Merge "Relation support for multi-charm VNFs"
[osm/N2VC.git] / n2vc / vnf.py
index 899e407..a60f36c 100644 (file)
@@ -1,11 +1,13 @@
-
+import asyncio
 import logging
 import os
 import os.path
 import re
+import shlex
 import ssl
+import subprocess
 import sys
-import time
+import time
 
 # FIXME: this should load the juju inside or modules without having to
 # explicitly install it. Check why it's not working.
@@ -16,8 +18,8 @@ if path not in sys.path:
     sys.path.insert(1, path)
 
 from juju.controller import Controller
-from juju.model import Model, ModelObserver
-
+from juju.model import ModelObserver
+from juju.errors import JujuAPIError
 
 # We might need this to connect to the websocket securely, but test and verify.
 try:
@@ -36,6 +38,7 @@ class JujuCharmNotFound(Exception):
 class JujuApplicationExists(Exception):
     """The Application already exists."""
 
+
 class N2VCPrimitiveExecutionFailed(Exception):
     """Something failed while attempting to execute a primitive."""
 
@@ -46,44 +49,67 @@ logging.getLogger('juju.client.connection').setLevel(logging.WARN)
 logging.getLogger('juju.model').setLevel(logging.WARN)
 logging.getLogger('juju.machine').setLevel(logging.WARN)
 
+
 class VCAMonitor(ModelObserver):
     """Monitor state changes within the Juju Model."""
-    callback = None
-    callback_args = None
     log = None
     ns_name = None
-    application_name = None
+    applications = {}
 
-    def __init__(self, ns_name, application_name, callback, *args):
+    def __init__(self, ns_name):
         self.log = logging.getLogger(__name__)
 
         self.ns_name = ns_name
-        self.application_name = application_name
-        self.callback = callback
-        self.callback_args = args
+
+    def AddApplication(self, application_name, callback, *callback_args):
+        if application_name not in self.applications:
+            self.applications[application_name] = {
+                'callback': callback,
+                'callback_args': callback_args
+            }
+
+    def RemoveApplication(self, application_name):
+        if application_name in self.applications:
+            del self.applications[application_name]
 
     async def on_change(self, delta, old, new, model):
         """React to changes in the Juju model."""
 
         if delta.entity == "unit":
+            # Ignore change events from other applications
+            if delta.data['application'] not in self.applications.keys():
+                return
+
             try:
+
+                application_name = delta.data['application']
+
+                callback = self.applications[application_name]['callback']
+                callback_args = \
+                    self.applications[application_name]['callback_args']
+
                 if old and new:
-                    old_status = old.workload_status
-                    new_status = new.workload_status
-
-                    if old_status == new_status:
-
-                        """The workload status may fluctuate around certain events,
-                        so wait until the status has stabilized before triggering
-                        the callback."""
-                        if self.callback:
-                            self.callback(
-                                self.ns_name,
-                                self.application_name,
-                                new_status,
-                                *self.callback_args)
+                    # Fire off a callback with the application state
+                    if callback:
+                        callback(
+                            self.ns_name,
+                            delta.data['application'],
+                            new.workload_status,
+                            new.workload_status_message,
+                            *callback_args)
+
+                if old and not new:
+                    # This is a charm being removed
+                    if callback:
+                        callback(
+                            self.ns_name,
+                            delta.data['application'],
+                            "removed",
+                            "",
+                            *callback_args)
             except Exception as e:
-                self.log.debug("[1] notify_callback exception {}".format(e))
+                self.log.debug("[1] notify_callback exception: {}".format(e))
+
         elif delta.entity == "action":
             # TODO: Decide how we want to notify the user of actions
 
@@ -108,34 +134,16 @@ class VCAMonitor(ModelObserver):
 # Create unique models per network service
 # Document all public functions
 
-class N2VC:
-
-    # Juju API
-    api = None
-    log = None
-    controller = None
-    connecting = False
-    authenticated = False
-
-    models = {}
-    default_model = None
-
-    # Model Observers
-    monitors = {}
-
-    # VCA config
-    hostname = ""
-    port = 17070
-    username = ""
-    secret = ""
 
+class N2VC:
     def __init__(self,
                  log=None,
                  server='127.0.0.1',
                  port=17070,
                  user='admin',
                  secret=None,
-                 artifacts=None
+                 artifacts=None,
+                 loop=None,
                  ):
         """Initialize N2VC
 
@@ -152,9 +160,33 @@ class N2VC:
             'port': 17070,
             'artifacts': '/path/to/charms'
         })
-
         """
 
+        # Initialize instance-level variables
+        self.api = None
+        self.log = None
+        self.controller = None
+        self.connecting = False
+        self.authenticated = False
+
+        # For debugging
+        self.refcount = {
+            'controller': 0,
+            'model': 0,
+        }
+
+        self.models = {}
+        self.default_model = None
+
+        # Model Observers
+        self.monitors = {}
+
+        # VCA config
+        self.hostname = ""
+        self.port = 17070
+        self.username = ""
+        self.secret = ""
+
         if log:
             self.log = log
         else:
@@ -181,14 +213,22 @@ class N2VC:
 
         self.artifacts = artifacts
 
+        self.loop = loop or asyncio.get_event_loop()
+
     def __del__(self):
         """Close any open connections."""
         yield self.logout()
 
-    def notify_callback(self, model_name, application_name, status, callback=None, *callback_args):
+    def notify_callback(self, model_name, application_name, status, message,
+                        callback=None, *callback_args):
         try:
             if callback:
-                callback(model_name, application_name, status, *callback_args)
+                callback(
+                    model_name,
+                    application_name,
+                    status, message,
+                    *callback_args,
+                )
         except Exception as e:
             self.log.error("[0] notify_callback exception {}".format(e))
             raise e
@@ -214,15 +254,108 @@ class N2VC:
 
         return self.default_model
 
-    async def DeployCharms(self, model_name, application_name, vnfd, charm_path, params={}, machine_spec={}, callback=None, *callback_args):
+    async def Relate(self, ns_name, vnfd):
+        """Create a relation between the charm-enabled VDUs in a VNF.
+
+        The Relation mapping has two parts: the id of the vdu owning the endpoint, and the name of the endpoint.
+
+        vdu:
+            ...
+            relation:
+            -   provides: dataVM:db
+                requires: mgmtVM:app
+
+        This tells N2VC that the charm referred to by the dataVM vdu offers a relation named 'db', and the mgmtVM vdu has an 'app' endpoint that should be connected to a database.
+
+        :param str ns_name: The name of the network service.
+        :param dict vnfd: The parsed yaml VNF descriptor.
+        """
+
+        # Currently, the call to Relate() is made automatically after the
+        # deployment of each charm; if the relation depends on a charm that
+        # hasn't been deployed yet, the call will fail silently. This will
+        # prevent an API breakage, with the intent of making this an explicitly
+        # required call in a more object-oriented refactor of the N2VC API.
+
+        configs = []
+        vnf_config = vnfd.get("vnf-configuration")
+        if vnf_config:
+            juju = vnf_config['juju']
+            if juju:
+                configs.append(vnf_config)
+
+        for vdu in vnfd['vdu']:
+            vdu_config = vdu.get('vdu-configuration')
+            if vdu_config:
+                juju = vdu_config['juju']
+                if juju:
+                    configs.append(vdu_config)
+
+        def _get_application_name(name):
+            """Get the application name that's mapped to a vnf/vdu."""
+            vnf_member_index = 0
+            vnf_name = vnfd['name']
+
+            for vdu in vnfd.get('vdu'):
+                # Compare the named portion of the relation to the vdu's id
+                if vdu['id'] == name:
+                    application_name = self.FormatApplicationName(
+                        ns_name,
+                        vnf_name,
+                        str(vnf_member_index),
+                    )
+                    return application_name
+                else:
+                    vnf_member_index += 1
+
+            return None
+
+        # Loop through relations
+        for cfg in configs:
+            if 'juju' in cfg:
+                if 'relation' in juju:
+                    for rel in juju['relation']:
+                        try:
+
+                            # get the application name for the provides
+                            (name, endpoint) = rel['provides'].split(':')
+                            application_name = _get_application_name(name)
+
+                            provides = "{}:{}".format(
+                                application_name,
+                                endpoint
+                            )
+
+                            # get the application name for thr requires
+                            (name, endpoint) = rel['requires'].split(':')
+                            application_name = _get_application_name(name)
+
+                            requires = "{}:{}".format(
+                                application_name,
+                                endpoint
+                            )
+                            self.log.debug("Relation: {} <-> {}".format(
+                                provides,
+                                requires
+                            ))
+                            await self.add_relation(
+                                ns_name,
+                                provides,
+                                requires,
+                            )
+                        except Exception as e:
+                            self.log.debug("Exception: {}".format(e))
+
+        return
+
+    async def DeployCharms(self, model_name, application_name, vnfd,
+                           charm_path, params={}, machine_spec={},
+                           callback=None, *callback_args):
         """Deploy one or more charms associated with a VNF.
 
         Deploy the charm(s) referenced in a VNF Descriptor.
 
-        You can pass either the nsd record or the id of the network
-        service, but this method will fail without one of them.
-
-        :param str ns_name: The name of the network service
+        :param str model_name: The name of the network service.
         :param str application_name: The name of the application
         :param dict vnfd: The name of the application
         :param str charm_path: The path to the Juju charm
@@ -233,14 +366,16 @@ class N2VC:
             # Pass the initial-config-primitives section of the vnf or vdu
             'initial-config-primitives': {...}
           }
-        :param dict machine_spec: A dictionary describing the machine to install to
+        :param dict machine_spec: A dictionary describing the machine to
+        install to
           Examples::
           {
             'hostname': '1.2.3.4',
             'username': 'ubuntu',
           }
         :param obj callback: A callback function to receive status changes.
-        :param tuple callback_args: A list of arguments to be passed to the callback
+        :param tuple callback_args: A list of arguments to be passed to the
+        callback
         """
 
         ########################################################
@@ -248,7 +383,13 @@ class N2VC:
         ########################################################
         if not os.path.exists(charm_path):
             self.log.debug("Charm path doesn't exist: {}".format(charm_path))
-            self.notify_callback(model_name, application_name, "failed", callback, *callback_args)
+            self.notify_callback(
+                model_name,
+                application_name,
+                "failed",
+                callback,
+                *callback_args,
+            )
             raise JujuCharmNotFound("No artifacts configured.")
 
         ################################
@@ -271,29 +412,39 @@ class N2VC:
         ########################################
         app = await self.get_application(model, application_name)
         if app:
-            raise JujuApplicationExists("Can't deploy application \"{}\" to model \"{}\" because it already exists.".format(application_name, model))
+            raise JujuApplicationExists("Can't deploy application \"{}\" to model \"{}\" because it already exists.".format(application_name, model_name))
 
-        ############################################################
-        # Create a monitor to watch for application status changes #
-        ############################################################
+        ################################################################
+        # Register this application with the model-level event monitor #
+        ################################################################
         if callback:
-            self.log.debug("Setting monitor<->callback")
-            self.monitors[application_name] = VCAMonitor(model_name, application_name, callback, *callback_args)
-            model.add_observer(self.monitors[application_name])
+            self.monitors[model_name].AddApplication(
+                application_name,
+                callback,
+                *callback_args
+            )
 
         ########################################################
         # Check for specific machine placement (native charms) #
         ########################################################
         to = ""
         if machine_spec.keys():
-            # TODO: This needs to be tested.
-            # if all(k in machine_spec for k in ['hostname', 'username']):
-            #     # Enlist the existing machine in Juju
-            #     machine = await self.model.add_machine(spec='ssh:%@%'.format(
-            #         specs['host'],
-            #         specs['user'],
-            #     ))
-            #     to = machine.id
+            if all(k in machine_spec for k in ['hostname', 'username']):
+                # Get the path to the previously generated ssh private key.
+                # Machines we're manually provisioned must have N2VC's public
+                # key injected, so if we don't have a keypair, raise an error.
+                private_key_path = ""
+
+                # Enlist the existing machine in Juju
+                machine = await self.model.add_machine(
+                    spec='ssh:{}@{}:{}'.format(
+                        specs['host'],
+                        specs['user'],
+                        private_key_path,
+                    )
+                )
+                # Set the machine id that the deploy below will use.
+                to = machine.id
             pass
 
         #######################################
@@ -304,6 +455,9 @@ class N2VC:
         if 'rw_mgmt_ip' in params:
             rw_mgmt_ip = params['rw_mgmt_ip']
 
+        if 'initial-config-primitive' not in params:
+            params['initial-config-primitive'] = {}
+
         initial_config = self._get_config_from_dict(
             params['initial-config-primitive'],
             {'<rw_mgmt_ip>': rw_mgmt_ip}
@@ -329,55 +483,258 @@ class N2VC:
             series='xenial',
             # Apply the initial 'config' primitive during deployment
             config=initial_config,
-            # TBD: Where to deploy the charm to.
-            to=None,
+            # Where to deploy the charm to.
+            to=to,
         )
 
+        # Map the vdu id<->app name,
+        #
+        await self.Relate(model_name, vnfd)
+
         # #######################################
         # # Execute initial config primitive(s) #
         # #######################################
+        await self.ExecuteInitialPrimitives(
+            model_name,
+            application_name,
+            params,
+        )
+
+        # primitives = {}
+        #
+        # # Build a sequential list of the primitives to execute
+        # for primitive in params['initial-config-primitive']:
+        #     try:
+        #         if primitive['name'] == 'config':
+        #             # This is applied when the Application is deployed
+        #             pass
+        #         else:
+        #             seq = primitive['seq']
+        #
+        #             params = {}
+        #             if 'parameter' in primitive:
+        #                 params = primitive['parameter']
+        #
+        #             primitives[seq] = {
+        #                 'name': primitive['name'],
+        #                 'parameters': self._map_primitive_parameters(
+        #                     params,
+        #                     {'<rw_mgmt_ip>': rw_mgmt_ip}
+        #                 ),
+        #             }
+        #
+        #             for primitive in sorted(primitives):
+        #                 await self.ExecutePrimitive(
+        #                     model_name,
+        #                     application_name,
+        #                     primitives[primitive]['name'],
+        #                     callback,
+        #                     callback_args,
+        #                     **primitives[primitive]['parameters'],
+        #                 )
+        #     except N2VCPrimitiveExecutionFailed as e:
+        #         self.log.debug(
+        #             "[N2VC] Exception executing primitive: {}".format(e)
+        #         )
+        #         raise
+
+    async def GetPrimitiveStatus(self, model_name, uuid):
+        """Get the status of an executed Primitive.
+
+        The status of an executed Primitive will be one of three values:
+        - completed
+        - failed
+        - running
+        """
+        status = None
+        try:
+            if not self.authenticated:
+                await self.login()
+
+            # FIXME: This is hard-coded until model-per-ns is added
+            model_name = 'default'
+
+            model = await self.get_model(model_name)
+
+            results = await model.get_action_status(uuid)
+
+            if uuid in results:
+                status = results[uuid]
+
+        except Exception as e:
+            self.log.debug(
+                "Caught exception while getting primitive status: {}".format(e)
+            )
+            raise N2VCPrimitiveExecutionFailed(e)
+
+        return status
+
+    async def GetPrimitiveOutput(self, model_name, uuid):
+        """Get the output of an executed Primitive.
+
+        Note: this only returns output for a successfully executed primitive.
+        """
+        results = None
+        try:
+            if not self.authenticated:
+                await self.login()
+
+            # FIXME: This is hard-coded until model-per-ns is added
+            model_name = 'default'
+
+            model = await self.get_model(model_name)
+            results = await model.get_action_output(uuid, 60)
+        except Exception as e:
+            self.log.debug(
+                "Caught exception while getting primitive status: {}".format(e)
+            )
+            raise N2VCPrimitiveExecutionFailed(e)
+
+        return results
+
+    # async def ProvisionMachine(self, model_name, hostname, username):
+    #     """Provision machine for usage with Juju.
+    #
+    #     Provisions a previously instantiated machine for use with Juju.
+    #     """
+    #     try:
+    #         if not self.authenticated:
+    #             await self.login()
+    #
+    #         # FIXME: This is hard-coded until model-per-ns is added
+    #         model_name = 'default'
+    #
+    #         model = await self.get_model(model_name)
+    #         model.add_machine(spec={})
+    #
+    #         machine = await model.add_machine(spec='ssh:{}@{}:{}'.format(
+    #             "ubuntu",
+    #             host['address'],
+    #             private_key_path,
+    #         ))
+    #         return machine.id
+    #
+    #     except Exception as e:
+    #         self.log.debug(
+    #             "Caught exception while getting primitive status: {}".format(e)
+    #         )
+    #         raise N2VCPrimitiveExecutionFailed(e)
+
+    def GetPrivateKeyPath(self):
+        homedir = os.environ['HOME']
+        sshdir = "{}/.ssh".format(homedir)
+        private_key_path = "{}/id_n2vc_rsa".format(sshdir)
+        return private_key_path
+
+    async def GetPublicKey(self):
+        """Get the N2VC SSH public key.abs
+
+        Returns the SSH public key, to be injected into virtual machines to
+        be managed by the VCA.
+
+        The first time this is run, a ssh keypair will be created. The public
+        key is injected into a VM so that we can provision the machine with
+        Juju, after which Juju will communicate with the VM directly via the
+        juju agent.
+        """
+        public_key = ""
+
+        # Find the path to where we expect our key to live.
+        homedir = os.environ['HOME']
+        sshdir = "{}/.ssh".format(homedir)
+        if not os.path.exists(sshdir):
+            os.mkdir(sshdir)
+
+        private_key_path = "{}/id_n2vc_rsa".format(sshdir)
+        public_key_path = "{}.pub".format(private_key_path)
+
+        # If we don't have a key generated, generate it.
+        if not os.path.exists(private_key_path):
+            cmd = "ssh-keygen -t {} -b {} -N '' -f {}".format(
+                "rsa",
+                "4096",
+                private_key_path
+            )
+            subprocess.check_output(shlex.split(cmd))
+
+        # Read the public key
+        with open(public_key_path, "r") as f:
+            public_key = f.readline()
+
+        return public_key
+
+    async def ExecuteInitialPrimitives(self, model_name, application_name,
+                                       params, callback=None, *callback_args):
+        """Execute multiple primitives.
+
+        Execute multiple primitives as declared in initial-config-primitive.
+        This is useful in cases where the primitives initially failed -- for
+        example, if the charm is a proxy but the proxy hasn't been configured
+        yet.
+        """
+        uuids = []
         primitives = {}
 
         # Build a sequential list of the primitives to execute
         for primitive in params['initial-config-primitive']:
             try:
                 if primitive['name'] == 'config':
-                    # This is applied when the Application is deployed
                     pass
                 else:
-                    # TODO: We need to sort by seq, and queue the actions in order.
-
                     seq = primitive['seq']
 
+                    params = {}
+                    if 'parameter' in primitive:
+                        params = primitive['parameter']
+
                     primitives[seq] = {
                         'name': primitive['name'],
                         'parameters': self._map_primitive_parameters(
-                            primitive['parameter'],
-                            {'<rw_mgmt_ip>': rw_mgmt_ip}
+                            params,
+                            {'<rw_mgmt_ip>': None}
                         ),
                     }
 
                     for primitive in sorted(primitives):
-                        await self.ExecutePrimitive(
-                            model_name,
-                            application_name,
-                            primitives[primitive]['name'],
-                            callback,
-                            callback_args,
-                            **primitives[primitive]['parameters'],
+                        uuids.append(
+                            await self.ExecutePrimitive(
+                                model_name,
+                                application_name,
+                                primitives[primitive]['name'],
+                                callback,
+                                callback_args,
+                                **primitives[primitive]['parameters'],
+                            )
                         )
             except N2VCPrimitiveExecutionFailed as e:
-                self.debug.log(
+                self.log.debug(
                     "[N2VC] Exception executing primitive: {}".format(e)
                 )
                 raise
+        return uuids
 
-    async def ExecutePrimitive(self, model_name, application_name, primitive, callback, *callback_args, **params):
-        """
-        Queue the execution of a primitive
+    async def ExecutePrimitive(self, model_name, application_name, primitive,
+                               callback, *callback_args, **params):
+        """Execute a primitive of a charm for Day 1 or Day 2 configuration.
+
+        Execute a primitive defined in the VNF descriptor.
 
-        returns the UUID of the executed primitive
+        :param str model_name: The name of the network service.
+        :param str application_name: The name of the application
+        :param str primitive: The name of the primitive to execute.
+        :param obj callback: A callback function to receive status changes.
+        :param tuple callback_args: A list of arguments to be passed to the
+         callback function.
+        :param dict params: A dictionary of key=value pairs representing the
+         primitive's parameters
+          Examples::
+          {
+            'rw_mgmt_ip': '1.2.3.4',
+            # Pass the initial-config-primitives section of the vnf or vdu
+            'initial-config-primitives': {...}
+          }
         """
+        self.log.debug("Executing {}".format(primitive))
         uuid = None
         try:
             if not self.authenticated:
@@ -386,26 +743,42 @@ class N2VC:
             # FIXME: This is hard-coded until model-per-ns is added
             model_name = 'default'
 
+            model = await self.get_model(model_name)
+
             if primitive == 'config':
                 # config is special, and expecting params to be a dictionary
-                await self.set_config(application_name, params['params'])
+                await self.set_config(
+                    model,
+                    application_name,
+                    params['params'],
+                )
             else:
-                model = await self.controller.get_model(model_name)
                 app = await self.get_application(model, application_name)
                 if app:
                     # Run against the first (and probably only) unit in the app
                     unit = app.units[0]
                     if unit:
-                        self.log.debug("Executing primitive {}".format(primitive))
                         action = await unit.run_action(primitive, **params)
                         uuid = action.id
-                await model.disconnect()
         except Exception as e:
-            self.log.debug("Caught exception while executing primitive: {}".format(e))
-            raise e
+            self.log.debug(
+                "Caught exception while executing primitive: {}".format(e)
+            )
+            raise N2VCPrimitiveExecutionFailed(e)
         return uuid
 
-    async def RemoveCharms(self, model_name, application_name, callback=None, *callback_args):
+    async def RemoveCharms(self, model_name, application_name, callback=None,
+                           *callback_args):
+        """Remove a charm from the VCA.
+
+        Remove a charm referenced in a VNF Descriptor.
+
+        :param str model_name: The name of the network service.
+        :param str application_name: The name of the application
+        :param obj callback: A callback function to receive status changes.
+        :param tuple callback_args: A list of arguments to be passed to the
+         callback function.
+        """
         try:
             if not self.authenticated:
                 await self.login()
@@ -413,9 +786,24 @@ class N2VC:
             model = await self.get_model(model_name)
             app = await self.get_application(model, application_name)
             if app:
-                self.notify_callback(model_name, application_name, "removing", callback, *callback_args)
+                # Remove this application from event monitoring
+                self.monitors[model_name].RemoveApplication(application_name)
+
+                # self.notify_callback(model_name, application_name, "removing", callback, *callback_args)
+                self.log.debug(
+                    "Removing the application {}".format(application_name)
+                )
                 await app.remove()
-                self.notify_callback(model_name, application_name, "removed", callback, *callback_args)
+
+                # Notify the callback that this charm has been removed.
+                self.notify_callback(
+                    model_name,
+                    application_name,
+                    "removed",
+                    callback,
+                    *callback_args,
+                )
+
         except Exception as e:
             print("Caught exception: {}".format(e))
             self.log.debug(e)
@@ -424,35 +812,60 @@ class N2VC:
     async def DestroyNetworkService(self, nsd):
         raise NotImplementedError()
 
-    async def GetMetrics(self, nsd, vnfd):
-        """Get the metrics collected by the VCA."""
-        raise NotImplementedError()
+    async def GetMetrics(self, model_name, application_name):
+        """Get the metrics collected by the VCA.
+
+        :param model_name The name of the model
+        :param application_name The name of the application
+        """
+        metrics = {}
+        model = await self.get_model(model_name)
+        app = await self.get_application(model, application_name)
+        if app:
+            metrics = await app.get_metrics()
+
+        return metrics
+
+    async def HasApplication(self, model_name, application_name):
+        model = await self.get_model(model_name)
+        app = await self.get_application(model, application_name)
+        if app:
+            return True
+        return False
 
     # Non-public methods
-    async def add_relation(self, a, b, via=None):
+    async def add_relation(self, model_name, relation1, relation2):
         """
         Add a relation between two application endpoints.
 
-        :param a An application endpoint
-        :param b An application endpoint
-        :param via The egress subnet(s) for outbound traffic, e.g.,
-            (192.168.0.0/16,10.0.0.0/8)
+        :param str model_name Name of the network service.
+        :param str relation1 '<application>[:<relation_name>]'
+        :param str relation12 '<application>[:<relation_name>]'
         """
+
         if not self.authenticated:
             await self.login()
 
-        m = await self.get_model()
+        m = await self.get_model(model_name)
         try:
-            m.add_relation(a, b, via)
-        finally:
-            await m.disconnect()
+            await m.add_relation(relation1, relation2)
+        except JujuAPIError as e:
+            # If one of the applications in the relationship doesn't exist,
+            # or the relation has already been added, let the operation fail
+            # silently.
+            if 'not found' in e.message:
+                return
+            if 'already exists' in e.message:
+                return
 
-    async def apply_config(self, config, application):
-        """Apply a configuration to the application."""
-        print("JujuApi: Applying configuration to {}.".format(
-            application
-        ))
-        return await self.set_config(application=application, config=config)
+            raise e
+
+    # async def apply_config(self, config, application):
+    #     """Apply a configuration to the application."""
+    #     print("JujuApi: Applying configuration to {}.".format(
+    #         application
+    #     ))
+    #     return await self.set_config(application=application, config=config)
 
     def _get_config_from_dict(self, config_primitive, values):
         """Transform the yang config primitive to dict.
@@ -480,10 +893,23 @@ class N2VC:
         params = {}
         for parameter in parameters:
             param = str(parameter['name'])
+
+            # Typecast parameter value, if present
+            if 'data-type' in parameter:
+                paramtype = str(parameter['data-type']).lower()
+                value = None
+
+                if paramtype == "integer":
+                    value = int(parameter['value'])
+                elif paramtype == "boolean":
+                    value = bool(parameter['value'])
+                else:
+                    value = str(parameter['value'])
+
             if parameter['value'] == "<rw_mgmt_ip>":
                 params[param] = str(values[parameter['value']])
             else:
-                params[param] = str(parameter['value'])
+                params[param] = value
         return params
 
     def _get_config_from_yang(self, config_primitive, values):
@@ -500,6 +926,7 @@ class N2VC:
 
         return config
 
+    @staticmethod
     def FormatApplicationName(self, *args):
         """
         Generate a Juju-compatible Application name
@@ -525,7 +952,6 @@ class N2VC:
             appname += c
         return re.sub('\-+', '-', appname.lower())
 
-
     # def format_application_name(self, nsd_name, vnfr_name, member_vnf_index=0):
     #     """Format the name of the application
     #
@@ -573,8 +999,14 @@ class N2VC:
             await self.login()
 
         if model_name not in self.models:
-            print("connecting to model {}".format(model_name))
-            self.models[model_name] = await self.controller.get_model(model_name)
+            self.models[model_name] = await self.controller.get_model(
+                model_name,
+            )
+            self.refcount['model'] += 1
+
+            # Create an observer for this model
+            self.monitors[model_name] = VCAMonitor(model_name)
+            self.models[model_name].add_observer(self.monitors[model_name])
 
         return self.models[model_name]
 
@@ -589,16 +1021,24 @@ class N2VC:
         self.log.debug("JujuApi: Logging into controller")
 
         cacert = None
-        self.controller = Controller()
+        self.controller = Controller(loop=self.loop)
 
         if self.secret:
-            self.log.debug("Connecting to controller... ws://{}:{} as {}/{}".format(self.endpoint, self.port, self.user, self.secret))
+            self.log.debug(
+                "Connecting to controller... ws://{}:{} as {}/{}".format(
+                    self.endpoint,
+                    self.port,
+                    self.user,
+                    self.secret,
+                )
+            )
             await self.controller.connect(
                 endpoint=self.endpoint,
                 username=self.user,
                 password=self.secret,
                 cacert=cacert,
             )
+            self.refcount['controller'] += 1
         else:
             # current_controller no longer exists
             # self.log.debug("Connecting to current controller...")
@@ -613,8 +1053,6 @@ class N2VC:
         self.authenticated = True
         self.log.debug("JujuApi: Logged into controller")
 
-        # self.default_model = await self.controller.get_model("default")
-
     async def logout(self):
         """Logout of the Juju controller."""
         if not self.authenticated:
@@ -622,24 +1060,36 @@ class N2VC:
 
         try:
             if self.default_model:
-                self.log.debug("Disconnecting model {}".format(self.default_model))
+                self.log.debug("Disconnecting model {}".format(
+                    self.default_model
+                ))
                 await self.default_model.disconnect()
+                self.refcount['model'] -= 1
                 self.default_model = None
 
             for model in self.models:
                 await self.models[model].disconnect()
+                self.refcount['model'] -= 1
+                self.models[model] = None
 
             if self.controller:
-                self.log.debug("Disconnecting controller {}".format(self.controller))
+                self.log.debug("Disconnecting controller {}".format(
+                    self.controller
+                ))
                 await self.controller.disconnect()
-                # self.controller = None
+                self.refcount['controller'] -= 1
+                self.controller = None
 
             self.authenticated = False
+
+            self.log.debug(self.refcount)
+
         except Exception as e:
-            self.log.fail("Fatal error logging out of Juju Controller: {}".format(e))
+            self.log.fatal(
+                "Fatal error logging out of Juju Controller: {}".format(e)
+            )
             raise e
 
-
     # async def remove_application(self, name):
     #     """Remove the application."""
     #     if not self.authenticated:
@@ -676,9 +1126,11 @@ class N2VC:
 
         app = await self.get_application(self.default_model, application)
         if app:
-            self.log.debug("JujuApi: Resolving errors for application {}".format(
-                application,
-            ))
+            self.log.debug(
+                "JujuApi: Resolving errors for application {}".format(
+                    application,
+                )
+            )
 
             for unit in app.units:
                 app.resolved(retry=True)
@@ -700,10 +1152,12 @@ class N2VC:
             # so use the first unit available.
             unit = app.units[0]
 
-            self.log.debug("JujuApi: Running Action {} against Application {}".format(
-                action_name,
-                application,
-            ))
+            self.log.debug(
+                "JujuApi: Running Action {} against Application {}".format(
+                    action_name,
+                    application,
+                )
+            )
 
             action = await unit.run_action(action_name, **params)
 
@@ -716,12 +1170,12 @@ class N2VC:
 
         return result
 
-    async def set_config(self, application, config):
+    async def set_config(self, model_name, application, config):
         """Apply a configuration to the application."""
         if not self.authenticated:
             await self.login()
 
-        app = await self.get_application(self.default_model, application)
+        app = await self.get_application(model_name, application)
         if app:
             self.log.debug("JujuApi: Setting config for Application {}".format(
                 application,
@@ -734,40 +1188,47 @@ class N2VC:
                 if config[key] != newconf[key]['value']:
                     self.log.debug("JujuApi: Config not set! Key {} Value {} doesn't match {}".format(key, config[key], newconf[key]))
 
-    async def set_parameter(self, parameter, value, application=None):
-        """Set a config parameter for a service."""
-        if not self.authenticated:
-            await self.login()
-
-        self.log.debug("JujuApi: Setting {}={} for Application {}".format(
-            parameter,
-            value,
-            application,
-        ))
-        return await self.apply_config(
-            {parameter: value},
-            application=application,
-        )
-
-    async def wait_for_application(self, name, timeout=300):
+    # async def set_parameter(self, parameter, value, application=None):
+    #     """Set a config parameter for a service."""
+    #     if not self.authenticated:
+    #         await self.login()
+    #
+    #     self.log.debug("JujuApi: Setting {}={} for Application {}".format(
+    #         parameter,
+    #         value,
+    #         application,
+    #     ))
+    #     return await self.apply_config(
+    #         {parameter: value},
+    #         application=application,
+        # )
+
+    async def wait_for_application(self, model_name, application_name,
+                                   timeout=300):
         """Wait for an application to become active."""
         if not self.authenticated:
             await self.login()
 
-        app = await self.get_application(self.default_model, name)
+        # TODO: In a point release, we will use a model per deployed network
+        # service. In the meantime, we will always use the 'default' model.
+        model_name = 'default'
+        model = await self.get_model(model_name)
+
+        app = await self.get_application(model, application_name)
+        self.log.debug("Application: {}".format(app))
+        # app = await self.get_application(model_name, application_name)
         if app:
             self.log.debug(
                 "JujuApi: Waiting {} seconds for Application {}".format(
                     timeout,
-                    name,
+                    application_name,
                 )
             )
 
-            await self.default_model.block_until(
+            await model.block_until(
                 lambda: all(
-                    unit.agent_status == 'idle'
-                    and unit.workload_status
-                    in ['active', 'unknown'] for unit in app.units
+                    unit.agent_status == 'idle' and unit.workload_status in
+                    ['active', 'unknown'] for unit in app.units
                 ),
                 timeout=timeout
             )