Implement async resources initialization in container

src/dependency_injector/containers.pyi

@@ -1,5 +1,17 @@
 from types import ModuleType
-from typing import Type, Dict, Tuple, Optional, Any, Union, ClassVar, Callable as _Callable, Iterable, TypeVar
+from typing import (
+    Type,
+    Dict,
+    Tuple,
+    Optional,
+    Any,
+    Union,
+    ClassVar,
+    Callable as _Callable,
+    Iterable,
+    TypeVar,
+    Awaitable,
+)
 
 from .providers import Provider
 
@@ -25,8 +37,8 @@ class Container:
     def resolve_provider_name(self, provider_to_resolve: Provider) -> Optional[str]: ...
     def wire(self, modules: Optional[Iterable[ModuleType]] = None, packages: Optional[Iterable[ModuleType]] = None) -> None: ...
     def unwire(self) -> None: ...
-    def init_resources(self) -> None: ...
-    def shutdown_resources(self) -> None: ...
+    def init_resources(self) -> Optional[Awaitable]: ...
+    def shutdown_resources(self) -> Optional[Awaitable]: ...
 
 
 class DynamicContainer(Container): ...

src/dependency_injector/containers.pyx

@@ -1,7 +1,13 @@
 """Containers module."""
 
+import inspect
 import sys
 
+try:
+    import asyncio
+except ImportError:
+    asyncio = None
+
 import six
 
 from .errors import Error
@@ -216,17 +222,33 @@ class DynamicContainer(object):
 
     def init_resources(self):
         """Initialize all container resources."""
+        futures = []
         for provider in self.providers.values():
             if not isinstance(provider, Resource):
                 continue
-            provider.init()
+
+            resource = provider.init()
+
+            if inspect.isawaitable(resource):
+                futures.append(resource)
+
+        if futures:
+            return asyncio.gather(*futures)
 
     def shutdown_resources(self):
         """Shutdown all container resources."""
+        futures = []
         for provider in self.providers.values():
             if not isinstance(provider, Resource):
                 continue
-            provider.shutdown()
+
+            shutdown = provider.shutdown()
+
+            if inspect.isawaitable(shutdown):
+                futures.append(shutdown)
+
+        if futures:
+            return asyncio.gather(*futures)
 
 
 class DeclarativeContainerMetaClass(type):

tests/unit/containers/test_dynamic_py2_py3.py

@@ -2,6 +2,19 @@
 
 import unittest2 as unittest
 
+# Runtime import to get asyncutils module
+import os
+_TOP_DIR = os.path.abspath(
+    os.path.sep.join((
+        os.path.dirname(__file__),
+        '../',
+    )),
+)
+import sys
+sys.path.append(_TOP_DIR)
+
+from asyncutils import AsyncTestCase
+
 from dependency_injector import (
     containers,
     providers,
@@ -233,5 +246,55 @@ class DeclarativeContainerInstanceTests(unittest.TestCase):
         self.assertEqual(_init2.shutdown_counter, 2)
 
 
+class AsyncResourcesInitializationTest(AsyncTestCase):
+
+    @unittest.skipIf(sys.version_info[:2] <= (3, 5), 'Async test')
+    def test_async_init_resources(self):
+        async def _init1():
+            _init1.init_counter += 1
+            yield
+            _init1.shutdown_counter += 1
+
+        _init1.init_counter = 0
+        _init1.shutdown_counter = 0
+
+        async def _init2():
+            _init2.init_counter += 1
+            yield
+            _init2.shutdown_counter += 1
+
+        _init2.init_counter = 0
+        _init2.shutdown_counter = 0
+
+        class Container(containers.DeclarativeContainer):
+            resource1 = providers.Resource(_init1)
+            resource2 = providers.Resource(_init2)
+
+        container = Container()
+        self.assertEqual(_init1.init_counter, 0)
+        self.assertEqual(_init1.shutdown_counter, 0)
+        self.assertEqual(_init2.init_counter, 0)
+        self.assertEqual(_init2.shutdown_counter, 0)
+
+        self._run(container.init_resources())
+        self.assertEqual(_init1.init_counter, 1)
+        self.assertEqual(_init1.shutdown_counter, 0)
+        self.assertEqual(_init2.init_counter, 1)
+        self.assertEqual(_init2.shutdown_counter, 0)
+
+        self._run(container.shutdown_resources())
+        self.assertEqual(_init1.init_counter, 1)
+        self.assertEqual(_init1.shutdown_counter, 1)
+        self.assertEqual(_init2.init_counter, 1)
+        self.assertEqual(_init2.shutdown_counter, 1)
+
+        self._run(container.init_resources())
+        self._run(container.shutdown_resources())
+        self.assertEqual(_init1.init_counter, 2)
+        self.assertEqual(_init1.shutdown_counter, 2)
+        self.assertEqual(_init2.init_counter, 2)
+        self.assertEqual(_init2.shutdown_counter, 2)
+
+
 if __name__ == '__main__':
     unittest.main()