Fix bug 1533: use bionic as default series in proxy charms
[osm/N2VC.git] / n2vc / n2vc_juju_conn.py
index bac0f2c..eed2f30 100644 (file)
 # contact with: nfvlabs@tid.es
 ##
 
-import logging
-import os
 import asyncio
-import time
-import base64
-import binascii
-import re
+import logging
 
+from n2vc.config import EnvironConfig
+from n2vc.exceptions import (
+    N2VCBadArgumentsException,
+    N2VCException,
+    N2VCConnectionException,
+    N2VCExecutionException,
+    # N2VCNotFound,
+    MethodNotImplemented,
+)
 from n2vc.n2vc_conn import N2VCConnector
 from n2vc.n2vc_conn import obj_to_dict, obj_to_yaml
-from n2vc.exceptions \
-    import N2VCBadArgumentsException, N2VCException, N2VCConnectionException, \
-    N2VCExecutionException, N2VCInvalidCertificate, N2VCNotFound
-from n2vc.juju_observer import JujuModelObserver
-
-from juju.controller import Controller
-from juju.model import Model
-from juju.application import Application
-from juju.action import Action
-from juju.machine import Machine
-from juju.client import client
-from juju.errors import JujuAPIError
-
-from n2vc.provisioner import SSHProvisioner
+from n2vc.libjuju import Libjuju
+from n2vc.store import MotorStore
+from n2vc.vca.connection import get_connection
 
 
 class N2VCJujuConnector(N2VCConnector):
 
     """
-    ##################################################################################################
-    ########################################## P U B L I C ###########################################
-    ##################################################################################################
+    ####################################################################################
+    ################################### P U B L I C ####################################
+    ####################################################################################
     """
 
+    BUILT_IN_CLOUDS = ["localhost", "microk8s"]
+    libjuju = None
+
     def __init__(
         self,
         db: object,
         fs: object,
         log: object = None,
         loop: object = None,
-        url: str = '127.0.0.1:17070',
-        username: str = 'admin',
-        vca_config: dict = None,
-        on_update_db=None
+        on_update_db=None,
     ):
-        """Initialize juju N2VC connector
+        """
+        Constructor
+
+        :param: db: Database object from osm_common
+        :param: fs: Filesystem object from osm_common
+        :param: log: Logger
+        :param: loop: Asyncio loop
+        :param: on_update_db: Callback function to be called for updating the database.
         """
 
         # parent class constructor
@@ -75,195 +75,190 @@ class N2VCJujuConnector(N2VCConnector):
             fs=fs,
             log=log,
             loop=loop,
-            url=url,
-            username=username,
-            vca_config=vca_config,
-            on_update_db=on_update_db
+            on_update_db=on_update_db,
         )
 
         # silence websocket traffic log
-        logging.getLogger('websockets.protocol').setLevel(logging.INFO)
-        logging.getLogger('juju.client.connection').setLevel(logging.WARN)
-        logging.getLogger('model').setLevel(logging.WARN)
-
-        self.log.info('Initializing N2VC juju connector...')
-
-        """
-        ##############################################################
-        # check arguments
-        ##############################################################
-        """
-
-        # juju URL
-        if url is None:
-            raise N2VCBadArgumentsException('Argument url is mandatory', ['url'])
-        url_parts = url.split(':')
-        if len(url_parts) != 2:
-            raise N2VCBadArgumentsException('Argument url: bad format (localhost:port) -> {}'.format(url), ['url'])
-        self.hostname = url_parts[0]
-        try:
-            self.port = int(url_parts[1])
-        except ValueError:
-            raise N2VCBadArgumentsException('url port must be a number -> {}'.format(url), ['url'])
+        logging.getLogger("websockets.protocol").setLevel(logging.INFO)
+        logging.getLogger("juju.client.connection").setLevel(logging.WARN)
+        logging.getLogger("model").setLevel(logging.WARN)
 
-        # juju USERNAME
-        if username is None:
-            raise N2VCBadArgumentsException('Argument username is mandatory', ['username'])
+        self.log.info("Initializing N2VC juju connector...")
 
-        # juju CONFIGURATION
-        if vca_config is None:
-            raise N2VCBadArgumentsException('Argument vca_config is mandatory', ['vca_config'])
+        db_uri = EnvironConfig(prefixes=["OSMLCM_", "OSMMON_"]).get("database_uri")
+        self._store = MotorStore(db_uri)
+        self.loading_libjuju = asyncio.Lock(loop=self.loop)
 
-        if 'secret' in vca_config:
-            self.secret = vca_config['secret']
-        else:
-            raise N2VCBadArgumentsException('Argument vca_config.secret is mandatory', ['vca_config.secret'])
-
-        # pubkey of juju client in osm machine: ~/.local/share/juju/ssh/juju_id_rsa.pub
-        # if exists, it will be written in lcm container: _create_juju_public_key()
-        if 'public_key' in vca_config:
-            self.public_key = vca_config['public_key']
-        else:
-            self.public_key = None
-
-        # TODO: Verify ca_cert is valid before using. VCA will crash
-        # if the ca_cert isn't formatted correctly.
-        def base64_to_cacert(b64string):
-            """Convert the base64-encoded string containing the VCA CACERT.
-
-            The input string....
-
-            """
-            try:
-                cacert = base64.b64decode(b64string).decode("utf-8")
+        self.log.info("N2VC juju connector initialized")
 
-                cacert = re.sub(
-                    r'\\n',
-                    r'\n',
-                    cacert,
-                )
-            except binascii.Error as e:
-                self.log.debug("Caught binascii.Error: {}".format(e))
-                raise N2VCInvalidCertificate(message="Invalid CA Certificate")
-
-            return cacert
-
-        self.ca_cert = vca_config.get('ca_cert')
-        if self.ca_cert:
-            self.ca_cert = base64_to_cacert(vca_config['ca_cert'])
-
-        if 'api_proxy' in vca_config:
-            self.api_proxy = vca_config['api_proxy']
-            self.log.debug('api_proxy for native charms configured: {}'.format(self.api_proxy))
-        else:
-            self.warning('api_proxy is not configured. Support for native charms is disabled')
-
-        if 'enable_os_upgrade' in vca_config:
-            self.enable_os_upgrade = vca_config['enable_os_upgrade']
-        else:
-            self.enable_os_upgrade = True
-
-        if 'apt_mirror' in vca_config:
-            self.apt_mirror = vca_config['apt_mirror']
-        else:
-            self.apt_mirror = None
-
-        self.cloud = vca_config.get('cloud')
-        self.log.debug('Arguments have been checked')
-
-        # juju data
-        self.controller = None         # it will be filled when connect to juju
-        self.juju_models = {}          # model objects for every model_name
-        self.juju_observers = {}       # model observers for every model_name
-        self._connecting = False       # while connecting to juju (to avoid duplicate connections)
-        self._authenticated = False    # it will be True when juju connection be stablished
-        self._creating_model = False   # True during model creation
-
-        # create juju pub key file in lcm container at ./local/share/juju/ssh/juju_id_rsa.pub
-        self._create_juju_public_key()
-
-        self.log.info('N2VC juju connector initialized')
+    async def get_status(
+        self, namespace: str, yaml_format: bool = True, vca_id: str = None
+    ):
+        """
+        Get status from all juju models from a VCA
 
-    async def get_status(self, namespace: str, yaml_format: bool = True):
+        :param namespace: we obtain ns from namespace
+        :param yaml_format: returns a yaml string
+        :param: vca_id: VCA ID from which the status will be retrieved.
+        """
+        # TODO: Review where is this function used. It is not optimal at all to get the status
+        #       from all the juju models of a particular VCA. Additionally, these models might
+        #       not have been deployed by OSM, in that case we are getting information from
+        #       deployments outside of OSM's scope.
 
         # self.log.info('Getting NS status. namespace: {}'.format(namespace))
+        libjuju = await self._get_libjuju(vca_id)
 
-        if not self._authenticated:
-            await self._juju_login()
-
-        nsi_id, ns_id, vnf_id, vdu_id, vdu_count = self._get_namespace_components(namespace=namespace)
+        _nsi_id, ns_id, _vnf_id, _vdu_id, _vdu_count = self._get_namespace_components(
+            namespace=namespace
+        )
         # model name is ns_id
         model_name = ns_id
         if model_name is None:
-            msg = 'Namespace {} not valid'.format(namespace)
+            msg = "Namespace {} not valid".format(namespace)
             self.log.error(msg)
-            raise N2VCBadArgumentsException(msg, ['namespace'])
+            raise N2VCBadArgumentsException(msg, ["namespace"])
 
-        # get juju model (create model if needed)
-        model = await self._juju_get_model(model_name=model_name)
+        status = {}
+        models = await libjuju.list_models(contains=ns_id)
 
-        status = await model.get_status()
+        for m in models:
+            status[m] = await libjuju.get_model_status(m)
 
         if yaml_format:
             return obj_to_yaml(status)
         else:
             return obj_to_dict(status)
 
+    async def update_vca_status(self, vcastatus: dict, vca_id: str = None):
+        """
+        Add all configs, actions, executed actions of all applications in a model to vcastatus dict.
+
+        :param vcastatus: dict containing vcaStatus
+        :param: vca_id: VCA ID
+
+        :return: None
+        """
+        try:
+            libjuju = await self._get_libjuju(vca_id)
+            for model_name in vcastatus:
+                # Adding executed actions
+                vcastatus[model_name][
+                    "executedActions"
+                ] = await libjuju.get_executed_actions(model_name)
+                for application in vcastatus[model_name]["applications"]:
+                    # Adding application actions
+                    vcastatus[model_name]["applications"][application][
+                        "actions"
+                    ] = await libjuju.get_actions(application, model_name)
+                    # Adding application configs
+                    vcastatus[model_name]["applications"][application][
+                        "configs"
+                    ] = await libjuju.get_application_configs(model_name, application)
+        except Exception as e:
+            self.log.debug("Error in updating vca status: {}".format(str(e)))
+
     async def create_execution_environment(
         self,
         namespace: str,
         db_dict: dict,
         reuse_ee_id: str = None,
         progress_timeout: float = None,
-        total_timeout: float = None
+        total_timeout: float = None,
+        vca_id: str = None,
     ) -> (str, dict):
+        """
+        Create an Execution Environment. Returns when it is created or raises an
+        exception on failing
+
+        :param: namespace: Contains a dot separate string.
+                    LCM will use: [<nsi-id>].<ns-id>.<vnf-id>.<vdu-id>[-<count>]
+        :param: db_dict: where to write to database when the status changes.
+            It contains a dictionary with {collection: str, filter: {},  path: str},
+                e.g. {collection: "nsrs", filter: {_id: <nsd-id>, path:
+                "_admin.deployed.VCA.3"}
+        :param: reuse_ee_id: ee id from an older execution. It allows us to reuse an
+                             older environment
+        :param: progress_timeout: Progress timeout
+        :param: total_timeout: Total timeout
+        :param: vca_id: VCA ID
+
+        :returns: id of the new execution environment and credentials for it
+                  (credentials can contains hostname, username, etc depending on underlying cloud)
+        """
 
-        self.log.info('Creating execution environment. namespace: {}, reuse_ee_id: {}'.format(namespace, reuse_ee_id))
-
-        if not self._authenticated:
-            await self._juju_login()
+        self.log.info(
+            "Creating execution environment. namespace: {}, reuse_ee_id: {}".format(
+                namespace, reuse_ee_id
+            )
+        )
+        libjuju = await self._get_libjuju(vca_id)
 
         machine_id = None
         if reuse_ee_id:
-            model_name, application_name, machine_id = self._get_ee_id_components(ee_id=reuse_ee_id)
+            model_name, application_name, machine_id = self._get_ee_id_components(
+                ee_id=reuse_ee_id
+            )
         else:
-            nsi_id, ns_id, vnf_id, vdu_id, vdu_count = self._get_namespace_components(namespace=namespace)
+            (
+                _nsi_id,
+                ns_id,
+                _vnf_id,
+                _vdu_id,
+                _vdu_count,
+            ) = self._get_namespace_components(namespace=namespace)
             # model name is ns_id
             model_name = ns_id
             # application name
             application_name = self._get_application_name(namespace=namespace)
 
-        self.log.debug('model name: {}, application name:  {}, machine_id: {}'
-                   .format(model_name, application_name, machine_id))
+        self.log.debug(
+            "model name: {}, application name:  {}, machine_id: {}".format(
+                model_name, application_name, machine_id
+            )
+        )
 
         # create or reuse a new juju machine
         try:
-            machine = await self._juju_create_machine(
+            if not await libjuju.model_exists(model_name):
+                await libjuju.add_model(
+                    model_name,
+                    libjuju.vca_connection.lxd_cloud,
+                )
+            machine, new = await libjuju.create_machine(
                 model_name=model_name,
-                application_name=application_name,
                 machine_id=machine_id,
                 db_dict=db_dict,
                 progress_timeout=progress_timeout,
-                total_timeout=total_timeout
+                total_timeout=total_timeout,
+            )
+            # id for the execution environment
+            ee_id = N2VCJujuConnector._build_ee_id(
+                model_name=model_name,
+                application_name=application_name,
+                machine_id=str(machine.entity_id),
             )
+            self.log.debug("ee_id: {}".format(ee_id))
+
+            if new:
+                # write ee_id in database
+                self._write_ee_id_db(db_dict=db_dict, ee_id=ee_id)
+
         except Exception as e:
-            message = 'Error creating machine on juju: {}'.format(e)
+            message = "Error creating machine on juju: {}".format(e)
             self.log.error(message)
             raise N2VCException(message=message)
 
-        # id for the execution environment
-        ee_id = N2VCJujuConnector._build_ee_id(
-            model_name=model_name,
-            application_name=application_name,
-            machine_id=str(machine.entity_id)
-        )
-        self.log.debug('ee_id: {}'.format(ee_id))
-
         # new machine credentials
-        credentials = dict()
-        credentials['hostname'] = machine.dns_name
+        credentials = {
+            "hostname": machine.dns_name,
+        }
 
-        self.log.info('Execution environment created. ee_id: {}, credentials: {}'.format(ee_id, credentials))
+        self.log.info(
+            "Execution environment created. ee_id: {}, credentials: {}".format(
+                ee_id, credentials
+            )
+        )
 
         return ee_id, credentials
 
@@ -273,31 +268,61 @@ class N2VCJujuConnector(N2VCConnector):
         credentials: dict,
         db_dict: dict,
         progress_timeout: float = None,
-        total_timeout: float = None
+        total_timeout: float = None,
+        vca_id: str = None,
     ) -> str:
-
-        if not self._authenticated:
-            await self._juju_login()
-
-        self.log.info('Registering execution environment. namespace={}, credentials={}'.format(namespace, credentials))
+        """
+        Register an existing execution environment at the VCA
+
+        :param: namespace: Contains a dot separate string.
+                    LCM will use: [<nsi-id>].<ns-id>.<vnf-id>.<vdu-id>[-<count>]
+        :param: credentials: credentials to access the existing execution environment
+                            (it can contains hostname, username, path to private key,
+                            etc depending on underlying cloud)
+        :param: db_dict: where to write to database when the status changes.
+            It contains a dictionary with {collection: str, filter: {},  path: str},
+                e.g. {collection: "nsrs", filter: {_id: <nsd-id>, path:
+                "_admin.deployed.VCA.3"}
+        :param: reuse_ee_id: ee id from an older execution. It allows us to reuse an
+                             older environment
+        :param: progress_timeout: Progress timeout
+        :param: total_timeout: Total timeout
+        :param: vca_id: VCA ID
+
+        :returns: id of the execution environment
+        """
+        self.log.info(
+            "Registering execution environment. namespace={}, credentials={}".format(
+                namespace, credentials
+            )
+        )
+        libjuju = await self._get_libjuju(vca_id)
 
         if credentials is None:
-            raise N2VCBadArgumentsException(message='credentials are mandatory', bad_args=['credentials'])
-        if credentials.get('hostname'):
-            hostname = credentials['hostname']
+            raise N2VCBadArgumentsException(
+                message="credentials are mandatory", bad_args=["credentials"]
+            )
+        if credentials.get("hostname"):
+            hostname = credentials["hostname"]
         else:
-            raise N2VCBadArgumentsException(message='hostname is mandatory', bad_args=['credentials.hostname'])
-        if credentials.get('username'):
-            username = credentials['username']
+            raise N2VCBadArgumentsException(
+                message="hostname is mandatory", bad_args=["credentials.hostname"]
+            )
+        if credentials.get("username"):
+            username = credentials["username"]
         else:
-            raise N2VCBadArgumentsException(message='username is mandatory', bad_args=['credentials.username'])
-        if 'private_key_path' in credentials:
-            private_key_path = credentials['private_key_path']
+            raise N2VCBadArgumentsException(
+                message="username is mandatory", bad_args=["credentials.username"]
+            )
+        if "private_key_path" in credentials:
+            private_key_path = credentials["private_key_path"]
         else:
             # if not passed as argument, use generated private key path
             private_key_path = self.private_key_path
 
-        nsi_id, ns_id, vnf_id, vdu_id, vdu_count = self._get_namespace_components(namespace=namespace)
+        _nsi_id, ns_id, _vnf_id, _vdu_id, _vdu_count = self._get_namespace_components(
+            namespace=namespace
+        )
 
         # model name
         model_name = ns_id
@@ -306,29 +331,36 @@ class N2VCJujuConnector(N2VCConnector):
 
         # register machine on juju
         try:
-            machine_id = await self._juju_provision_machine(
+            if not await libjuju.model_exists(model_name):
+                await libjuju.add_model(
+                    model_name,
+                    libjuju.vca_connection.lxd_cloud,
+                )
+            machine_id = await libjuju.provision_machine(
                 model_name=model_name,
                 hostname=hostname,
                 username=username,
                 private_key_path=private_key_path,
                 db_dict=db_dict,
                 progress_timeout=progress_timeout,
-                total_timeout=total_timeout
+                total_timeout=total_timeout,
             )
         except Exception as e:
-            self.log.error('Error registering machine: {}'.format(e))
-            raise N2VCException(message='Error registering machine on juju: {}'.format(e))
+            self.log.error("Error registering machine: {}".format(e))
+            raise N2VCException(
+                message="Error registering machine on juju: {}".format(e)
+            )
 
-        self.log.info('Machine registered: {}'.format(machine_id))
+        self.log.info("Machine registered: {}".format(machine_id))
 
         # id for the execution environment
         ee_id = N2VCJujuConnector._build_ee_id(
             model_name=model_name,
             application_name=application_name,
-            machine_id=str(machine_id)
+            machine_id=str(machine_id),
         )
 
-        self.log.info('Execution environment registered. ee_id: {}'.format(ee_id))
+        self.log.info("Execution environment registered. ee_id: {}".format(ee_id))
 
         return ee_id
 
@@ -340,87 +372,262 @@ class N2VCJujuConnector(N2VCConnector):
         progress_timeout: float = None,
         total_timeout: float = None,
         config: dict = None,
+        num_units: int = 1,
+        vca_id: str = None,
     ):
+        """
+        Install the software inside the execution environment identified by ee_id
+
+        :param: ee_id: the id of the execution environment returned by
+                          create_execution_environment or register_execution_environment
+        :param: artifact_path: where to locate the artifacts (parent folder) using
+                                  the self.fs
+                                  the final artifact path will be a combination of this
+                                  artifact_path and additional string from the config_dict
+                                  (e.g. charm name)
+        :param: db_dict: where to write into database when the status changes.
+                             It contains a dict with
+                                {collection: <str>, filter: {},  path: <str>},
+                                e.g. {collection: "nsrs", filter:
+                                    {_id: <nsd-id>, path: "_admin.deployed.VCA.3"}
+        :param: progress_timeout: Progress timeout
+        :param: total_timeout: Total timeout
+        :param: config: Dictionary with deployment config information.
+        :param: num_units: Number of units to deploy of a particular charm.
+        :param: vca_id: VCA ID
+        """
 
-        self.log.info('Installing configuration sw on ee_id: {}, artifact path: {}, db_dict: {}'
-                  .format(ee_id, artifact_path, db_dict))
-
-        if not self._authenticated:
-            await self._juju_login()
+        self.log.info(
+            (
+                "Installing configuration sw on ee_id: {}, "
+                "artifact path: {}, db_dict: {}"
+            ).format(ee_id, artifact_path, db_dict)
+        )
+        libjuju = await self._get_libjuju(vca_id)
 
         # check arguments
         if ee_id is None or len(ee_id) == 0:
-            raise N2VCBadArgumentsException(message='ee_id is mandatory', bad_args=['ee_id'])
+            raise N2VCBadArgumentsException(
+                message="ee_id is mandatory", bad_args=["ee_id"]
+            )
         if artifact_path is None or len(artifact_path) == 0:
-            raise N2VCBadArgumentsException(message='artifact_path is mandatory', bad_args=['artifact_path'])
+            raise N2VCBadArgumentsException(
+                message="artifact_path is mandatory", bad_args=["artifact_path"]
+            )
         if db_dict is None:
-            raise N2VCBadArgumentsException(message='db_dict is mandatory', bad_args=['db_dict'])
+            raise N2VCBadArgumentsException(
+                message="db_dict is mandatory", bad_args=["db_dict"]
+            )
 
         try:
-            model_name, application_name, machine_id = N2VCJujuConnector._get_ee_id_components(ee_id=ee_id)
-            self.log.debug('model: {}, application: {}, machine: {}'.format(model_name, application_name, machine_id))
-        except Exception as e:
+            (
+                model_name,
+                application_name,
+                machine_id,
+            ) = N2VCJujuConnector._get_ee_id_components(ee_id=ee_id)
+            self.log.debug(
+                "model: {}, application: {}, machine: {}".format(
+                    model_name, application_name, machine_id
+                )
+            )
+        except Exception:
             raise N2VCBadArgumentsException(
-                message='ee_id={} is not a valid execution environment id'.format(ee_id),
-                bad_args=['ee_id']
+                message="ee_id={} is not a valid execution environment id".format(
+                    ee_id
+                ),
+                bad_args=["ee_id"],
             )
 
         # remove // in charm path
-        while artifact_path.find('//') >= 0:
-            artifact_path = artifact_path.replace('//', '/')
+        while artifact_path.find("//") >= 0:
+            artifact_path = artifact_path.replace("//", "/")
 
         # check charm path
         if not self.fs.file_exists(artifact_path, mode="dir"):
-            msg = 'artifact path does not exist: {}'.format(artifact_path)
-            raise N2VCBadArgumentsException(message=msg, bad_args=['artifact_path'])
+            msg = "artifact path does not exist: {}".format(artifact_path)
+            raise N2VCBadArgumentsException(message=msg, bad_args=["artifact_path"])
 
-        if artifact_path.startswith('/'):
+        if artifact_path.startswith("/"):
             full_path = self.fs.path + artifact_path
         else:
-            full_path = self.fs.path + '/' + artifact_path
+            full_path = self.fs.path + "/" + artifact_path
 
         try:
-            application, retries = await self._juju_deploy_charm(
+            await libjuju.deploy_charm(
                 model_name=model_name,
                 application_name=application_name,
-                charm_path=full_path,
+                path=full_path,
                 machine_id=machine_id,
                 db_dict=db_dict,
                 progress_timeout=progress_timeout,
                 total_timeout=total_timeout,
-                config=config
+                config=config,
+                num_units=num_units,
+            )
+        except Exception as e:
+            raise N2VCException(
+                message="Error desploying charm into ee={} : {}".format(ee_id, e)
+            )
+
+        self.log.info("Configuration sw installed")
+
+    async def install_k8s_proxy_charm(
+        self,
+        charm_name: str,
+        namespace: str,
+        artifact_path: str,
+        db_dict: dict,
+        progress_timeout: float = None,
+        total_timeout: float = None,
+        config: dict = None,
+        vca_id: str = None,
+    ) -> str:
+        """
+        Install a k8s proxy charm
+
+        :param charm_name: Name of the charm being deployed
+        :param namespace: collection of all the uuids related to the charm.
+        :param str artifact_path: where to locate the artifacts (parent folder) using
+            the self.fs
+            the final artifact path will be a combination of this artifact_path and
+            additional string from the config_dict (e.g. charm name)
+        :param dict db_dict: where to write into database when the status changes.
+                        It contains a dict with
+                            {collection: <str>, filter: {},  path: <str>},
+                            e.g. {collection: "nsrs", filter:
+                                {_id: <nsd-id>, path: "_admin.deployed.VCA.3"}
+        :param: progress_timeout: Progress timeout
+        :param: total_timeout: Total timeout
+        :param config: Dictionary with additional configuration
+        :param vca_id: VCA ID
+
+        :returns ee_id: execution environment id.
+        """
+        self.log.info(
+            "Installing k8s proxy charm: {}, artifact path: {}, db_dict: {}".format(
+                charm_name, artifact_path, db_dict
+            )
+        )
+        libjuju = await self._get_libjuju(vca_id)
+
+        if artifact_path is None or len(artifact_path) == 0:
+            raise N2VCBadArgumentsException(
+                message="artifact_path is mandatory", bad_args=["artifact_path"]
+            )
+        if db_dict is None:
+            raise N2VCBadArgumentsException(
+                message="db_dict is mandatory", bad_args=["db_dict"]
+            )
+
+        # remove // in charm path
+        while artifact_path.find("//") >= 0:
+            artifact_path = artifact_path.replace("//", "/")
+
+        # check charm path
+        if not self.fs.file_exists(artifact_path, mode="dir"):
+            msg = "artifact path does not exist: {}".format(artifact_path)
+            raise N2VCBadArgumentsException(message=msg, bad_args=["artifact_path"])
+
+        if artifact_path.startswith("/"):
+            full_path = self.fs.path + artifact_path
+        else:
+            full_path = self.fs.path + "/" + artifact_path
+
+        _, ns_id, _, _, _ = self._get_namespace_components(namespace=namespace)
+        model_name = "{}-k8s".format(ns_id)
+        if not await libjuju.model_exists(model_name):
+            await libjuju.add_model(
+                model_name,
+                libjuju.vca_connection.k8s_cloud,
+            )
+        application_name = self._get_application_name(namespace)
+
+        try:
+            await libjuju.deploy_charm(
+                model_name=model_name,
+                application_name=application_name,
+                path=full_path,
+                machine_id=None,
+                db_dict=db_dict,
+                progress_timeout=progress_timeout,
+                total_timeout=total_timeout,
+                config=config,
             )
         except Exception as e:
-            raise N2VCException(message='Error desploying charm into ee={} : {}'.format(ee_id, e))
+            raise N2VCException(message="Error deploying charm: {}".format(e))
 
-        self.log.info('Configuration sw installed')
+        self.log.info("K8s proxy charm installed")
+        ee_id = N2VCJujuConnector._build_ee_id(
+            model_name=model_name,
+            application_name=application_name,
+            machine_id="k8s",
+        )
+
+        self._write_ee_id_db(db_dict=db_dict, ee_id=ee_id)
+
+        return ee_id
 
     async def get_ee_ssh_public__key(
         self,
         ee_id: str,
         db_dict: dict,
         progress_timeout: float = None,
-        total_timeout: float = None
+        total_timeout: float = None,
+        vca_id: str = None,
     ) -> str:
+        """
+        Get Execution environment ssh public key
+
+        :param: ee_id: the id of the execution environment returned by
+            create_execution_environment or register_execution_environment
+        :param: db_dict: where to write into database when the status changes.
+                            It contains a dict with
+                                {collection: <str>, filter: {},  path: <str>},
+                                e.g. {collection: "nsrs", filter:
+                                    {_id: <nsd-id>, path: "_admin.deployed.VCA.3"}
+        :param: progress_timeout: Progress timeout
+        :param: total_timeout: Total timeout
+        :param vca_id: VCA ID
+        :returns: public key of the execution environment
+                    For the case of juju proxy charm ssh-layered, it is the one
+                    returned by 'get-ssh-public-key' primitive.
+                    It raises a N2VC exception if fails
+        """
 
-        self.log.info('Generating priv/pub key pair and get pub key on ee_id: {}, db_dict: {}'.format(ee_id, db_dict))
-
-        if not self._authenticated:
-            await self._juju_login()
+        self.log.info(
+            (
+                "Generating priv/pub key pair and get pub key on ee_id: {}, db_dict: {}"
+            ).format(ee_id, db_dict)
+        )
+        libjuju = await self._get_libjuju(vca_id)
 
         # check arguments
         if ee_id is None or len(ee_id) == 0:
-            raise N2VCBadArgumentsException(message='ee_id is mandatory', bad_args=['ee_id'])
+            raise N2VCBadArgumentsException(
+                message="ee_id is mandatory", bad_args=["ee_id"]
+            )
         if db_dict is None:
-            raise N2VCBadArgumentsException(message='db_dict is mandatory', bad_args=['db_dict'])
+            raise N2VCBadArgumentsException(
+                message="db_dict is mandatory", bad_args=["db_dict"]
+            )
 
         try:
-            model_name, application_name, machine_id = N2VCJujuConnector._get_ee_id_components(ee_id=ee_id)
-            self.log.debug('model: {}, application: {}, machine: {}'.format(model_name, application_name, machine_id))
-        except Exception as e:
+            (
+                model_name,
+                application_name,
+                machine_id,
+            ) = N2VCJujuConnector._get_ee_id_components(ee_id=ee_id)
+            self.log.debug(
+                "model: {}, application: {}, machine: {}".format(
+                    model_name, application_name, machine_id
+                )
+            )
+        except Exception:
             raise N2VCBadArgumentsException(
-                message='ee_id={} is not a valid execution environment id'.format(ee_id),
-                bad_args=['ee_id']
+                message="ee_id={} is not a valid execution environment id".format(
+                    ee_id
+                ),
+                bad_args=["ee_id"],
             )
 
         # try to execute ssh layer primitives (if exist):
@@ -429,231 +636,369 @@ class N2VCJujuConnector(N2VCConnector):
 
         output = None
 
+        application_name = N2VCJujuConnector._format_app_name(application_name)
+
         # execute action: generate-ssh-key
         try:
-            output, status = await self._juju_execute_action(
+            output, _status = await libjuju.execute_action(
                 model_name=model_name,
                 application_name=application_name,
-                action_name='generate-ssh-key',
+                action_name="generate-ssh-key",
                 db_dict=db_dict,
                 progress_timeout=progress_timeout,
-                total_timeout=total_timeout
+                total_timeout=total_timeout,
             )
         except Exception as e:
-            self.log.info('Cannot execute action generate-ssh-key: {}\nContinuing...'.format(e))
+            self.log.info(
+                "Skipping exception while executing action generate-ssh-key: {}".format(
+                    e
+                )
+            )
 
         # execute action: get-ssh-public-key
         try:
-            output, status = await self._juju_execute_action(
+            output, _status = await libjuju.execute_action(
                 model_name=model_name,
                 application_name=application_name,
-                action_name='get-ssh-public-key',
+                action_name="get-ssh-public-key",
                 db_dict=db_dict,
                 progress_timeout=progress_timeout,
-                total_timeout=total_timeout
+                total_timeout=total_timeout,
             )
         except Exception as e:
-            msg = 'Cannot execute action get-ssh-public-key: {}\n'.format(e)
+            msg = "Cannot execute action get-ssh-public-key: {}\n".format(e)
             self.log.info(msg)
-            raise e
+            raise N2VCExecutionException(e, primitive_name="get-ssh-public-key")
 
         # return public key if exists
         return output["pubkey"] if "pubkey" in output else output
 
+    async def get_metrics(
+        self, model_name: str, application_name: str, vca_id: str = None
+    ) -> dict:
+        """
+        Get metrics from application
+
+        :param: model_name: Model name
+        :param: application_name: Application name
+        :param: vca_id: VCA ID
+
+        :return: Dictionary with obtained metrics
+        """
+        libjuju = await self._get_libjuju(vca_id)
+        return await libjuju.get_metrics(model_name, application_name)
+
     async def add_relation(
         self,
         ee_id_1: str,
         ee_id_2: str,
         endpoint_1: str,
-        endpoint_2: str
+        endpoint_2: str,
+        vca_id: str = None,
     ):
+        """
+        Add relation between two charmed endpoints
 
-        self.log.debug('adding new relation between {} and {}, endpoints: {}, {}'
-                   .format(ee_id_1, ee_id_2, endpoint_1, endpoint_2))
+        :param: ee_id_1: The id of the first execution environment
+        :param: ee_id_2: The id of the second execution environment
+        :param: endpoint_1: The endpoint in the first execution environment
+        :param: endpoint_2: The endpoint in the second execution environment
+        :param: vca_id: VCA ID
+        """
+        self.log.debug(
+            "adding new relation between {} and {}, endpoints: {}, {}".format(
+                ee_id_1, ee_id_2, endpoint_1, endpoint_2
+            )
+        )
+        libjuju = await self._get_libjuju(vca_id)
 
         # check arguments
         if not ee_id_1:
-            message = 'EE 1 is mandatory'
+            message = "EE 1 is mandatory"
             self.log.error(message)
-            raise N2VCBadArgumentsException(message=message, bad_args=['ee_id_1'])
+            raise N2VCBadArgumentsException(message=message, bad_args=["ee_id_1"])
         if not ee_id_2:
-            message = 'EE 2 is mandatory'
+            message = "EE 2 is mandatory"
             self.log.error(message)
-            raise N2VCBadArgumentsException(message=message, bad_args=['ee_id_2'])
+            raise N2VCBadArgumentsException(message=message, bad_args=["ee_id_2"])
         if not endpoint_1:
-            message = 'endpoint 1 is mandatory'
+            message = "endpoint 1 is mandatory"
             self.log.error(message)
-            raise N2VCBadArgumentsException(message=message, bad_args=['endpoint_1'])
+            raise N2VCBadArgumentsException(message=message, bad_args=["endpoint_1"])
         if not endpoint_2:
-            message = 'endpoint 2 is mandatory'
+            message = "endpoint 2 is mandatory"
             self.log.error(message)
-            raise N2VCBadArgumentsException(message=message, bad_args=['endpoint_2'])
-
-        if not self._authenticated:
-            await self._juju_login()
+            raise N2VCBadArgumentsException(message=message, bad_args=["endpoint_2"])
 
         # get the model, the applications and the machines from the ee_id's
-        model_1, app_1, machine_1 = self._get_ee_id_components(ee_id_1)
-        model_2, app_2, machine_2 = self._get_ee_id_components(ee_id_2)
+        model_1, app_1, _machine_1 = self._get_ee_id_components(ee_id_1)
+        model_2, app_2, _machine_2 = self._get_ee_id_components(ee_id_2)
 
         # model must be the same
         if model_1 != model_2:
-            message = 'EE models are not the same: {} vs {}'.format(ee_id_1, ee_id_2)
+            message = "EE models are not the same: {} vs {}".format(ee_id_1, ee_id_2)
             self.log.error(message)
-            raise N2VCBadArgumentsException(message=message, bad_args=['ee_id_1', 'ee_id_2'])
+            raise N2VCBadArgumentsException(
+                message=message, bad_args=["ee_id_1", "ee_id_2"]
+            )
 
         # add juju relations between two applications
         try:
-            await self._juju_add_relation(
+            await libjuju.add_relation(
                 model_name=model_1,
-                application_name_1=app_1,
-                application_name_2=app_2,
-                relation_1=endpoint_1,
-                relation_2=endpoint_2
+                endpoint_1="{}:{}".format(app_1, endpoint_1),
+                endpoint_2="{}:{}".format(app_2, endpoint_2),
             )
         except Exception as e:
-            message = 'Error adding relation between {} and {}'.format(ee_id_1, ee_id_2)
+            message = "Error adding relation between {} and {}: {}".format(
+                ee_id_1, ee_id_2, e
+            )
             self.log.error(message)
             raise N2VCException(message=message)
 
-    async def remove_relation(
-        self
-    ):
-        if not self._authenticated:
-            await self._juju_login()
+    async def remove_relation(self):
         # TODO
-        self.log.info('Method not implemented yet')
-        raise NotImplemented()
+        self.log.info("Method not implemented yet")
+        raise MethodNotImplemented()
 
-    async def deregister_execution_environments(
-        self
-    ):
-        if not self._authenticated:
-            await self._juju_login()
-        # TODO
-        self.log.info('Method not implemented yet')
-        raise NotImplemented()
+    async def deregister_execution_environments(self):
+        self.log.info("Method not implemented yet")
+        raise MethodNotImplemented()
 
     async def delete_namespace(
         self,
         namespace: str,
         db_dict: dict = None,
-        total_timeout: float = None
+        total_timeout: float = None,
+        vca_id: str = None,
     ):
-        self.log.info('Deleting namespace={}'.format(namespace))
-
-        if not self._authenticated:
-            await self._juju_login()
+        """
+        Remove a network scenario and its execution environments
+        :param: namespace: [<nsi-id>].<ns-id>
+        :param: db_dict: where to write into database when the status changes.
+                        It contains a dict with
+                            {collection: <str>, filter: {},  path: <str>},
+                            e.g. {collection: "nsrs", filter:
+                                {_id: <nsd-id>, path: "_admin.deployed.VCA.3"}
+        :param: total_timeout: Total timeout
+        :param: vca_id: VCA ID
+        """
+        self.log.info("Deleting namespace={}".format(namespace))
+        libjuju = await self._get_libjuju(vca_id)
 
         # check arguments
         if namespace is None:
-            raise N2VCBadArgumentsException(message='namespace is mandatory', bad_args=['namespace'])
+            raise N2VCBadArgumentsException(
+                message="namespace is mandatory", bad_args=["namespace"]
+            )
 
-        nsi_id, ns_id, vnf_id, vdu_id, vdu_count = self._get_namespace_components(namespace=namespace)
+        _nsi_id, ns_id, _vnf_id, _vdu_id, _vdu_count = self._get_namespace_components(
+            namespace=namespace
+        )
         if ns_id is not None:
             try:
-                await self._juju_destroy_model(
-                    model_name=ns_id,
-                    total_timeout=total_timeout
-                )
-            except N2VCNotFound:
-                raise
+                models = await libjuju.list_models(contains=ns_id)
+                for model in models:
+                    await libjuju.destroy_model(
+                        model_name=model, total_timeout=total_timeout
+                    )
             except Exception as e:
-                raise N2VCException(message='Error deleting namespace {} : {}'.format(namespace, e))
+                raise N2VCException(
+                    message="Error deleting namespace {} : {}".format(namespace, e)
+                )
         else:
-            raise N2VCBadArgumentsException(message='only ns_id is permitted to delete yet', bad_args=['namespace'])
+            raise N2VCBadArgumentsException(
+                message="only ns_id is permitted to delete yet", bad_args=["namespace"]
+            )
 
-        self.log.info('Namespace {} deleted'.format(namespace))
+        self.log.info("Namespace {} deleted".format(namespace))
 
     async def delete_execution_environment(
         self,
         ee_id: str,
         db_dict: dict = None,
-        total_timeout: float = None
+        total_timeout: float = None,
+        scaling_in: bool = False,
+        vca_id: str = None,
     ):
-        self.log.info('Deleting execution environment ee_id={}'.format(ee_id))
-
-        if not self._authenticated:
-            await self._juju_login()
+        """
+        Delete an execution environment
+        :param str ee_id: id of the execution environment to delete
+        :param dict db_dict: where to write into database when the status changes.
+                        It contains a dict with
+                            {collection: <str>, filter: {},  path: <str>},
+                            e.g. {collection: "nsrs", filter:
+                                {_id: <nsd-id>, path: "_admin.deployed.VCA.3"}
+        :param: total_timeout: Total timeout
+        :param: scaling_in: Boolean to indicate if is it a scaling in operation
+        :param: vca_id: VCA ID
+        """
+        self.log.info("Deleting execution environment ee_id={}".format(ee_id))
+        libjuju = await self._get_libjuju(vca_id)
 
         # check arguments
         if ee_id is None:
-            raise N2VCBadArgumentsException(message='ee_id is mandatory', bad_args=['ee_id'])
-
-        model_name, application_name, machine_id = self._get_ee_id_components(ee_id=ee_id)
+            raise N2VCBadArgumentsException(
+                message="ee_id is mandatory", bad_args=["ee_id"]
+            )
 
-        # destroy the application
+        model_name, application_name, _machine_id = self._get_ee_id_components(
+            ee_id=ee_id
+        )
         try:
-            await self._juju_destroy_application(model_name=model_name, application_name=application_name)
+            if not scaling_in:
+                # destroy the model
+                # TODO: should this be removed?
+                await libjuju.destroy_model(
+                    model_name=model_name,
+                    total_timeout=total_timeout,
+                )
+            else:
+                # destroy the application
+                await libjuju.destroy_application(
+                    model_name=model_name,
+                    application_name=application_name,
+                    total_timeout=total_timeout,
+                )
         except Exception as e:
-            raise N2VCException(message='Error deleting execution environment {} (application {}) : {}'
-                                .format(ee_id, application_name, e))
-
-        # destroy the machine
-        # try: 
-        #     await self._juju_destroy_machine(
-        #         model_name=model_name,
-        #         machine_id=machine_id,
-        #         total_timeout=total_timeout
-        #     )
-        # except Exception as e:
-        #     raise N2VCException(message='Error deleting execution environment {} (machine {}) : {}'
-        #                         .format(ee_id, machine_id, e))
-
-        self.log.info('Execution environment {} deleted'.format(ee_id))
+            raise N2VCException(
+                message=(
+                    "Error deleting execution environment {} (application {}) : {}"
+                ).format(ee_id, application_name, e)
+            )
+
+        self.log.info("Execution environment {} deleted".format(ee_id))
 
     async def exec_primitive(
-            self,
-            ee_id: str,
-            primitive_name: str,
-            params_dict: dict,
-            db_dict: dict = None,
-            progress_timeout: float = None,
-            total_timeout: float = None
+        self,
+        ee_id: str,
+        primitive_name: str,
+        params_dict: dict,
+        db_dict: dict = None,
+        progress_timeout: float = None,
+        total_timeout: float = None,
+        vca_id: str = None,
     ) -> str:
+        """
+        Execute a primitive in the execution environment
+
+        :param: ee_id: the one returned by create_execution_environment or
+            register_execution_environment
+        :param: primitive_name: must be one defined in the software. There is one
+            called 'config', where, for the proxy case, the 'credentials' of VM are
+            provided
+        :param: params_dict: parameters of the action
+        :param: db_dict: where to write into database when the status changes.
+                        It contains a dict with
+                            {collection: <str>, filter: {},  path: <str>},
+                            e.g. {collection: "nsrs", filter:
+                                {_id: <nsd-id>, path: "_admin.deployed.VCA.3"}
+        :param: progress_timeout: Progress timeout
+        :param: total_timeout: Total timeout
+        :param: vca_id: VCA ID
+        :returns str: primitive result, if ok. It raises exceptions in case of fail
+        """
 
-        self.log.info('Executing primitive: {} on ee: {}, params: {}'.format(primitive_name, ee_id, params_dict))
-
-        if not self._authenticated:
-            await self._juju_login()
+        self.log.info(
+            "Executing primitive: {} on ee: {}, params: {}".format(
+                primitive_name, ee_id, params_dict
+            )
+        )
+        libjuju = await self._get_libjuju(vca_id)
 
         # check arguments
         if ee_id is None or len(ee_id) == 0:
-            raise N2VCBadArgumentsException(message='ee_id is mandatory', bad_args=['ee_id'])
+            raise N2VCBadArgumentsException(
+                message="ee_id is mandatory", bad_args=["ee_id"]
+            )
         if primitive_name is None or len(primitive_name) == 0:
-            raise N2VCBadArgumentsException(message='action_name is mandatory', bad_args=['action_name'])
+            raise N2VCBadArgumentsException(
+                message="action_name is mandatory", bad_args=["action_name"]
+            )
         if params_dict is None:
             params_dict = dict()
 
         try:
-            model_name, application_name, machine_id = N2VCJujuConnector._get_ee_id_components(ee_id=ee_id)
+            (
+                model_name,
+                application_name,
+                _machine_id,
+            ) = N2VCJujuConnector._get_ee_id_components(ee_id=ee_id)
         except Exception:
             raise N2VCBadArgumentsException(
-                message='ee_id={} is not a valid execution environment id'.format(ee_id),
-                bad_args=['ee_id']
+                message="ee_id={} is not a valid execution environment id".format(
+                    ee_id
+                ),
+                bad_args=["ee_id"],
             )
 
-        if primitive_name == 'config':
+        if primitive_name == "config":
             # Special case: config primitive
             try:
-                await self._juju_configure_application(
+                await libjuju.configure_application(
                     model_name=model_name,
                     application_name=application_name,
                     config=params_dict,
-                    db_dict=db_dict,
-                    progress_timeout=progress_timeout,
-                    total_timeout=total_timeout
                 )
+                actions = await libjuju.get_actions(
+                    application_name=application_name,
+                    model_name=model_name,
+                )
+                self.log.debug(
+                    "Application {} has these actions: {}".format(
+                        application_name, actions
+                    )
+                )
+                if "verify-ssh-credentials" in actions:
+                    # execute verify-credentials
+                    num_retries = 20
+                    retry_timeout = 15.0
+                    for _ in range(num_retries):
+                        try:
+                            self.log.debug("Executing action verify-ssh-credentials...")
+                            output, ok = await libjuju.execute_action(
+                                model_name=model_name,
+                                application_name=application_name,
+                                action_name="verify-ssh-credentials",
+                                db_dict=db_dict,
+                                progress_timeout=progress_timeout,
+                                total_timeout=total_timeout,
+                            )
+
+                            if ok == "failed":
+                                self.log.debug(
+                                    "Error executing verify-ssh-credentials: {}. Retrying..."
+                                )
+                                await asyncio.sleep(retry_timeout)
+
+                                continue
+                            self.log.debug("Result: {}, output: {}".format(ok, output))
+                            break
+                        except asyncio.CancelledError:
+                            raise
+                    else:
+                        self.log.error(
+                            "Error executing verify-ssh-credentials after {} retries. ".format(
+                                num_retries
+                            )
+                        )
+                else:
+                    msg = "Action verify-ssh-credentials does not exist in application {}".format(
+                        application_name
+                    )
+                    self.log.debug(msg=msg)
             except Exception as e:
-                self.log.error('Error configuring juju application: {}'.format(e))
+                self.log.error("Error configuring juju application: {}".format(e))
                 raise N2VCExecutionException(
-                    message='Error configuring application into ee={} : {}'.format(ee_id, e),
-                    primitive_name=primitive_name
+                    message="Error configuring application into ee={} : {}".format(
+                        ee_id, e
+                    ),
+                    primitive_name=primitive_name,
                 )
-            return 'CONFIG OK'
+            return "CONFIG OK"
         else:
             try:
-                output, status = await self._juju_execute_action(
+                output, status = await libjuju.execute_action(
                     model_name=model_name,
                     application_name=application_name,
                     action_name=primitive_name,
@@ -662,57 +1007,92 @@ class N2VCJujuConnector(N2VCConnector):
                     total_timeout=total_timeout,
                     **params_dict
                 )
-                if status == 'completed':
+                if status == "completed":
                     return output
                 else:
-                    raise Exception('status is not completed: {}'.format(status))
+                    raise Exception("status is not completed: {}".format(status))
             except Exception as e:
-                self.log.error('Error executing primitive {}: {}'.format(primitive_name, e))
+                self.log.error(
+                    "Error executing primitive {}: {}".format(primitive_name, e)
+                )
                 raise N2VCExecutionException(
-                    message='Error executing primitive {} into ee={} : {}'.format(primitive_name, ee_id, e),
-                    primitive_name=primitive_name
+                    message="Error executing primitive {} into ee={} : {}".format(
+                        primitive_name, ee_id, e
+                    ),
+                    primitive_name=primitive_name,
                 )
 
-    async def disconnect(self):
-        self.log.info('closing juju N2VC...')
-        await self._juju_logout()
+    async def disconnect(self, vca_id: str = None):
+        """
+        Disconnect from VCA
+
+        :param: vca_id: VCA ID
+        """
+        self.log.info("closing juju N2VC...")
+        libjuju = await self._get_libjuju(vca_id)
+        try:
+            await libjuju.disconnect()
+        except Exception as e:
+            raise N2VCConnectionException(
+                message="Error disconnecting controller: {}".format(e),
+                url=libjuju.vca_connection.data.endpoints,
+            )
 
     """
-    ##################################################################################################
-    ########################################## P R I V A T E #########################################
-    ##################################################################################################
+####################################################################################
+################################### P R I V A T E ##################################
+####################################################################################
     """
 
-    def _write_ee_id_db(
-            self,
-            db_dict: dict,
-            ee_id: str
-    ):
+    async def _get_libjuju(self, vca_id: str = None) -> Libjuju:
+        """
+        Get libjuju object
+
+        :param: vca_id: VCA ID
+                        If None, get a libjuju object with a Connection to the default VCA
+                        Else, geta libjuju object with a Connection to the specified VCA
+        """
+        if not vca_id:
+            while self.loading_libjuju.locked():
+                await asyncio.sleep(0.1)
+            if not self.libjuju:
+                async with self.loading_libjuju:
+                    vca_connection = await get_connection(self._store)
+                    self.libjuju = Libjuju(vca_connection, loop=self.loop, log=self.log)
+            return self.libjuju
+        else:
+            vca_connection = await get_connection(self._store, vca_id)
+            return Libjuju(
+                vca_connection,
+                loop=self.loop,
+                log=self.log,
+                n2vc=self,
+            )
+
+    def _write_ee_id_db(self, db_dict: dict, ee_id: str):
 
         # write ee_id to database: _admin.deployed.VCA.x
         try:
-            the_table = db_dict['collection']
-            the_filter = db_dict['filter']
-            the_path = db_dict['path']
-            if not the_path[-1] == '.':
-                the_path = the_path + '.'
-            update_dict = {the_path + 'ee_id': ee_id}
+            the_table = db_dict["collection"]
+            the_filter = db_dict["filter"]
+            the_path = db_dict["path"]
+            if not the_path[-1] == ".":
+                the_path = the_path + "."
+            update_dict = {the_path + "ee_id": ee_id}
             # self.log.debug('Writing ee_id to database: {}'.format(the_path))
             self.db.set_one(
                 table=the_table,
                 q_filter=the_filter,
                 update_dict=update_dict,
-                fail_on_empty=True
+                fail_on_empty=True,
             )
+        except asyncio.CancelledError:
+            raise
         except Exception as e:
-            self.log.error('Error writing ee_id to database: {}'.format(e))
+            self.log.error("Error writing ee_id to database: {}".format(e))
 
     @staticmethod
-    def _build_ee_id(
-            model_name: str,
-            application_name: str,
-            machine_id: str
-    ):
+    def _build_ee_id(model_name: str, application_name: str, machine_id: str):
         """
         Build an execution environment id form model, application and machine
         :param model_name:
@@ -721,12 +1101,10 @@ class N2VCJujuConnector(N2VCConnector):
         :return:
         """
         # id for the execution environment
-        return '{}.{}.{}'.format(model_name, application_name, machine_id)
+        return "{}.{}.{}".format(model_name, application_name, machine_id)
 
     @staticmethod
-    def _get_ee_id_components(
-            ee_id: str
-    ) -> (str, str, str):
+    def _get_ee_id_components(ee_id: str) -> (str, str, str):
         """
         Get model, application and machine components from an execution environment id
         :param ee_id:
@@ -737,7 +1115,7 @@ class N2VCJujuConnector(N2VCConnector):
             return None, None, None
 
         # split components of id
-        parts = ee_id.split('.')
+        parts = ee_id.split(".")
         model_name = parts[0]
         application_name = parts[1]
         machine_id = parts[2]
@@ -753,705 +1131,31 @@ class N2VCJujuConnector(N2VCConnector):
         # TODO: Enforce the Juju 50-character application limit
 
         # split namespace components
-        _, _, vnf_id, vdu_id, vdu_count = self._get_namespace_components(namespace=namespace)
+        _, _, vnf_id, vdu_id, vdu_count = self._get_namespace_components(
+            namespace=namespace
+        )
 
         if vnf_id is None or len(vnf_id) == 0:
-            vnf_id = ''
+            vnf_id = ""
         else:
             # Shorten the vnf_id to its last twelve characters
-            vnf_id = 'vnf-' + vnf_id[-12:]
+            vnf_id = "vnf-" + vnf_id[-12:]
 
         if vdu_id is None or len(vdu_id) == 0:
-            vdu_id = ''
+            vdu_id = ""
         else:
             # Shorten the vdu_id to its last twelve characters
-            vdu_id = '-vdu-' + vdu_id[-12:]
+            vdu_id = "-vdu-" + vdu_id[-12:]
 
         if vdu_count is None or len(vdu_count) == 0:
-            vdu_count = ''
+            vdu_count = ""
         else:
-            vdu_count = '-cnt-' + vdu_count
+            vdu_count = "-cnt-" + vdu_count
 
-        application_name = 'app-{}{}{}'.format(vnf_id, vdu_id, vdu_count)
+        application_name = "app-{}{}{}".format(vnf_id, vdu_id, vdu_count)
 
         return N2VCJujuConnector._format_app_name(application_name)
 
-    async def _juju_create_machine(
-            self,
-            model_name: str,
-            application_name: str,
-            machine_id: str = None,
-            db_dict: dict = None,
-            progress_timeout: float = None,
-            total_timeout: float = None
-    ) -> Machine:
-
-        self.log.debug('creating machine in model: {}, existing machine id: {}'.format(model_name, machine_id))
-
-        # get juju model and observer (create model if needed)
-        model = await self._juju_get_model(model_name=model_name)
-        observer = self.juju_observers[model_name]
-
-        # find machine id in model
-        machine = None
-        if machine_id is not None:
-            self.log.debug('Finding existing machine id {} in model'.format(machine_id))
-            # get juju existing machines in the model
-            existing_machines = await model.get_machines()
-            if machine_id in existing_machines:
-                self.log.debug('Machine id {} found in model (reusing it)'.format(machine_id))
-                machine = model.machines[machine_id]
-
-        if machine is None:
-            self.log.debug('Creating a new machine in juju...')
-            # machine does not exist, create it and wait for it
-            machine = await model.add_machine(
-                spec=None,
-                constraints=None,
-                disks=None,
-                series='xenial'
-            )
-
-            # register machine with observer
-            observer.register_machine(machine=machine, db_dict=db_dict)
-
-            # id for the execution environment
-            ee_id = N2VCJujuConnector._build_ee_id(
-                model_name=model_name,
-                application_name=application_name,
-                machine_id=str(machine.entity_id)
-            )
-
-            # write ee_id in database
-            self._write_ee_id_db(
-                db_dict=db_dict,
-                ee_id=ee_id
-            )
-
-            # wait for machine creation
-            await observer.wait_for_machine(
-                machine_id=str(machine.entity_id),
-                progress_timeout=progress_timeout,
-                total_timeout=total_timeout
-            )
-
-        else:
-
-            self.log.debug('Reusing old machine pending')
-
-            # register machine with observer
-            observer.register_machine(machine=machine, db_dict=db_dict)
-
-            # machine does exist, but it is in creation process (pending), wait for create finalisation
-            await observer.wait_for_machine(
-                machine_id=machine.entity_id,
-                progress_timeout=progress_timeout,
-                total_timeout=total_timeout)
-
-        self.log.debug("Machine ready at " + str(machine.dns_name))
-        return machine
-
-    async def _juju_provision_machine(
-            self,
-            model_name: str,
-            hostname: str,
-            username: str,
-            private_key_path: str,
-            db_dict: dict = None,
-            progress_timeout: float = None,
-            total_timeout: float = None
-    ) -> str:
-
-        if not self.api_proxy:
-            msg = 'Cannot provision machine: api_proxy is not defined'
-            self.log.error(msg=msg)
-            raise N2VCException(message=msg)
-
-        self.log.debug('provisioning machine. model: {}, hostname: {}, username: {}'.format(model_name, hostname, username))
-
-        if not self._authenticated:
-            await self._juju_login()
-
-        # get juju model and observer
-        model = await self._juju_get_model(model_name=model_name)
-        observer = self.juju_observers[model_name]
-
-        # TODO check if machine is already provisioned
-        machine_list = await model.get_machines()
-
-        provisioner = SSHProvisioner(
-            host=hostname,
-            user=username,
-            private_key_path=private_key_path,
-            log=self.log
-        )
-
-        params = None
-        try:
-            params = provisioner.provision_machine()
-        except Exception as ex:
-            msg = "Exception provisioning machine: {}".format(ex)
-            self.log.error(msg)
-            raise N2VCException(message=msg)
-
-        params.jobs = ['JobHostUnits']
-
-        connection = model.connection()
-
-        # Submit the request.
-        self.log.debug("Adding machine to model")
-        client_facade = client.ClientFacade.from_connection(connection)
-        results = await client_facade.AddMachines(params=[params])
-        error = results.machines[0].error
-        if error:
-            msg = "Error adding machine: {}}".format(error.message)
-            self.log.error(msg=msg)
-            raise ValueError(msg)
-
-        machine_id = results.machines[0].machine
-
-        # Need to run this after AddMachines has been called,
-        # as we need the machine_id
-        self.log.debug("Installing Juju agent into machine {}".format(machine_id))
-        asyncio.ensure_future(provisioner.install_agent(
-            connection=connection,
-            nonce=params.nonce,
-            machine_id=machine_id,
-            api=self.api_proxy,
-        ))
-
-        # wait for machine in model (now, machine is not yet in model, so we must wait for it)
-        machine = None
-        for i in range(10):
-            machine_list = await model.get_machines()
-            if machine_id in machine_list:
-                self.log.debug('Machine {} found in model!'.format(machine_id))
-                machine = model.machines.get(machine_id)
-                break
-            await asyncio.sleep(2)
-
-        if machine is None:
-            msg = 'Machine {} not found in model'.format(machine_id)
-            self.log.error(msg=msg)
-            raise Exception(msg)
-
-        # register machine with observer
-        observer.register_machine(machine=machine, db_dict=db_dict)
-
-        # wait for machine creation
-        self.log.debug('waiting for provision finishes... {}'.format(machine_id))
-        await observer.wait_for_machine(
-            machine_id=machine_id,
-            progress_timeout=progress_timeout,
-            total_timeout=total_timeout
-        )
-
-        self.log.debug("Machine provisioned {}".format(machine_id))
-
-        return machine_id
-
-    async def _juju_deploy_charm(
-            self,
-            model_name: str,
-            application_name: str,
-            charm_path: str,
-            machine_id: str,
-            db_dict: dict,
-            progress_timeout: float = None,
-            total_timeout: float = None,
-            config: dict = None
-    ) -> (Application, int):
-
-        # get juju model and observer
-        model = await self._juju_get_model(model_name=model_name)
-        observer = self.juju_observers[model_name]
-
-        # check if application already exists
-        application = None
-        if application_name in model.applications:
-            application = model.applications[application_name]
-
-        if application is None:
-
-            # application does not exist, create it and wait for it
-            self.log.debug('deploying application {} to machine {}, model {}'
-                       .format(application_name, machine_id, model_name))
-            self.log.debug('charm: {}'.format(charm_path))
-            series = 'xenial'
-            # series = None
-            application = await model.deploy(
-                entity_url=charm_path,
-                application_name=application_name,
-                channel='stable',
-                num_units=1,
-                series=series,
-                to=machine_id,
-                config=config
-            )
-
-            # register application with observer
-            observer.register_application(application=application, db_dict=db_dict)
-
-            self.log.debug('waiting for application deployed... {}'.format(application.entity_id))
-            retries = await observer.wait_for_application(
-                application_id=application.entity_id,
-                progress_timeout=progress_timeout,
-                total_timeout=total_timeout)
-            self.log.debug('application deployed')
-
-        else:
-
-            # register application with observer
-            observer.register_application(application=application, db_dict=db_dict)
-
-            # application already exists, but not finalised
-            self.log.debug('application already exists, waiting for deployed...')
-            retries = await observer.wait_for_application(
-                application_id=application.entity_id,
-                progress_timeout=progress_timeout,
-                total_timeout=total_timeout)
-            self.log.debug('application deployed')
-
-        return application, retries
-
-    async def _juju_execute_action(
-            self,
-            model_name: str,
-            application_name: str,
-            action_name: str,
-            db_dict: dict,
-            progress_timeout: float = None,
-            total_timeout: float = None,
-            **kwargs
-    ) -> Action:
-
-        # get juju model and observer
-        model = await self._juju_get_model(model_name=model_name)
-        observer = self.juju_observers[model_name]
-
-        application = await self._juju_get_application(model_name=model_name, application_name=application_name)
-
-        unit = None
-        for u in application.units:
-            if await u.is_leader_from_status():
-                unit = u
-        if unit is not None:
-            actions = await application.get_actions()
-            if action_name in actions:
-                self.log.debug('executing action "{}" using params: {}'.format(action_name, kwargs))
-                action = await unit.run_action(action_name, **kwargs)
-
-                # register action with observer
-                observer.register_action(action=action, db_dict=db_dict)
-
-                await observer.wait_for_action(
-                    action_id=action.entity_id,
-                    progress_timeout=progress_timeout,
-                    total_timeout=total_timeout)
-                self.log.debug('action completed with status: {}'.format(action.status))
-                output = await model.get_action_output(action_uuid=action.entity_id)
-                status = await model.get_action_status(uuid_or_prefix=action.entity_id)
-                if action.entity_id in status:
-                    status = status[action.entity_id]
-                else:
-                    status = 'failed'
-                return output, status
-
-        raise N2VCExecutionException(
-            message='Cannot execute action on charm',
-            primitive_name=action_name
-        )
-
-    async def _juju_configure_application(
-            self,
-            model_name: str,
-            application_name: str,
-            config: dict,
-            db_dict: dict,
-            progress_timeout: float = None,
-            total_timeout: float = None
-    ):
-
-        # get the application
-        application = await self._juju_get_application(model_name=model_name, application_name=application_name)
-
-        self.log.debug('configuring the application {} -> {}'.format(application_name, config))
-        res = await application.set_config(config)
-        self.log.debug('application {} configured. res={}'.format(application_name, res))
-
-        # Verify the config is set
-        new_conf = await application.get_config()
-        for key in config:
-            value = new_conf[key]['value']
-            self.log.debug('    {} = {}'.format(key, value))
-            if config[key] != value:
-                raise N2VCException(
-                    message='key {} is not configured correctly {} != {}'.format(key, config[key], new_conf[key])
-                )
-
-        # check if 'verify-ssh-credentials' action exists
-        # unit = application.units[0]
-        actions = await application.get_actions()
-        if 'verify-ssh-credentials' not in actions:
-            msg = 'Action verify-ssh-credentials does not exist in application {}'.format(application_name)
-            self.log.debug(msg=msg)
-            return False
-
-        # execute verify-credentials
-        num_retries = 20
-        retry_timeout = 15.0
-        for i in range(num_retries):
-            try:
-                self.log.debug('Executing action verify-ssh-credentials...')
-                output, ok = await self._juju_execute_action(
-                    model_name=model_name,
-                    application_name=application_name,
-                    action_name='verify-ssh-credentials',
-                    db_dict=db_dict,
-                    progress_timeout=progress_timeout,
-                    total_timeout=total_timeout
-                )
-                self.log.debug('Result: {}, output: {}'.format(ok, output))
-                return True
-            except Exception as e:
-                self.log.debug('Error executing verify-ssh-credentials: {}. Retrying...'.format(e))
-                await asyncio.sleep(retry_timeout)
-        else:
-            self.log.error('Error executing verify-ssh-credentials after {} retries. '.format(num_retries))
-            return False
-
-    async def _juju_get_application(
-            self,
-            model_name: str,
-            application_name: str
-    ):
-        """Get the deployed application."""
-
-        model = await self._juju_get_model(model_name=model_name)
-
-        application_name = N2VCJujuConnector._format_app_name(application_name)
-
-        if model.applications and application_name in model.applications:
-            return model.applications[application_name]
-        else:
-            raise N2VCException(message='Cannot get application {} from model {}'.format(application_name, model_name))
-
-    async def _juju_get_model(self, model_name: str) -> Model:
-        """ Get a model object from juju controller
-        If the model does not exits, it creates it.
-
-        :param str model_name: name of the model
-        :returns Model: model obtained from juju controller or Exception
-        """
-
-        # format model name
-        model_name = N2VCJujuConnector._format_model_name(model_name)
-
-        if model_name in self.juju_models:
-            return self.juju_models[model_name]
-
-        if self._creating_model:
-            self.log.debug('Another coroutine is creating a model. Wait...')
-        while self._creating_model:
-            # another coroutine is creating a model, wait
-            await asyncio.sleep(0.1)
-            # retry (perhaps another coroutine has created the model meanwhile)
-            if model_name in self.juju_models:
-                return self.juju_models[model_name]
-
-        try:
-            self._creating_model = True
-
-            # get juju model names from juju
-            model_list = await self.controller.list_models()
-
-            if model_name not in model_list:
-                self.log.info('Model {} does not exist. Creating new model...'.format(model_name))
-                config_dict = {'authorized-keys': self.public_key}
-                if self.apt_mirror:
-                    config_dict['apt-mirror'] = self.apt_mirror
-                if not self.enable_os_upgrade:
-                    config_dict['enable-os-refresh-update'] = False
-                    config_dict['enable-os-upgrade'] = False
-
-                model = await self.controller.add_model(
-                    model_name=model_name,
-                    config=config_dict,
-                    cloud_name=self.cloud,
-                )
-                self.log.info('New model created, name={}'.format(model_name))
-            else:
-                self.log.debug('Model already exists in juju. Getting model {}'.format(model_name))
-                model = await self.controller.get_model(model_name)
-                self.log.debug('Existing model in juju, name={}'.format(model_name))
-
-            self.juju_models[model_name] = model
-            self.juju_observers[model_name] = JujuModelObserver(n2vc=self, model=model)
-            return model
-
-        except Exception as e:
-            msg = 'Cannot get model {}. Exception: {}'.format(model_name, e)
-            self.log.error(msg)
-            raise N2VCException(msg)
-        finally:
-            self._creating_model = False
-
-    async def _juju_add_relation(
-            self,
-            model_name: str,
-            application_name_1: str,
-            application_name_2: str,
-            relation_1: str,
-            relation_2: str
-    ):
-
-        # get juju model and observer
-        model = await self._juju_get_model(model_name=model_name)
-
-        r1 = '{}:{}'.format(application_name_1, relation_1)
-        r2 = '{}:{}'.format(application_name_2, relation_2)
-
-        self.log.debug('adding relation: {} -> {}'.format(r1, r2))
-        try:
-            await model.add_relation(relation1=r1, relation2=r2)
-        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
-            # another execption, raise it
-            raise e
-
-    async def _juju_destroy_application(
-        self,
-        model_name: str,
-        application_name: str
-    ):
-
-        self.log.debug('Destroying application {} in model {}'.format(application_name, model_name))
-
-        # get juju model and observer
-        model = await self._juju_get_model(model_name=model_name)
-        observer = self.juju_observers[model_name]
-
-        application = model.applications.get(application_name)
-        if application:
-            observer.unregister_application(application_name)
-            await application.destroy()
-        else:
-            self.log.debug('Application not found: {}'.format(application_name))
-
-    async def _juju_destroy_machine(
-        self,
-        model_name: str,
-        machine_id: str,
-        total_timeout: float = None
-    ):
-
-        self.log.debug('Destroying machine {} in model {}'.format(machine_id, model_name))
-
-        if total_timeout is None:
-            total_timeout = 3600
-
-        # get juju model and observer
-        model = await self._juju_get_model(model_name=model_name)
-        observer = self.juju_observers[model_name]
-
-        machines = await model.get_machines()
-        if machine_id in machines:
-            machine = model.machines[machine_id]
-            observer.unregister_machine(machine_id)
-            # TODO: change this by machine.is_manual when this is upstreamed: https://github.com/juju/python-libjuju/pull/396
-            if "instance-id" in machine.safe_data and machine.safe_data[
-                "instance-id"
-            ].startswith("manual:"):
-                self.log.debug("machine.destroy(force=True) started.")
-                await machine.destroy(force=True)
-                self.log.debug("machine.destroy(force=True) passed.")
-                # max timeout
-                end = time.time() + total_timeout
-                # wait for machine removal
-                machines = await model.get_machines()
-                while machine_id in machines and time.time() < end:
-                    self.log.debug("Waiting for machine {} is destroyed".format(machine_id))
-                    await asyncio.sleep(0.5)
-                    machines = await model.get_machines()
-                self.log.debug("Machine destroyed: {}".format(machine_id))
-        else:
-            self.log.debug('Machine not found: {}'.format(machine_id))
-
-    async def _juju_destroy_model(
-            self,
-            model_name: str,
-            total_timeout: float = None
-    ):
-
-        self.log.debug('Destroying model {}'.format(model_name))
-
-        if total_timeout is None:
-            total_timeout = 3600
-
-        model = await self._juju_get_model(model_name=model_name)
-
-        if not model:
-            raise N2VCNotFound(
-                message="Model {} does not exist".format(model_name)
-            )
-
-        uuid = model.info.uuid
-
-        # destroy applications
-        for application_name in model.applications:
-            try:
-                await self._juju_destroy_application(model_name=model_name, application_name=application_name)
-            except Exception as e:
-                self.log.error(
-                    "Error destroying application {} in model {}: {}".format(
-                        application_name,
-                        model_name,
-                        e
-                    )
-                )
-
-        # destroy machines
-        machines = await model.get_machines()
-        for machine_id in machines:
-            try:
-                await self._juju_destroy_machine(model_name=model_name, machine_id=machine_id)
-            except Exception as e:
-                # ignore exceptions destroying machine
-                pass
-
-        await self._juju_disconnect_model(model_name=model_name)
-
-        self.log.debug('destroying model {}...'.format(model_name))
-        await self.controller.destroy_model(uuid)
-        self.log.debug('model destroy requested {}'.format(model_name))
-
-        # wait for model is completely destroyed
-        end = time.time() + total_timeout
-        while time.time() < end:
-            self.log.debug('Waiting for model is destroyed...')
-            try:
-                # await self.controller.get_model(uuid)
-                models = await self.controller.list_models()
-                if model_name not in models:
-                    self.log.debug('The model {} ({}) was destroyed'.format(model_name, uuid))
-                    return
-            except Exception as e:
-                pass
-            await asyncio.sleep(1.0)
-
-    async def _juju_login(self):
-        """Connect to juju controller
-
-        """
-
-        # if already authenticated, exit function
-        if self._authenticated:
-            return
-
-        # if connecting, wait for finish
-        # another task could be trying to connect in parallel
-        while self._connecting:
-            await asyncio.sleep(0.1)
-
-        # double check after other task has finished
-        if self._authenticated:
-            return
-
-        try:
-            self._connecting = True
-            self.log.info(
-                'connecting to juju controller: {} {}:{} ca_cert: {}'
-                .format(self.url, self.username, self.secret, '\n'+self.ca_cert if self.ca_cert else 'None'))
-
-            # Create controller object
-            self.controller = Controller(loop=self.loop)
-            # Connect to controller
-            await self.controller.connect(
-                endpoint=self.url,
-                username=self.username,
-                password=self.secret,
-                cacert=self.ca_cert
-            )
-            self._authenticated = True
-            self.log.info('juju controller connected')
-        except Exception as e:
-            message = 'Exception connecting to juju: {}'.format(e)
-            self.log.error(message)
-            raise N2VCConnectionException(
-                message=message,
-                url=self.url
-            )
-        finally:
-            self._connecting = False
-
-    async def _juju_logout(self):
-        """Logout of the Juju controller."""
-        if not self._authenticated:
-            return False
-
-        # disconnect all models
-        for model_name in self.juju_models:
-            try:
-                await self._juju_disconnect_model(model_name)
-            except Exception as e:
-                self.log.error('Error disconnecting model {} : {}'.format(model_name, e))
-                # continue with next model...
-
-        self.log.info("Disconnecting controller")
-        try:
-            await self.controller.disconnect()
-        except Exception as e:
-            raise N2VCConnectionException(message='Error disconnecting controller: {}'.format(e), url=self.url)
-
-        self.controller = None
-        self._authenticated = False
-        self.log.info('disconnected')
-
-    async def _juju_disconnect_model(
-        self,
-        model_name: str
-    ):
-        self.log.debug("Disconnecting model {}".format(model_name))
-        if model_name in self.juju_models:
-            await self.juju_models[model_name].disconnect()
-            self.juju_models[model_name] = None
-            self.juju_observers[model_name] = None
-        else:
-            self.warning('Cannot disconnect model: {}'.format(model_name))
-
-    def _create_juju_public_key(self):
-        """Recreate the Juju public key on lcm container, if needed
-        Certain libjuju commands expect to be run from the same machine as Juju
-         is bootstrapped to. This method will write the public key to disk in
-         that location: ~/.local/share/juju/ssh/juju_id_rsa.pub
-        """
-
-        # Make sure that we have a public key before writing to disk
-        if self.public_key is None or len(self.public_key) == 0:
-            if 'OSMLCM_VCA_PUBKEY' in os.environ:
-                self.public_key = os.getenv('OSMLCM_VCA_PUBKEY', '')
-                if len(self.public_key) == 0:
-                    return
-            else:
-                return
-
-        pk_path = "{}/.local/share/juju/ssh".format(os.path.expanduser('~'))
-        file_path = "{}/juju_id_rsa.pub".format(pk_path)
-        self.log.debug('writing juju public key to file:\n{}\npublic key: {}'.format(file_path, self.public_key))
-        if not os.path.exists(pk_path):
-            # create path and write file
-            os.makedirs(pk_path)
-            with open(file_path, 'w') as f:
-                self.log.debug('Creating juju public key file: {}'.format(file_path))
-                f.write(self.public_key)
-        else:
-            self.log.debug('juju public key file already exists: {}'.format(file_path))
-
     @staticmethod
     def _format_model_name(name: str) -> str:
         """Format the name of the model.
@@ -1459,7 +1163,7 @@ class N2VCJujuConnector(N2VCConnector):
         Model names may only contain lowercase letters, digits and hyphens
         """
 
-        return name.replace('_', '-').replace(' ', '-').lower()
+        return name.replace("_", "-").replace(" ", "-").lower()
 
     @staticmethod
     def _format_app_name(name: str) -> str:
@@ -1480,24 +1184,35 @@ class N2VCJujuConnector(N2VCConnector):
                     return False
             return True
 
-        new_name = name.replace('_', '-')
-        new_name = new_name.replace(' ', '-')
+        new_name = name.replace("_", "-")
+        new_name = new_name.replace(" ", "-")
         new_name = new_name.lower()
-        while new_name.find('--') >= 0:
-            new_name = new_name.replace('--', '-')
-        groups = new_name.split('-')
+        while new_name.find("--") >= 0:
+            new_name = new_name.replace("--", "-")
+        groups = new_name.split("-")
 
         # find 'all numbers' groups and prefix them with a letter
-        app_name = ''
+        app_name = ""
         for i in range(len(groups)):
             group = groups[i]
             if all_numbers(group):
-                group = 'z' + group
+                group = "z" + group
             if i > 0:
-                app_name += '-'
+                app_name += "-"
             app_name += group
 
         if app_name[0].isdigit():
-            app_name = 'z' + app_name
+            app_name = "z" + app_name
 
         return app_name
+
+    async def validate_vca(self, vca_id: str):
+        """
+        Validate a VCA by connecting/disconnecting to/from it
+
+        :param: vca_id: VCA ID
+        """
+        vca_connection = await get_connection(self._store, vca_id=vca_id)
+        libjuju = Libjuju(vca_connection, loop=self.loop, log=self.log, n2vc=self)
+        controller = await libjuju.get_controller()
+        await libjuju.disconnect_controller(controller)