[GitHub] [airflow] VijayantSoni commented on a change in pull request #8701: Adding ElastiCache Hook for creating, describing and deleting replication groups

[GitBox <gi...@apache.org>]

VijayantSoni commented on a change in pull request #8701:
URL: https://github.com/apache/airflow/pull/8701#discussion_r426907487



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File path: airflow/providers/amazon/aws/hooks/elasticache.py
##########
@@ -0,0 +1,259 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+import re
+from time import sleep
+
+from airflow.exceptions import AirflowException
+from airflow.providers.amazon.aws.hooks.base_aws import AwsBaseHook
+
+
+class ElastiCacheHook(AwsBaseHook):
+    """
+    Interact with AWS ElastiCache
+    """
+
+    # Constants for ElastiCache describe API response keys
+    REPLICATION_GROUPS = 'ReplicationGroups'
+    REPLICATION_GROUP = 'ReplicationGroup'
+    STATUS = 'Status'
+
+    # Constants for ElastiCache delete API response messages
+    RESPONSE_NOT_VALID_STATE = 'not in a valid state to be deleted'
+    RESPONSE_DELETING_STATE = 'has status deleting which is not valid for deletion'
+    RESPONSE_MODIFYING_STATE = 'has status modifying which is not valid for deletion'
+
+    # Constants for ElastiCache replication group status
+    STATUS_CREATING = 'creating'
+    STATUS_AVAILABLE = 'available'
+    STATUS_DELETING = 'deleting'
+    STATUS_CREATE_FAILED = 'create-failed'
+
+    def __init__(
+        self, max_retries=10, exponential_back_off_factor=1, initial_poke_interval=60, *args, **kwargs
+    ):
+        """
+        :param max_retries: Max tries for checking availability of and deleting replication group
+        :param exponential_back_off_factor: Factor for deciding next sleep time
+        :param initial_poke_interval: Initial sleep time in seconds
+        """
+        self.max_retries = max_retries
+        self.exponential_back_off_factor = exponential_back_off_factor
+        self.initial_poke_interval = initial_poke_interval
+
+        super().__init__(client_type='elasticache', *args, **kwargs)
+
+    def create_replication_group(self, config):
+        """
+        Call ElastiCache API for creating a replication group
+        :param config: Python dictionary to use as config for creating replication group
+        :return: Response from ElastiCache create replication group API
+        """
+        return self.conn.create_replication_group(**config)
+
+    def delete_replication_group(self, replication_group_id):
+        """
+        Call ElastiCache API for deleting a replication group
+        :param replication_group_id: ID of replication group to delete
+        :return: Response from ElastiCache delete replication group API
+        """
+        return self.conn.delete_replication_group(ReplicationGroupId=replication_group_id)
+
+    def describe_replication_group(self, replication_group_id):
+        """
+        Call ElastiCache API for describing a replication group
+        :param replication_group_id: ID of replication group to describe
+        :return: Response from ElastiCache describe replication group API
+        """
+        return self.conn.describe_replication_groups(ReplicationGroupId=replication_group_id)
+
+    def get_replication_group_status(self, replication_group_id):
+        """
+        Get current status of replication group
+        :param replication_group_id: ID of replication group to check for status
+        :return: Current status of replication group
+        """
+        return self.describe_replication_group(replication_group_id)[self.REPLICATION_GROUPS][0][self.STATUS]
+
+    def is_replication_group_available(self, replication_group_id):
+        """
+        Helper for checking if replication is available or not
+        :param replication_group_id: ID of replication group to check for availability
+        :return: True if available else False
+        replication group
+        """
+        return self.get_replication_group_status(
+            replication_group_id=replication_group_id
+        ) == self.STATUS_AVAILABLE
+
+    def should_stop_poking(self, replication_group_id):
+        """
+        Helper for checking if we should stop poking replication group for availability or not
+        :param replication_group_id: ID of replication group to check
+        :return: Flag to check if availability check should be stopped or not and current status of
+        replication group
+        """
+        status = self.get_replication_group_status(replication_group_id=replication_group_id)
+
+        return status in (
+            self.STATUS_AVAILABLE,
+            self.STATUS_CREATE_FAILED,
+            self.STATUS_DELETING
+        ), status
+
+    def wait_for_availability(
+        self,
+        replication_group_id,
+        initial_sleep_time=None,
+        exponential_back_off_factor=None,
+        max_retries=None
+    ):
+        """
+        Check if replication is available or not by performing a describe over it
+        :param max_retries: Max tries for checking availability of replication group
+        :param exponential_back_off_factor: Factor for deciding next sleep time
+        :param initial_sleep_time: Initial sleep time in seconds
+        :param replication_group_id: ID of replication group to check for availability
+        :return: True if replication is available else False
+        """
+        sleep_time = initial_sleep_time or self.initial_poke_interval
+        exponential_back_off_factor = exponential_back_off_factor or self.exponential_back_off_factor
+        max_retries = max_retries or self.max_retries
+        num_retries = 0
+        status = self.STATUS_CREATE_FAILED
+
+        while num_retries < max_retries:
+            stop_poking, status = self.should_stop_poking(replication_group_id=replication_group_id)
+
+            self.log.info('Status : %s', status)
+
+            if stop_poking:
+                self.log.info('Received signal to stop poking. Current status : "%s"', status)
+                break
+
+            num_retries += 1
+
+            self.log.info('Poke retry: %s. Sleep time: %s. Sleeping...', num_retries, sleep_time)
+
+            sleep(sleep_time)
+
+            sleep_time = sleep_time * exponential_back_off_factor
+
+        if status != self.STATUS_AVAILABLE:
+            self.log.warning('Replication group is not available. Current status : "%s"', status)
+
+            return False
+
+        return True
+
+    def wait_for_deletion(
+        self,
+        replication_group_id,
+        initial_sleep_time=None,
+        exponential_back_off_factor=None,
+        max_retries=None
+    ):
+        """
+        Helper for deleting a replication group ensuring it is either deleted or can't be deleted
+        :param replication_group_id: ID of replication to delete
+        :param max_retries: Max tries for checking availability of replication group
+        :param exponential_back_off_factor: Factor for deciding next sleep time
+        :param initial_sleep_time: Initial sleep time in second
+        :return: Response from ElastiCache delete replication group API and flag to identify if deleted or not
+        """
+        response = None
+        deleted = False
+        sleep_time = initial_sleep_time or self.initial_poke_interval
+        exponential_back_off_factor = exponential_back_off_factor or self.exponential_back_off_factor
+        max_retries = max_retries or self.max_retries
+        num_retries = 0
+
+        while not deleted and num_retries < max_retries:
+            try:
+                response = self.delete_replication_group(replication_group_id=replication_group_id)
+
+                self.log.info('Replication group with ID : %s : is being deleted...', replication_group_id)
+
+            except self.conn.exceptions.ReplicationGroupNotFoundFault:
+                self.log.info("Replication group with ID : '%s' does not exist", replication_group_id)
+
+                deleted = True
+
+            except self.conn.exceptions.InvalidReplicationGroupStateFault as exp:
+                message = exp.response['Error']['Message']
+
+                self.log.info('Received message : %s', message)
+
+                if re.search(self.RESPONSE_NOT_VALID_STATE, message) \
+                        or re.search(self.RESPONSE_MODIFYING_STATE, message):
+
+                    self.log.info(
+                        'Replication group with ID : %s : is not in valid state to be deleted',
+                        replication_group_id
+                    )
+
+                elif re.search(self.RESPONSE_DELETING_STATE, message):
+                    self.log.info(

Review comment:
       Because we delete from any state but only `available`, hence I issued `delete` each time. I have changed it to get status first and then only issue a `delete` when status is `available`. 




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