Reference data event bus through SSM parameter

landonshumway-ia · landonshumway-ia · commit 3dc22954fd78 · 2025-04-12T00:46:54.000-05:00
diff --git a/backend/compact-connect/common_constructs/ssm_parameter_utility.py b/backend/compact-connect/common_constructs/ssm_parameter_utility.py
@@ -0,0 +1,37 @@
+from aws_cdk.aws_events import EventBus
+from aws_cdk.aws_ssm import StringParameter
+from constructs import Construct
+
+DATA_EVENT_BUS_ARN_SSM_PARAMETER_NAME = '/deployment/event-bridge/event-bus/data-event-bus-arn'
+
+
+class SSMParameterUtility:
+    """
+    Utility class for SSM parameter operations.
+
+    This class provides static methods for common SSM parameter operations,
+    such as loading resources from SSM parameters to bypass cross-stack references.
+    """
+
+    @staticmethod
+    def load_data_event_bus_from_ssm_parameter(scope: Construct) -> EventBus:
+        """
+        Load the data event bus from an SSM parameter.
+
+        This pattern breaks cross-stack references by storing and retrieving
+        the event bus ARN in SSM Parameter Store rather than using a direct reference,
+        which helps avoid issues with CloudFormation stack updates.
+
+        Args:
+            scope: The CDK construct scope
+
+        Returns:
+            The EventBus construct
+        """
+        data_event_bus_arn = StringParameter.from_string_parameter_name(
+            scope,
+            'DataEventBusArnParameter',
+            string_parameter_name=DATA_EVENT_BUS_ARN_SSM_PARAMETER_NAME,
+        )
+
+        return EventBus.from_event_bus_arn(scope, 'DataEventBus', event_bus_arn=data_event_bus_arn.string_value)
diff --git a/backend/compact-connect/stacks/api_stack/v1_api/query_providers.py b/backend/compact-connect/stacks/api_stack/v1_api/query_providers.py
@@ -19,6 +19,7 @@
 from cdk_nag import NagSuppressions
 from common_constructs.nodejs_function import NodejsFunction
 from common_constructs.python_function import PythonFunction
+from common_constructs.ssm_parameter_utility import SSMParameterUtility
 from common_constructs.stack import Stack
 
 from stacks import persistent_stack as ps
@@ -48,13 +49,17 @@ def __init__(
         self.api_model = api_model
 
         stack: Stack = Stack.of(resource)
+
+        # Load the data event bus from SSM parameter instead of direct reference
+        data_event_bus = SSMParameterUtility.load_data_event_bus_from_ssm_parameter(stack)
+
         lambda_environment = {
             'PROVIDER_TABLE_NAME': persistent_stack.provider_table.table_name,
             'PROV_FAM_GIV_MID_INDEX_NAME': persistent_stack.provider_table.provider_fam_giv_mid_index_name,
             'PROV_DATE_OF_UPDATE_INDEX_NAME': persistent_stack.provider_table.provider_date_of_update_index_name,
             'SSN_TABLE_NAME': persistent_stack.ssn_table.table_name,
             'SSN_INDEX_NAME': persistent_stack.ssn_table.ssn_index_name,
-            'EVENT_BUS_NAME': persistent_stack.data_event_bus.event_bus_name,
+            'EVENT_BUS_NAME': data_event_bus.event_bus_name,
             'RATE_LIMITING_TABLE_NAME': persistent_stack.rate_limiting_table.table_name,
             'USER_POOL_ID': persistent_stack.staff_users.user_pool_id,
             'EMAIL_NOTIFICATION_SERVICE_LAMBDA_NAME': persistent_stack.email_notification_service_lambda.function_name,
@@ -85,7 +90,7 @@ def __init__(
         self._add_deactivate_privilege(
             method_options=admin_method_options,
             provider_data_table=persistent_stack.provider_table,
-            event_bus=persistent_stack.data_event_bus,
+            event_bus=data_event_bus,
             email_service_lambda=persistent_stack.email_notification_service_lambda,
             staff_users_table=persistent_stack.staff_users.user_table,
             lambda_environment=lambda_environment,
diff --git a/backend/compact-connect/stacks/ingest_stack.py b/backend/compact-connect/stacks/ingest_stack.py
@@ -5,11 +5,12 @@
 from aws_cdk import Duration
 from aws_cdk.aws_cloudwatch import Alarm, ComparisonOperator, Metric, Stats, TreatMissingData
 from aws_cdk.aws_cloudwatch_actions import SnsAction
-from aws_cdk.aws_events import EventPattern, Rule
+from aws_cdk.aws_events import EventBus, EventPattern, Rule
 from aws_cdk.aws_events_targets import SqsQueue
 from cdk_nag import NagSuppressions
 from common_constructs.python_function import PythonFunction
 from common_constructs.queued_lambda_processor import QueuedLambdaProcessor
+from common_constructs.ssm_parameter_utility import SSMParameterUtility
 from common_constructs.stack import AppStack, Stack
 from constructs import Construct
 
@@ -27,9 +28,11 @@ def __init__(
         **kwargs,
     ):
         super().__init__(scope, construct_id, environment_name=environment_name, **kwargs)
-        self._add_v1_ingest_chain(persistent_stack)
+        # We explicitly get the event bus arn from parameter store, to avoid issues with cross stack updates
+        data_event_bus = SSMParameterUtility.load_data_event_bus_from_ssm_parameter(self)
+        self._add_v1_ingest_chain(persistent_stack, data_event_bus)
 
-    def _add_v1_ingest_chain(self, persistent_stack: ps.PersistentStack):
+    def _add_v1_ingest_chain(self, persistent_stack: ps.PersistentStack, data_event_bus: EventBus):
         ingest_handler = PythonFunction(
             self,
             'V1IngestHandler',
@@ -39,14 +42,14 @@ def _add_v1_ingest_chain(self, persistent_stack: ps.PersistentStack):
             handler='ingest_license_message',
             timeout=Duration.minutes(1),
             environment={
-                'EVENT_BUS_NAME': persistent_stack.data_event_bus.event_bus_name,
+                'EVENT_BUS_NAME': data_event_bus.event_bus_name,
                 'PROVIDER_TABLE_NAME': persistent_stack.provider_table.table_name,
                 **self.common_env_vars,
             },
             alarm_topic=persistent_stack.alarm_topic,
         )
         persistent_stack.provider_table.grant_read_write_data(ingest_handler)
-        persistent_stack.data_event_bus.grant_put_events_to(ingest_handler)
+        data_event_bus.grant_put_events_to(ingest_handler)
 
         NagSuppressions.add_resource_suppressions_by_path(
             Stack.of(ingest_handler.role),
@@ -90,7 +93,7 @@ def _add_v1_ingest_chain(self, persistent_stack: ps.PersistentStack):
         ingest_rule = Rule(
             self,
             'V1IngestEventRule',
-            event_bus=persistent_stack.data_event_bus,
+            event_bus=data_event_bus,
             event_pattern=EventPattern(detail_type=['license.ingest']),
             targets=[SqsQueue(processor.queue, dead_letter_queue=processor.dlq)],
         )
@@ -103,7 +106,7 @@ def _add_v1_ingest_chain(self, persistent_stack: ps.PersistentStack):
                 namespace='AWS/Events',
                 metric_name='FailedInvocations',
                 dimensions_map={
-                    'EventBusName': persistent_stack.data_event_bus.event_bus_name,
+                    'EventBusName': data_event_bus.event_bus_name,
                     'RuleName': ingest_rule.rule_name,
                 },
                 period=Duration.minutes(5),
diff --git a/backend/compact-connect/stacks/persistent_stack/__init__.py b/backend/compact-connect/stacks/persistent_stack/__init__.py
@@ -15,6 +15,7 @@
 from common_constructs.nodejs_function import NodejsFunction
 from common_constructs.python_function import COMMON_PYTHON_LAMBDA_LAYER_SSM_PARAMETER_NAME
 from common_constructs.security_profile import SecurityProfile
+from common_constructs.ssm_parameter_utility import DATA_EVENT_BUS_ARN_SSM_PARAMETER_NAME
 from common_constructs.stack import AppStack
 from constructs import Construct
 
@@ -106,7 +107,21 @@ def __init__(
             auto_delete_objects=removal_policy == RemovalPolicy.DESTROY,
         )
 
-        self.data_event_bus = EventBus(self, 'DataEventBus')
+        # This resource should not be reference directly as a cross stack reference, any reference should
+        # be made through the SSM parameter
+        self._data_event_bus = EventBus( self, 'DataEventBus')
+        # We Store the data event bus name in SSM Parameter Store
+        # to avoid issues with cross stack references due to the fact that
+        # you can't update a CloudFormation exported value that is being referenced by a resource in another stack.
+        self.data_event_bus_arn_ssm_parameter = aws_ssm.StringParameter(
+            self,
+            'DataEventBusArnParameter',
+            parameter_name=DATA_EVENT_BUS_ARN_SSM_PARAMETER_NAME,
+            string_value=self._data_event_bus.event_bus_arn,
+        )
+        # TODO - these are needed until pipeline migration effort is complete  # noqa: FIX002
+        self.export_value(self._data_event_bus.event_bus_arn)
+        self.export_value(self._data_event_bus.event_bus_name)
 
         self._add_data_resources(removal_policy=removal_policy)
         self._add_migrations()
@@ -243,7 +258,7 @@ def _add_data_resources(self, removal_policy: RemovalPolicy):
             self,
             'SSNTable',
             removal_policy=removal_policy,
-            data_event_bus=self.data_event_bus,
+            data_event_bus=self._data_event_bus,
             alarm_topic=self.alarm_topic,
         )
 
@@ -257,7 +272,7 @@ def _add_data_resources(self, removal_policy: RemovalPolicy):
             bucket_encryption_key=self.ssn_table.key,
             removal_policy=removal_policy,
             auto_delete_objects=removal_policy == RemovalPolicy.DESTROY,
-            event_bus=self.data_event_bus,
+            event_bus=self._data_event_bus,
             license_preprocessing_queue=self.ssn_table.preprocessor_queue.queue,
             license_upload_role=self.ssn_table.license_upload_role,
         )
@@ -304,7 +319,7 @@ def _add_data_resources(self, removal_policy: RemovalPolicy):
             scope=self,
             construct_id='DataEventTable',
             encryption_key=self.shared_encryption_key,
-            event_bus=self.data_event_bus,
+            event_bus=self._data_event_bus,
             alarm_topic=self.alarm_topic,
             removal_policy=removal_policy,
         )
diff --git a/backend/compact-connect/stacks/persistent_stack/data_event_table.py b/backend/compact-connect/stacks/persistent_stack/data_event_table.py
@@ -116,7 +116,7 @@ def __init__(
                 namespace='AWS/Events',
                 metric_name='FailedInvocations',
                 dimensions_map={
-                    'EventBusName': stack.data_event_bus.event_bus_name,
+                    'EventBusName': event_bus.event_bus_name,
                     'RuleName': event_receiver_rule.rule_name,
                 },
                 period=Duration.minutes(5),
diff --git a/backend/compact-connect/tests/app/base.py b/backend/compact-connect/tests/app/base.py
@@ -212,7 +212,7 @@ def _inspect_ssn_table(self, persistent_stack: PersistentStack, persistent_stack
 
     def _inspect_data_events_table(self, persistent_stack: PersistentStack, persistent_stack_template: Template):
         # Ensure our DataEventTable and queues are created
-        event_bus_logical_id = persistent_stack.get_logical_id(persistent_stack.data_event_bus.node.default_child)
+        event_bus_logical_id = persistent_stack.get_logical_id(persistent_stack._data_event_bus.node.default_child)  # noqa: SLF001 private_member_access
         queue_logical_id = persistent_stack.get_logical_id(
             persistent_stack.data_event_table.event_processor.queue.node.default_child
         )

Original file line number	Diff line number	Diff line change
`@@ -212,7 +212,7 @@ def _inspect_ssn_table(self, persistent_stack: PersistentStack, persistent_stack`
`212`	`212`
`213`	`213`	`def _inspect_data_events_table(self, persistent_stack: PersistentStack, persistent_stack_template: Template):`
`214`	`214`	`# Ensure our DataEventTable and queues are created`
`215`		`- event_bus_logical_id = persistent_stack.get_logical_id(persistent_stack.data_event_bus.node.default_child)`
	`215`	`+ event_bus_logical_id = persistent_stack.get_logical_id(persistent_stack._data_event_bus.node.default_child) # noqa: SLF001 private_member_access`
`216`	`216`	`queue_logical_id = persistent_stack.get_logical_id(`
`217`	`217`	`persistent_stack.data_event_table.event_processor.queue.node.default_child`
`218`	`218`	`)`