Add get_metrics command to n2vc_juju_conn and libjuju

Change-Id: I6cde1528579c8ca7aa72d935c5e570004468bb1a
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/n2vc/libjuju.py b/n2vc/libjuju.py
index 12730fd..d761adc 100644
--- a/n2vc/libjuju.py
+++ b/n2vc/libjuju.py
@@ -711,6 +711,26 @@
             await self.disconnect_model(model)
             await self.disconnect_controller(controller)
 
+    async def get_metrics(self, model_name: str, application_name: str) -> dict:
+        """Get the metrics collected by the VCA.
+
+        :param model_name The name or unique id of the network service
+        :param application_name The name of the application
+        """
+        if not model_name or not application_name:
+            raise Exception("model_name and application_name must be non-empty strings")
+        metrics = {}
+        controller = await self.get_controller()
+        model = await self.get_model(controller, model_name)
+        try:
+            application = self._get_application(model, application_name)
+            if application is not None:
+                metrics = await application.get_metrics()
+        finally:
+            self.disconnect_model(model)
+            self.disconnect_controller(controller)
+        return metrics
+
     async def add_relation(
         self, model_name: str, endpoint_1: str, endpoint_2: str,
     ):