Add durable functions support

azure_functions_worker/bindings/__init__.py

@@ -2,6 +2,7 @@
 from .context import Context
 from .meta import check_input_type_annotation
 from .meta import check_output_type_annotation
+from .meta import has_implicit_output
 from .meta import is_trigger_binding
 from .meta import from_incoming_proto, to_outgoing_proto
 from .out import Out
@@ -11,5 +12,6 @@
     'Out', 'Context',
     'is_trigger_binding',
     'check_input_type_annotation', 'check_output_type_annotation',
+    'has_implicit_output',
     'from_incoming_proto', 'to_outgoing_proto', 'TraceContext',
 )

azure_functions_worker/bindings/generic.py

@@ -46,3 +46,7 @@ def decode(cls, data: datumdef.Datum, *, trigger_metadata) -> typing.Any:
             )
 
         return result
+
+    @classmethod
+    def has_implicit_output(cls) -> bool:
+        return False

azure_functions_worker/bindings/meta.py

@@ -9,18 +9,19 @@
 
 def get_binding_registry():
     func = sys.modules.get('azure.functions')
-    if func is not None:
-        return func.get_binding_registry()
-    else:
-        return None
+
+    # If fails to acquire customer's BYO azure-functions, load the builtin
+    if func is None:
+        import azure.functions as func
+
+    return func.get_binding_registry()
 
 
 def get_binding(bind_name: str) -> object:
     binding = None
     registry = get_binding_registry()
     if registry is not None:
         binding = registry.get(bind_name)
-
     if binding is None:
         binding = generic.GenericBinding
 
@@ -32,16 +33,24 @@ def is_trigger_binding(bind_name: str) -> bool:
     return binding.has_trigger_support()
 
 
-def check_input_type_annotation(binding: str, pytype: type) -> bool:
-    binding = get_binding(binding)
+def check_input_type_annotation(bind_name: str, pytype: type) -> bool:
+    binding = get_binding(bind_name)
     return binding.check_input_type_annotation(pytype)
 
 
-def check_output_type_annotation(binding: str, pytype: type) -> bool:
-    binding = get_binding(binding)
+def check_output_type_annotation(bind_name: str, pytype: type) -> bool:
+    binding = get_binding(bind_name)
     return binding.check_output_type_annotation(pytype)
 
 
+def has_implicit_output(bind_name: str) -> bool:
+    binding = get_binding(bind_name)
+
+    # If the binding does not have metaclass of meta.InConverter
+    # The implicit_output does not exist
+    return getattr(binding, 'has_implicit_output', lambda: False)()
+
+
 def from_incoming_proto(
         binding: str,
         val: protos.TypedData, *,

azure_functions_worker/functions.py

@@ -82,6 +82,13 @@ def add_function(self, function_id: str,
                 assert return_binding_name is not None
 
                 has_return = True
+            elif bindings.has_implicit_output(desc.type):
+                # If the binding specify implicit output binding
+                # (e.g. orchestrationTrigger, activityTrigger)
+                # we should enable output even if $return is not specified
+                has_return = True
+                return_binding_name = f'{desc.type}_ret'
+                bound_params[name] = desc
             else:
                 bound_params[name] = desc
 
@@ -180,7 +187,8 @@ def add_function(self, function_id: str,
                     f'direction in function.json, but its annotation '
                     f'is azure.functions.Out in Python')
 
-            if param_has_anno and param_py_type in (str, bytes):
+            if param_has_anno and param_py_type in (str, bytes) and (
+                    not bindings.has_implicit_output(desc.type)):
                 param_bind_type = 'generic'
             else:
                 param_bind_type = desc.type

setup.py

@@ -279,7 +279,7 @@ def run(self):
     ],
     extras_require={
         'dev': [
-            'azure-functions==1.1.0',
+            'azure-functions==1.2.0b1',
             'flake8~=3.7.9',
             'mypy',
             'pytest',