diff --git a/composer.json b/composer.json
index 25399e795..9cfb99af8 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         }
     ],
     "require": {
-        "dhii/module-interface": "0.2.x-dev",
+        "dhii/module-interface": "0.1",
         "psr/container": "^1.0",
         "oomphinc/composer-installers-extender": "^1.1",
         "container-interop/service-provider": "^0.4.0",
diff --git a/modules/ppcp-admin-notices/src/class-adminnotices.php b/modules/ppcp-admin-notices/src/class-adminnotices.php
index 1cc89e173..e8ae55b47 100644
--- a/modules/ppcp-admin-notices/src/class-adminnotices.php
+++ b/modules/ppcp-admin-notices/src/class-adminnotices.php
@@ -36,7 +36,7 @@ class AdminNotices implements ModuleInterface {
 	 *
 	 * @param ContainerInterface $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 		add_action(
 			'admin_notices',
 			function() use ( $container ) {
@@ -45,4 +45,12 @@ class AdminNotices implements ModuleInterface {
 			}
 		);
 	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/ppcp-api-client/src/class-apimodule.php b/modules/ppcp-api-client/src/class-apimodule.php
index f944a0245..9b466f87b 100644
--- a/modules/ppcp-api-client/src/class-apimodule.php
+++ b/modules/ppcp-api-client/src/class-apimodule.php
@@ -37,6 +37,14 @@ class ApiModule implements ModuleInterface {
 	 *
 	 * @param ContainerInterface $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
+	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
 	}
 }
diff --git a/modules/ppcp-button/src/class-buttonmodule.php b/modules/ppcp-button/src/class-buttonmodule.php
index 352ec54e2..8d06a91fe 100644
--- a/modules/ppcp-button/src/class-buttonmodule.php
+++ b/modules/ppcp-button/src/class-buttonmodule.php
@@ -41,9 +41,9 @@ class ButtonModule implements ModuleInterface {
 	/**
 	 * Runs the module.
 	 *
-	 * @param ContainerInterface $container The Container.
+	 * @param ContainerInterface|null $container The Container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 
 		add_action(
 			'wp',
@@ -151,4 +151,12 @@ class ButtonModule implements ModuleInterface {
 			}
 		);
 	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/ppcp-onboarding/src/class-onboardingmodule.php b/modules/ppcp-onboarding/src/class-onboardingmodule.php
index bf757eec6..3613ea1f7 100644
--- a/modules/ppcp-onboarding/src/class-onboardingmodule.php
+++ b/modules/ppcp-onboarding/src/class-onboardingmodule.php
@@ -38,9 +38,9 @@ class OnboardingModule implements ModuleInterface {
 	/**
 	 * Runs the module.
 	 *
-	 * @param ContainerInterface $container The container.
+	 * @param ContainerInterface|null $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 
 		$asset_loader = $container->get( 'onboarding.assets' );
 		/**
@@ -100,4 +100,12 @@ class OnboardingModule implements ModuleInterface {
 			}
 		);
 	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/ppcp-session/src/class-sessionmodule.php b/modules/ppcp-session/src/class-sessionmodule.php
index ee145e64b..8e1d97055 100644
--- a/modules/ppcp-session/src/class-sessionmodule.php
+++ b/modules/ppcp-session/src/class-sessionmodule.php
@@ -35,9 +35,9 @@ class SessionModule implements ModuleInterface {
 	/**
 	 * Run the module.
 	 *
-	 * @param ContainerInterface $container The container.
+	 * @param ContainerInterface|null $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 		add_action(
 			'woocommerce_init',
 			function () use ( $container ) {
@@ -51,4 +51,12 @@ class SessionModule implements ModuleInterface {
 			}
 		);
 	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/ppcp-subscription/src/class-subscriptionmodule.php b/modules/ppcp-subscription/src/class-subscriptionmodule.php
index abc4ea881..a87c93213 100644
--- a/modules/ppcp-subscription/src/class-subscriptionmodule.php
+++ b/modules/ppcp-subscription/src/class-subscriptionmodule.php
@@ -35,9 +35,9 @@ class SubscriptionModule implements ModuleInterface {
 	/**
 	 * Runs the module.
 	 *
-	 * @param ContainerInterface $container The container.
+	 * @param ContainerInterface|null $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 		add_action(
 			'woocommerce_scheduled_subscription_payment_' . PayPalGateway::ID,
 			static function ( $amount, $order ) use ( $container ) {
@@ -51,4 +51,12 @@ class SubscriptionModule implements ModuleInterface {
 			2
 		);
 	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/ppcp-wc-gateway/src/class-wcgatewaymodule.php b/modules/ppcp-wc-gateway/src/class-wcgatewaymodule.php
index adb736a5a..577fb1512 100644
--- a/modules/ppcp-wc-gateway/src/class-wcgatewaymodule.php
+++ b/modules/ppcp-wc-gateway/src/class-wcgatewaymodule.php
@@ -49,9 +49,9 @@ class WcGatewayModule implements ModuleInterface {
 	/**
 	 * Runs the module.
 	 *
-	 * @param ContainerInterface $container The container.
+	 * @param ContainerInterface|null $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 		$this->register_payment_gateways( $container );
 		$this->register_order_functionality( $container );
 		$this->register_columns( $container );
@@ -164,9 +164,9 @@ class WcGatewayModule implements ModuleInterface {
 	/**
 	 * Registers the payment gateways.
 	 *
-	 * @param ContainerInterface $container The container.
+	 * @param ContainerInterface|null $container The container.
 	 */
-	private function register_payment_gateways( ContainerInterface $container ) {
+	private function register_payment_gateways( ContainerInterface $container = null ) {
 
 		add_filter(
 			'woocommerce_payment_gateways',
@@ -356,4 +356,13 @@ class WcGatewayModule implements ModuleInterface {
 			2
 		);
 	}
+
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/ppcp-webhooks/src/class-webhookmodule.php b/modules/ppcp-webhooks/src/class-webhookmodule.php
index 6f43adadd..4156f816c 100644
--- a/modules/ppcp-webhooks/src/class-webhookmodule.php
+++ b/modules/ppcp-webhooks/src/class-webhookmodule.php
@@ -34,9 +34,9 @@ class WebhookModule implements ModuleInterface {
 	/**
 	 * Run the Webhook module.
 	 *
-	 * @param ContainerInterface $container The Container.
+	 * @param ContainerInterface|null $container The Container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
 		add_action(
 			'rest_api_init',
 			static function () use ( $container ) {
@@ -76,4 +76,12 @@ class WebhookModule implements ModuleInterface {
 			}
 		);
 	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
+	}
 }
diff --git a/modules/woocommerce-logging/src/class-woocommerceloggingmodule.php b/modules/woocommerce-logging/src/class-woocommerceloggingmodule.php
index ce135da89..aa629b5c8 100644
--- a/modules/woocommerce-logging/src/class-woocommerceloggingmodule.php
+++ b/modules/woocommerce-logging/src/class-woocommerceloggingmodule.php
@@ -36,6 +36,15 @@ class WooCommerceLoggingModule implements ModuleInterface {
 	 *
 	 * @param ContainerInterface $container The container.
 	 */
-	public function run( ContainerInterface $container ) {
+	public function run( ContainerInterface $container = null ) {
+	}
+
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
 	}
 }
diff --git a/src/class-pluginmodule.php b/src/class-pluginmodule.php
index df74ca27a..b961c4878 100644
--- a/src/class-pluginmodule.php
+++ b/src/class-pluginmodule.php
@@ -29,9 +29,16 @@ class PluginModule implements ModuleInterface {
 	/**
 	 * Runs the module.
 	 *
-	 * @param ContainerInterface $container The Container.
+	 * @param ContainerInterface|null $container The Container.
 	 */
-	public function run( ContainerInterface $container ) {
-		// TODO: Implement run() method.
+	public function run( ContainerInterface $container = null ) {
+	}
+
+	/**
+	 * Returns the key for the module.
+	 *
+	 * @return string|void
+	 */
+	public function getKey() {
 	}
 }