From 3f948aa5ae3bbac1d0fa5efd82d79bde8b10f820 Mon Sep 17 00:00:00 2001
From: mattBrzezinski <matt.brzezinski@invenia.ca>
Date: Fri, 6 May 2022 12:11:55 -0500
Subject: [PATCH] RDS Filtering on db-cluster-id (#5101)

---
 moto/rds/models.py             |  5 ++++-
 moto/rds/responses.py          |  1 +
 tests/test_rds/test_filters.py | 16 ++++++++++++++--
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/moto/rds/models.py b/moto/rds/models.py
index f15287337..c6029b4b8 100644
--- a/moto/rds/models.py
+++ b/moto/rds/models.py
@@ -307,7 +307,7 @@ class ClusterSnapshot(BaseModel):
 class Database(CloudFormationModel):
 
     SUPPORTED_FILTERS = {
-        "db-cluster-id": FilterDef(None, "DB Cluster Identifiers"),
+        "db-cluster-id": FilterDef(["db_cluster_identifier"], "DB Cluster Identifiers"),
         "db-instance-id": FilterDef(
             ["db_instance_arn", "db_instance_identifier"], "DB Instance Identifiers"
         ),
@@ -357,6 +357,7 @@ class Database(CloudFormationModel):
             self.allocated_storage = Database.default_allocated_storage(
                 engine=self.engine, storage_type=self.storage_type
             )
+        self.db_cluster_identifier = kwargs.get("db_cluster_identifier")
         self.db_instance_identifier = kwargs.get("db_instance_identifier")
         self.source_db_identifier = kwargs.get("source_db_identifier")
         self.db_instance_class = kwargs.get("db_instance_class")
@@ -494,6 +495,7 @@ class Database(CloudFormationModel):
                 </VpcSecurityGroupMembership>
                 {% endfor %}
               </VpcSecurityGroups>
+              <DBClusterIdentifier>{{ database.db_cluster_identifier }}</DBClusterIdentifier>
               <DBInstanceIdentifier>{{ database.db_instance_identifier }}</DBInstanceIdentifier>
               <DbiResourceId>{{ database.dbi_resource_id }}</DbiResourceId>
               <InstanceCreateTime>{{ database.instance_create_time }}</InstanceCreateTime>
@@ -740,6 +742,7 @@ class Database(CloudFormationModel):
         "BackupRetentionPeriod": "{{ database.backup_retention_period }}",
         "CharacterSetName": {%- if database.character_set_name -%}{{ database.character_set_name }}{%- else %} null{%- endif -%},
         "DBInstanceClass": "{{ database.db_instance_class }}",
+        "DBClusterIdentifier": "{{ database.db_cluster_identifier }}",
         "DBInstanceIdentifier": "{{ database.db_instance_identifier }}",
         "DBInstanceStatus": "{{ database.status }}",
         "DBName": {%- if database.db_name -%}"{{ database.db_name }}"{%- else %} null{%- endif -%},
diff --git a/moto/rds/responses.py b/moto/rds/responses.py
index 3afa4824e..c2b7b9bac 100644
--- a/moto/rds/responses.py
+++ b/moto/rds/responses.py
@@ -19,6 +19,7 @@ class RDSResponse(BaseResponse):
             "backup_retention_period": self._get_param("BackupRetentionPeriod"),
             "copy_tags_to_snapshot": self._get_param("CopyTagsToSnapshot"),
             "db_instance_class": self._get_param("DBInstanceClass"),
+            "db_cluster_identifier": self._get_param("DBClusterIdentifier"),
             "db_instance_identifier": self._get_param("DBInstanceIdentifier"),
             "db_name": self._get_param("DBName"),
             "db_parameter_group_name": self._get_param("DBParameterGroupName"),
diff --git a/tests/test_rds/test_filters.py b/tests/test_rds/test_filters.py
index 87fac8f40..81e8e46ad 100644
--- a/tests/test_rds/test_filters.py
+++ b/tests/test_rds/test_filters.py
@@ -15,10 +15,12 @@ class TestDBInstanceFilters(object):
         cls.mock.start()
         client = boto3.client("rds", region_name="us-west-2")
         for i in range(10):
-            identifier = "db-instance-{}".format(i)
+            instance_identifier = "db-instance-{}".format(i)
+            cluster_identifier = "db-cluster-{}".format(i)
             engine = "postgres" if (i % 3) else "mysql"
             client.create_db_instance(
-                DBInstanceIdentifier=identifier,
+                DBInstanceIdentifier=instance_identifier,
+                DBClusterIdentifier=cluster_identifier,
                 Engine=engine,
                 DBInstanceClass="db.m1.small",
             )
@@ -49,6 +51,16 @@ class TestDBInstanceFilters(object):
         ex.value.response["Error"]["Code"].should.equal("InvalidParameterCombination")
         ex.value.response["Error"]["Message"].should.contain("must not be empty")
 
+    def test_db_cluster_id_filter(self):
+        resp = self.client.describe_db_instances()
+        db_cluster_identifier = resp["DBInstances"][0]["DBClusterIdentifier"]
+
+        db_instances = self.client.describe_db_instances(
+            Filters=[{"Name": "db-cluster-id", "Values": [db_cluster_identifier]}]
+        ).get("DBInstances")
+        db_instances.should.have.length_of(1)
+        db_instances[0]["DBClusterIdentifier"].should.equal(db_cluster_identifier)
+
     def test_db_instance_id_filter(self):
         resp = self.client.describe_db_instances()
         db_instance_identifier = resp["DBInstances"][0]["DBInstanceIdentifier"]