Refactors code and adds unit tests

Change-Id: Ia14034679af8fc7e9ac91a1bfb766e4b99ec9e39
Signed-off-by: Benjamin Diaz <bdiaz@whitestack.com>
diff --git a/osm_mon/evaluator/backends/__init__.py b/osm_mon/evaluator/backends/__init__.py
new file mode 100644
index 0000000..4450364
--- /dev/null
+++ b/osm_mon/evaluator/backends/__init__.py
@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2018 Whitestack, LLC
+# *************************************************************
+
+# This file is part of OSM Monitoring module
+# All Rights Reserved to Whitestack, LLC
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+
+#         http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: bdiaz@whitestack.com or glavado@whitestack.com
+##
diff --git a/osm_mon/evaluator/backends/base.py b/osm_mon/evaluator/backends/base.py
new file mode 100644
index 0000000..0e9fc0d
--- /dev/null
+++ b/osm_mon/evaluator/backends/base.py
@@ -0,0 +1,30 @@
+# Copyright 2018 Whitestack, LLC
+# *************************************************************
+
+# This file is part of OSM Monitoring module
+# All Rights Reserved to Whitestack, LLC
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+
+#         http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: bdiaz@whitestack.com or glavado@whitestack.com
+##
+from osm_mon.core.config import Config
+
+
+class BaseBackend:
+    def __init__(self, config: Config):
+        pass
+
+    def get_metric_value(self, metric_name, nsr_id, vdur_name, vnf_member_index):
+        pass
diff --git a/osm_mon/evaluator/backends/prometheus.py b/osm_mon/evaluator/backends/prometheus.py
new file mode 100644
index 0000000..9ff50d6
--- /dev/null
+++ b/osm_mon/evaluator/backends/prometheus.py
@@ -0,0 +1,61 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2018 Whitestack, LLC
+# *************************************************************
+
+# This file is part of OSM Monitoring module
+# All Rights Reserved to Whitestack, LLC
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+
+#         http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: bdiaz@whitestack.com or glavado@whitestack.com
+##
+import logging
+
+import requests
+
+from osm_mon.core.config import Config
+from osm_mon.evaluator.backends.base import BaseBackend
+
+log = logging.getLogger(__name__)
+
+OSM_METRIC_PREFIX = 'osm_'
+
+
+class PrometheusBackend(BaseBackend):
+
+    def __init__(self, config: Config):
+        super().__init__(config)
+        self.conf = config
+
+    def get_metric_value(self, metric_name, nsr_id, vdur_name, vnf_member_index):
+        query_section = "query={0}{{ns_id=\"{1}\",vdu_name=\"{2}\",vnf_member_index=\"{3}\"}}".format(
+            OSM_METRIC_PREFIX + metric_name, nsr_id, vdur_name, vnf_member_index)
+        request_url = self.conf.get('prometheus', 'url') + "/api/v1/query?" + query_section
+        log.info("Querying Prometheus: %s", request_url)
+        r = requests.get(request_url, timeout=int(self.conf.get('global', 'request_timeout')))
+        if r.status_code == 200:
+            json_response = r.json()
+            if json_response['status'] == 'success':
+                result = json_response['data']['result']
+                if len(result):
+                    metric_value = float(result[0]['value'][1])
+                    log.info("Metric value: %s", metric_value)
+                    return metric_value
+                else:
+                    return None
+            else:
+                log.warning("Prometheus response is not success. Got status %s", json_response['status'])
+        else:
+            log.warning("Error contacting Prometheus. Got status code %s: %s", r.status_code, r.text)
+        return None
diff --git a/osm_mon/evaluator/evaluator.py b/osm_mon/evaluator/evaluator.py
index 24e8e43..d3fdfd5 100644
--- a/osm_mon/evaluator/evaluator.py
+++ b/osm_mon/evaluator/evaluator.py
@@ -24,28 +24,18 @@
 import logging
 import multiprocessing
 import time
-from enum import Enum
 
 import peewee
-import requests
-from osm_common.dbbase import DbException
 
-from osm_mon.collector.backends.prometheus import OSM_METRIC_PREFIX
-from osm_mon.core.common_db import CommonDbClient
 from osm_mon.core.config import Config
-from osm_mon.core.database import DatabaseManager, Alarm
+from osm_mon.core.database import Alarm
 from osm_mon.core.message_bus_client import MessageBusClient
 from osm_mon.core.response import ResponseBuilder
+from osm_mon.evaluator.service import EvaluatorService, AlarmStatus
 
 log = logging.getLogger(__name__)
 
 
-class AlarmStatus(Enum):
-    ALARM = 'alarm'
-    OK = 'ok'
-    INSUFFICIENT = 'insufficient-data'
-
-
 class Evaluator:
 
     def __init__(self, config: Config, loop=None):
@@ -53,52 +43,9 @@
         if not loop:
             loop = asyncio.get_event_loop()
         self.loop = loop
-        self.common_db = CommonDbClient(self.conf)
-        self.plugins = []
-        self.database_manager = DatabaseManager(self.conf)
-        self.database_manager.create_tables()
-        self.queue = multiprocessing.Queue()
+        self.service = EvaluatorService(config)
         self.msg_bus = MessageBusClient(config)
 
-    def _evaluate_metric(self,
-                         nsr_id: str,
-                         vnf_member_index: int,
-                         vdur_name: str,
-                         metric_name: str,
-                         alarm: Alarm):
-        log.debug("_evaluate_metric")
-        # TODO: Refactor to fit backend plugin model
-        query_section = "query={0}{{ns_id=\"{1}\",vdu_name=\"{2}\",vnf_member_index=\"{3}\"}}".format(
-            OSM_METRIC_PREFIX + metric_name, nsr_id, vdur_name, vnf_member_index)
-        request_url = self.conf.get('prometheus', 'url') + "/api/v1/query?" + query_section
-        log.info("Querying Prometheus: %s", request_url)
-        r = requests.get(request_url, timeout=int(self.conf.get('global', 'request_timeout')))
-        if r.status_code == 200:
-            json_response = r.json()
-            if json_response['status'] == 'success':
-                result = json_response['data']['result']
-                if result:
-                    metric_value = float(result[0]['value'][1])
-                    log.info("Metric value: %s", metric_value)
-                    if alarm.operation.upper() == 'GT':
-                        if metric_value > alarm.threshold:
-                            self.queue.put((alarm, AlarmStatus.ALARM))
-                        else:
-                            self.queue.put((alarm, AlarmStatus.OK))
-                    elif alarm.operation.upper() == 'LT':
-                        if metric_value < alarm.threshold:
-                            self.queue.put((alarm, AlarmStatus.ALARM))
-                        else:
-                            self.queue.put((alarm, AlarmStatus.OK))
-                else:
-                    log.warning("No metric result for alarm %s", alarm.id)
-                    self.queue.put((alarm, AlarmStatus.INSUFFICIENT))
-
-            else:
-                log.warning("Prometheus response is not success. Got status %s", json_response['status'])
-        else:
-            log.warning("Error contacting Prometheus. Got status code %s: %s", r.status_code, r.text)
-
     def evaluate_forever(self):
         log.debug('evaluate_forever')
         while True:
@@ -113,65 +60,7 @@
 
     def evaluate(self):
         log.debug('evaluate')
-        processes = []
-        for alarm in Alarm.select():
-            try:
-                vnfr = self.common_db.get_vnfr(alarm.nsr_id, alarm.vnf_member_index)
-            except DbException:
-                log.exception("Error getting vnfr: ")
-                continue
-            vnfd = self.common_db.get_vnfd(vnfr['vnfd-id'])
-            try:
-                vdur = next(filter(lambda vdur: vdur['name'] == alarm.vdur_name, vnfr['vdur']))
-            except StopIteration:
-                log.warning("No vdur found with name %s for alarm %s", alarm.vdur_name, alarm.id)
-                continue
-            vdu = next(filter(lambda vdu: vdu['id'] == vdur['vdu-id-ref'], vnfd['vdu']))
-            vnf_monitoring_param = next(
-                filter(lambda param: param['id'] == alarm.monitoring_param, vnfd['monitoring-param']))
-            nsr_id = vnfr['nsr-id-ref']
-            vnf_member_index = vnfr['member-vnf-index-ref']
-            vdur_name = vdur['name']
-            if 'vdu-monitoring-param' in vnf_monitoring_param:
-                vdu_monitoring_param = next(filter(
-                    lambda param: param['id'] == vnf_monitoring_param['vdu-monitoring-param'][
-                        'vdu-monitoring-param-ref'], vdu['monitoring-param']))
-                nfvi_metric = vdu_monitoring_param['nfvi-metric']
-
-                p = multiprocessing.Process(target=self._evaluate_metric,
-                                            args=(nsr_id,
-                                                  vnf_member_index,
-                                                  vdur_name,
-                                                  nfvi_metric,
-                                                  alarm))
-                processes.append(p)
-                p.start()
-            if 'vdu-metric' in vnf_monitoring_param:
-                vnf_metric_name = vnf_monitoring_param['vdu-metric']['vdu-metric-name-ref']
-                p = multiprocessing.Process(target=self._evaluate_metric,
-                                            args=(nsr_id,
-                                                  vnf_member_index,
-                                                  vdur_name,
-                                                  vnf_metric_name,
-                                                  alarm))
-                processes.append(p)
-                p.start()
-            if 'vnf-metric' in vnf_monitoring_param:
-                vnf_metric_name = vnf_monitoring_param['vnf-metric']['vnf-metric-name-ref']
-                p = multiprocessing.Process(target=self._evaluate_metric,
-                                            args=(nsr_id,
-                                                  vnf_member_index,
-                                                  '',
-                                                  vnf_metric_name,
-                                                  alarm))
-                processes.append(p)
-                p.start()
-
-        for process in processes:
-            process.join(timeout=10)
-        alarms_tuples = []
-        while not self.queue.empty():
-            alarms_tuples.append(self.queue.get())
+        alarms_tuples = self.service.evaluate_alarms()
         for alarm, status in alarms_tuples:
             p = multiprocessing.Process(target=self.notify_alarm,
                                         args=(alarm, status))
diff --git a/osm_mon/evaluator/service.py b/osm_mon/evaluator/service.py
new file mode 100644
index 0000000..0868e32
--- /dev/null
+++ b/osm_mon/evaluator/service.py
@@ -0,0 +1,153 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2018 Whitestack, LLC
+# *************************************************************
+
+# This file is part of OSM Monitoring module
+# All Rights Reserved to Whitestack, LLC
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+
+#         http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: bdiaz@whitestack.com or glavado@whitestack.com
+##
+import logging
+import multiprocessing
+from enum import Enum
+from typing import Tuple, List
+
+from osm_common.dbbase import DbException
+
+from osm_mon.core import database
+from osm_mon.core.common_db import CommonDbClient
+from osm_mon.core.config import Config
+from osm_mon.core.database import Alarm, AlarmRepository
+from osm_mon.evaluator.backends.prometheus import PrometheusBackend
+
+log = logging.getLogger(__name__)
+
+BACKENDS = {
+    'prometheus': PrometheusBackend
+}
+
+
+class AlarmStatus(Enum):
+    ALARM = 'alarm'
+    OK = 'ok'
+    INSUFFICIENT = 'insufficient-data'
+
+
+class EvaluatorService:
+
+    def __init__(self, config: Config):
+        self.conf = config
+        self.common_db = CommonDbClient(self.conf)
+        self.queue = multiprocessing.Queue()
+
+    def _get_metric_value(self,
+                          nsr_id: str,
+                          vnf_member_index: int,
+                          vdur_name: str,
+                          metric_name: str):
+        return BACKENDS[self.conf.get('evaluator', 'backend')]().get_metric_value(metric_name, nsr_id, vdur_name,
+                                                                                  vnf_member_index)
+
+    def _evaluate_metric(self,
+                         nsr_id: str,
+                         vnf_member_index: int,
+                         vdur_name: str,
+                         metric_name: str,
+                         alarm: Alarm):
+        log.debug("_evaluate_metric")
+        metric_value = self._get_metric_value(nsr_id, vnf_member_index, vdur_name, metric_name)
+        if not metric_value:
+            log.warning("No metric result for alarm %s", alarm.id)
+            self.queue.put((alarm, AlarmStatus.INSUFFICIENT))
+        else:
+            if alarm.operation.upper() == 'GT':
+                if metric_value > alarm.threshold:
+                    self.queue.put((alarm, AlarmStatus.ALARM))
+                else:
+                    self.queue.put((alarm, AlarmStatus.OK))
+            elif alarm.operation.upper() == 'LT':
+                if metric_value < alarm.threshold:
+                    self.queue.put((alarm, AlarmStatus.ALARM))
+                else:
+                    self.queue.put((alarm, AlarmStatus.OK))
+
+    def evaluate_alarms(self) -> List[Tuple[Alarm, AlarmStatus]]:
+        log.debug('evaluate_alarms')
+        processes = []
+        database.db.connect()
+        try:
+            with database.db.atomic():
+                for alarm in AlarmRepository.list():
+                    try:
+                        vnfr = self.common_db.get_vnfr(alarm.nsr_id, alarm.vnf_member_index)
+                    except DbException:
+                        log.exception("Error getting vnfr: ")
+                        continue
+                    vnfd = self.common_db.get_vnfd(vnfr['vnfd-id'])
+                    try:
+                        vdur = next(filter(lambda vdur: vdur['name'] == alarm.vdur_name, vnfr['vdur']))
+                    except StopIteration:
+                        log.warning("No vdur found with name %s for alarm %s", alarm.vdur_name, alarm.id)
+                        continue
+                    vdu = next(filter(lambda vdu: vdu['id'] == vdur['vdu-id-ref'], vnfd['vdu']))
+                    vnf_monitoring_param = next(
+                        filter(lambda param: param['id'] == alarm.monitoring_param, vnfd['monitoring-param']))
+                    nsr_id = vnfr['nsr-id-ref']
+                    vnf_member_index = vnfr['member-vnf-index-ref']
+                    vdur_name = vdur['name']
+                    if 'vdu-monitoring-param' in vnf_monitoring_param:
+                        vdu_monitoring_param = next(filter(
+                            lambda param: param['id'] == vnf_monitoring_param['vdu-monitoring-param'][
+                                'vdu-monitoring-param-ref'], vdu['monitoring-param']))
+                        nfvi_metric = vdu_monitoring_param['nfvi-metric']
+
+                        p = multiprocessing.Process(target=self._evaluate_metric,
+                                                    args=(nsr_id,
+                                                          vnf_member_index,
+                                                          vdur_name,
+                                                          nfvi_metric,
+                                                          alarm))
+                        processes.append(p)
+                        p.start()
+                    if 'vdu-metric' in vnf_monitoring_param:
+                        vnf_metric_name = vnf_monitoring_param['vdu-metric']['vdu-metric-name-ref']
+                        p = multiprocessing.Process(target=self._evaluate_metric,
+                                                    args=(nsr_id,
+                                                          vnf_member_index,
+                                                          vdur_name,
+                                                          vnf_metric_name,
+                                                          alarm))
+                        processes.append(p)
+                        p.start()
+                    if 'vnf-metric' in vnf_monitoring_param:
+                        vnf_metric_name = vnf_monitoring_param['vnf-metric']['vnf-metric-name-ref']
+                        p = multiprocessing.Process(target=self._evaluate_metric,
+                                                    args=(nsr_id,
+                                                          vnf_member_index,
+                                                          '',
+                                                          vnf_metric_name,
+                                                          alarm))
+                        processes.append(p)
+                        p.start()
+
+                for process in processes:
+                    process.join(timeout=10)
+                alarms_tuples = []
+                while not self.queue.empty():
+                    alarms_tuples.append(self.queue.get())
+                return alarms_tuples
+        finally:
+            database.db.close()