleware: :class:`AsgiMiddleware` instance.
+        :param http_middleware: :class:`WsgiMiddleware`
+                                or class:`AsgiMiddleware` instance.
 
         :return: None
         """
+        if not isinstance(http_middleware, AsgiMiddleware):
+            raise TypeError("Please pass AsgiMiddleware instance"
+                            " as parameter.")
+
+        asgi_middleware: AsgiMiddleware = http_middleware
 
         @self.http_type(http_type='asgi')
         @self.route(methods=(method for method in HttpMethod),
@@ -2043,7 +2068,7 @@ async def http_app_func(req: HttpRequest, context: Context):
             return await asgi_middleware.handle_async(req, context)
 
 
-class WsgiFunctionApp(FunctionRegister, TriggerApi):
+class WsgiFunctionApp(ExternalHttpFunctionApp):
     def __init__(self, app,
                  http_auth_level: Union[AuthLevel, str] = AuthLevel.FUNCTION):
         """Constructor of :class:`WsgiFunctionApp` object.
@@ -2054,13 +2079,20 @@ def __init__(self, app,
         self._add_http_app(WsgiMiddleware(app))
 
     def _add_http_app(self,
-                      wsgi_middleware: WsgiMiddleware) -> None:
+                      http_middleware: Union[
+                          AsgiMiddleware, WsgiMiddleware]) -> None:
         """Add a Wsgi app integrated http function.
 
-        :param wsgi_middleware: :class:`WsgiMiddleware` instance.
+        :param http_middleware: :class:`WsgiMiddleware`
+                                or class:`AsgiMiddleware` instance.
 
         :return: None
         """
+        if not isinstance(http_middleware, WsgiMiddleware):
+            raise TypeError("Please pass WsgiMiddleware instance"
+                            " as parameter.")
+
+        wsgi_middleware: WsgiMiddleware = http_middleware
 
         @self.http_type(http_type='wsgi')
         @self.route(methods=(method for method in HttpMethod),

tests/decorators/test_function_app.py

@@ -4,6 +4,7 @@
 import json
 import unittest
 from unittest import mock
+from unittest.mock import patch
 
 from azure.functions import WsgiMiddleware, AsgiMiddleware
 from azure.functions.decorators.constants import HTTP_OUTPUT, HTTP_TRIGGER, \
@@ -12,7 +13,8 @@
     BindingDirection, SCRIPT_FILE_NAME
 from azure.functions.decorators.function_app import FunctionBuilder, \
     FunctionApp, Function, Blueprint, DecoratorApi, AsgiFunctionApp, \
-    WsgiFunctionApp, HttpFunctionsAuthLevelMixin, FunctionRegister, TriggerApi
+    WsgiFunctionApp, HttpFunctionsAuthLevelMixin, FunctionRegister, \
+    TriggerApi, ExternalHttpFunctionApp
 from azure.functions.decorators.http import HttpTrigger, HttpOutput, \
     HttpMethod
 from tests.decorators.test_core import DummyTrigger
@@ -527,6 +529,31 @@ def test_wsgi_function_app_is_http_function(self):
         self.assertEqual(len(funcs), 1)
         self.assertTrue(funcs[0].is_http_function())
 
+    def test_asgi_function_app_add_wsgi_app(self):
+        with self.assertRaises(TypeError) as err:
+            app = AsgiFunctionApp(app=object(),
+                                  http_auth_level=AuthLevel.ANONYMOUS)
+            app._add_http_app(WsgiMiddleware(object()))
+
+        self.assertEqual(err.exception.args[0],
+                         "Please pass AsgiMiddleware instance as parameter.")
+
+    def test_wsgi_function_app_add_asgi_app(self):
+        with self.assertRaises(TypeError) as err:
+            app = WsgiFunctionApp(app=object(),
+                                  http_auth_level=AuthLevel.ANONYMOUS)
+            app._add_http_app(AsgiMiddleware(object()))
+
+        self.assertEqual(err.exception.args[0],
+                         "Please pass WsgiMiddleware instance as parameter.")
+
+    @patch("azure.functions.decorators.function_app.ExternalHttpFunctionApp"
+           ".__abstractmethods__", set())
+    def test_external_http_function_app(self):
+        with self.assertRaises(NotImplementedError):
+            app = ExternalHttpFunctionApp(auth_level=AuthLevel.ANONYMOUS)
+            app._add_http_app(AsgiMiddleware(object()))
+
     def _test_http_external_app(self, app, is_async):
         funcs = app.get_functions()
         self.assertEqual(len(funcs), 1)