1 files changed, 158 insertions, 0 deletions
diff --git a/components/pm-subscription-handler/pmsh_service/mod/pmsh_config.py b/components/pm-subscription-handler/pmsh_service/mod/pmsh_config.py
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+++ b/components/pm-subscription-handler/pmsh_service/mod/pmsh_config.py
@@ -0,0 +1,158 @@
+# ============LICENSE_START===================================================
+#  Copyright (C) 2021 Nordix Foundation.
+# ============================================================================
+# 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.
+#
+# SPDX-License-Identifier: Apache-2.0
+# ============LICENSE_END=====================================================
+
+"""This module represents PMSH application configuration
+   Singleton instance of configuration is created and stored,
+   Enum representation is used for Message Router topics.
+"""
+
+from enum import Enum, unique
+
+import requests
+from onap_dcae_cbs_docker_client.client import get_all
+from requests.auth import HTTPBasicAuth
+from tenacity import wait_fixed, stop_after_attempt, retry, retry_if_exception_type
+
+from mod import logger
+from mod.pmsh_utils import mdc_handler
+
+
+@unique
+class MRTopic(Enum):
+    """ Enum used to represent Message Router Topic"""
+    AAI_SUBSCRIBER = 'aai_subscriber'
+    POLICY_PM_PUBLISHER = 'policy_pm_publisher'
+    POLICY_PM_SUBSCRIBER = 'policy_pm_subscriber'
+
+
+class MetaSingleton(type):
+    """ Metaclass used to create singleton object by overriding __call__() method """
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super().__call__(*args, **kwargs)
+        return cls._instances[cls]
+
+    @classmethod
+    def get_cls_instance(mcs, cls_name):
+        return mcs._instances[cls_name]
+
+
+class AppConfig(metaclass=MetaSingleton):
+    """ Object representation of the PMSH Application config. """
+
+    def __init__(self):
+        app_config = self._get_config()
+        self.key_path = app_config['config'].get('key_path')
+        self.cert_path = app_config['config'].get('cert_path')
+        self.ca_cert_path = app_config['config'].get('ca_cert_path')
+        self.enable_tls = app_config['config'].get('enable_tls')
+        self.aaf_id = app_config['config'].get('aaf_identity')
+        self.aaf_pass = app_config['config'].get('aaf_password')
+        self.streams_publishes = app_config['config'].get('streams_publishes')
+        self.streams_subscribes = app_config['config'].get('streams_subscribes')
+        # TODO: aaf_creds variable should be removed on code cleanup
+        self.aaf_creds = {'aaf_id': self.aaf_id, 'aaf_pass': self.aaf_pass}
+
+    @staticmethod
+    def get_instance():
+        return AppConfig.get_cls_instance(AppConfig)
+
+    @retry(wait=wait_fixed(5), stop=stop_after_attempt(5),
+           retry=retry_if_exception_type(ValueError))
+    def _get_config(self):
+
+        """ Retrieves PMSH's configuration from Config binding service. If a non-2xx response
+        is received, it retries after 2 seconds for 5 times before raising an exception.
+
+        Returns:
+            dict: Dictionary representation of the the service configuration
+
+        Raises:
+            Exception: If any error occurred pulling configuration from Config binding service.
+        """
+        try:
+            logger.info('Attempting to fetch PMSH Configuration from CBS.')
+            config = get_all()
+            logger.info(f'Successfully fetched PMSH config from CBS: {config}')
+            return config
+        except Exception as e:
+            logger.error(f'Failed to get config from CBS: {e}', exc_info=True)
+            raise ValueError(e)
+
+    @mdc_handler
+    def publish_to_topic(self, mr_topic, event_json, **kwargs):
+        """
+        Publish the event to the DMaaP Message Router topic.
+
+        Args:
+            mr_topic (enum) : Message Router topic to publish.
+            event_json (dict): the json data to be published.
+
+        Raises:
+            Exception: if post request fails.
+        """
+        try:
+            session = requests.Session()
+            topic_url = self.streams_publishes[mr_topic].get('dmaap_info').get('topic_url')
+            headers = {'content-type': 'application/json', 'x-transactionid': kwargs['request_id'],
+                       'InvocationID': kwargs['invocation_id'], 'RequestID': kwargs['request_id']}
+            logger.info(f'Publishing event to MR topic: {topic_url}')
+            response = session.post(topic_url, headers=headers,
+                                    auth=HTTPBasicAuth(self.aaf_id, self.aaf_pass), json=event_json,
+                                    verify=(self.ca_cert_path if self.enable_tls else False))
+            response.raise_for_status()
+        except Exception as e:
+            raise e
+
+    @mdc_handler
+    def get_from_topic(self, mr_topic, consumer_id, consumer_group='dcae_pmsh_cg', timeout=5000,
+                       **kwargs):
+        """
+        Returns the json data from the MrTopic.
+
+        Args:
+            mr_topic (enum) : Message Router topic to subscribe.
+            consumer_id (str): Within your subscribers group, a name that uniquely
+            identifies your subscribers process.
+            consumer_group (str): A name that uniquely identifies your subscribers.
+            timeout (int): The request timeout value in mSec.
+
+        Returns:
+            list[str]: the json response from DMaaP Message Router topic.
+        """
+        try:
+            session = requests.Session()
+            topic_url = self.streams_subscribes[mr_topic].get('dmaap_info').get('topic_url')
+            headers = {'accept': 'application/json', 'content-type': 'application/json',
+                       'InvocationID': kwargs['invocation_id'], 'RequestID': kwargs['request_id']}
+            logger.info(f'Fetching messages from MR topic: {topic_url}')
+            response = session.get(f'{topic_url}/{consumer_group}/{consumer_id}'
+                                   f'?timeout={timeout}',
+                                   auth=HTTPBasicAuth(self.aaf_id, self.aaf_pass), headers=headers,
+                                   verify=(self.ca_cert_path if self.enable_tls else False))
+            if response.status_code == 503:
+                logger.error(f'MR Service is unavailable at present: {response.content}')
+                pass
+            response.raise_for_status()
+            if response.ok:
+                return response.json()
+        except Exception as e:
+            logger.error(f'Failed to fetch message from MR: {e}', exc_info=True)
+            raise