Add external SNS topic trigger stack

src/aibs_informatics_cdk_lib/constructs_/external_sns_trigger.py

@@ -0,0 +1,128 @@
+from typing import Any, Mapping, Optional, Sequence, Union
+
+import aws_cdk as cdk
+import constructs
+from aibs_informatics_core.env import EnvBase, EnvType, ResourceNameBaseEnum
+from aws_cdk import aws_cloudwatch as cloudwatch
+from aws_cdk import aws_lambda as lambda_
+from aws_cdk import aws_sns as sns
+from aws_cdk import aws_sqs as sqs
+from aws_cdk.aws_lambda_event_sources import SqsEventSource
+from aws_cdk.aws_sns_subscriptions import SqsSubscription
+
+
+class ExternalSnsTrigger(constructs.Construct):
+    def __init__(
+        self,
+        scope: constructs.Construct,
+        id: str,
+        env_base: EnvBase,
+        triggered_lambda_fn: lambda_.Function,
+        external_sns_event_name: Union[str, ResourceNameBaseEnum],
+        external_sns_topic_arn: str,
+        external_sns_event_queue_filters: Optional[Sequence[Mapping[str, Any]]] = None,
+        **kwargs,
+    ) -> None:
+        """This intended to be a generic CDK construct that defines resources necessary to
+        implement a trigger system that listens for events from an external
+        (some other AWS account) SNS Topic and fires off a lambda in the
+        account where this stack is deployed.
+
+
+                              ┌---- ExternalSNSTrigger ----┐
+                              |                            |
+        (other AWS account)   |           (SQS)            |       (provided Lambda)
+        external_sns_topic -----> external_sns_event_queue -----> triggered_lambda_fn
+                              |             |              |
+                              |             v              |
+                              |         (SQS DLQ)          |
+                              |   external_sns_event_dlq   |
+                              |             |              |
+                              |             v              |
+                              |        (Cloudwatch)        |
+                              | triggered_lambda_dlq_alarm |
+                              |                            |
+                              └----------------------------┘
+
+        The main intended use case is to provide a simple template for setting up automation
+        based on PTS SNS Topic notifications in a separate AWS account (e.g. in an informatics processing pipeline)
+
+        Example usage:
+        self.external_sns_trigger_construct = ExternalSnsTrigger(
+            scope=self,
+            id=self.env_base.get_construct_id("merscope-imaging-process-sns-trigger"),
+            env_base=self.env_base,
+            triggered_lambda_fn=self.pts_listener_fn,
+            external_sns_event_name="merscope-imaging-process",
+            external_sns_topic_arn=f"arn:aws:sns:us-west-2:{account_id}:{sns_topic_name}",
+        )
+        """
+        super().__init__(scope=scope, id=id)
+
+        external_sns_event_dlq_name = env_base.prefixed(external_sns_event_name, "sns-event-dlq")
+        self.external_sns_event_dlq = sqs.Queue(
+            scope=self,
+            id=env_base.get_construct_id(external_sns_event_name, "sns-event-dlq"),
+            queue_name=external_sns_event_dlq_name,
+            retention_period=cdk.Duration.days(14),
+        )
+
+        self.external_sns_event_queue = sqs.Queue(
+            scope=self,
+            id=env_base.get_construct_id(external_sns_event_name, "sns-event-queue"),
+            queue_name=env_base.prefixed(external_sns_event_name, "sns-event-queue"),
+            retention_period=cdk.Duration.days(7),
+            dead_letter_queue=sqs.DeadLetterQueue(
+                max_receive_count=2,
+                queue=self.external_sns_event_dlq,
+            ),
+            # visibility_timeout must be longer than the `timeout` of the `triggered_lambda_fn` or deploy will fail
+            visibility_timeout=cdk.Duration.seconds(330),
+        )
+
+        # The *owning* AWS account of the SNS topic needs to give Subscribe permissions to the
+        # AWS account where this stack will be deployed
+        # See: https://docs.aws.amazon.com/sns/latest/dg/sns-send-message-to-sqs-cross-account.html
+        self.external_sns_topic = sns.Topic.from_topic_arn(
+            scope=self,
+            id=env_base.get_construct_id(external_sns_event_name, "external-sns-topic"),
+            topic_arn=external_sns_topic_arn,
+        )
+
+        # Useful reference:
+        # https://docs.aws.amazon.com/cdk/api/v2/python/aws_cdk.aws_sns/Subscription.html#aws_cdk.aws_sns.Subscription
+        self.external_sns_topic.add_subscription(
+            SqsSubscription(
+                queue=self.external_sns_event_queue,
+                raw_message_delivery=True,
+            )
+        )
+
+        triggered_lambda_fn.add_event_source(
+            source=SqsEventSource(
+                queue=self.external_sns_event_queue,
+                report_batch_item_failures=True,
+                filters=external_sns_event_queue_filters,
+                enabled=(env_base.env_type is EnvType.PROD),
+            )
+        )
+        self.external_sns_event_queue.grant_consume_messages(triggered_lambda_fn)
+
+        # Alarm that fires if external_sns_event_queue fails delivery or if lambda fails to process
+        # Further actions can be configured by accessing ExternalSnsTrigger.triggered_lambda_dlq_alarm resource
+        # TODO: Revisit making alarms even more configurable in the future
+        self.triggered_lambda_dlq_alarm = cloudwatch.Alarm(
+            scope=self,
+            id=env_base.get_construct_id(external_sns_event_name, "sns-event-dlq-alarm"),
+            alarm_description=(
+                f"Alarm if more than 1 message in {external_sns_event_dlq_name} in 10 minute period"
+            ),
+            metric=self.external_sns_event_dlq.metric_approximate_number_of_messages_visible(
+                statistic=cloudwatch.Stats.MAXIMUM,
+                period=cdk.Duration.minutes(10),
+            ),
+            evaluation_periods=1,
+            threshold=1,
+            datapoints_to_alarm=1,
+            comparison_operator=cloudwatch.ComparisonOperator.GREATER_THAN_OR_EQUAL_TO_THRESHOLD,
+        )