Configuration(yaml_files=[...]) (ets-labs#522)

* Add provider changes and tests

* Move config test fixtures

* Fix issue with explicit providing of envs_required=False for configuration from_*()

* Implement container API

* Increase priority of overriding from context

* Add docs and example

* Update changelog

* Update changelog

Author: rmk135

docs/main/changelog.rst

@@ -14,6 +14,9 @@ Develop
   ``container.wire(modules=["yourapp.module1"])``.
 - Add container wiring configuration ``wiring_config = containers.WiringConfiguration()``.
 - Add support of ``with`` statement for ``container.override_providers()`` method.
+- Add ``Configuration(yaml_files=[...])`` argument.
+- Fix ``envs_required=False`` behavior in ``Configuration.from_*()`` methods
+  to give a priority to the explicitly provided value.
 - Drop support of Python 3.4. There are no immediate breaking changes, but Dependency Injector
   will no longer be tested on Python 3.4 and any bugs will not be fixed.
 - Fix ``Dependency.is_defined`` attribute to always return boolean value.

docs/providers/configuration.rst

@@ -72,6 +72,20 @@ where ``examples/providers/configuration/config.yml`` is:
 .. literalinclude:: ../../examples/providers/configuration/config.yml
    :language: ini
 
+Alternatively, you can provide a path to the YAML file over the configuration provider argument. In that case,
+the container will call ``config.from_yaml()`` automatically:
+
+.. code-block:: python
+   :emphasize-lines: 3
+
+   class Container(containers.DeclarativeContainer):
+
+       config = providers.Configuration(yaml_files=["./config.yml"])
+
+
+   if __name__ == "__main__":
+       container = Container()  # Config is loaded from ./config.yml
+
 :py:meth:`Configuration.from_yaml` method supports environment variables interpolation.
 
 .. code-block:: ini

examples/providers/configuration/configuration_yaml_init.py

@@ -0,0 +1,25 @@
+"""`Configuration` provider values loading example."""
+
+from dependency_injector import containers, providers
+
+
+class Container(containers.DeclarativeContainer):
+
+    config = providers.Configuration(yaml_files=["./config.yml"])
+
+
+if __name__ == "__main__":
+    container = Container()
+
+    assert container.config() == {
+        "aws": {
+            "access_key_id": "KEY",
+            "secret_access_key": "SECRET",
+        },
+    }
+    assert container.config.aws() == {
+        "access_key_id": "KEY",
+        "secret_access_key": "SECRET",
+    }
+    assert container.config.aws.access_key_id() == "KEY"
+    assert container.config.aws.secret_access_key() == "SECRET"