From dbfa456dda04f995479c995a361b60f521e1753e Mon Sep 17 00:00:00 2001
From: Oran Avraham <252748+oranav@users.noreply.github.com>
Date: Sun, 25 Feb 2024 23:20:32 +0200
Subject: [PATCH] RDS: Allow copying snapshots of deleted DB instances (#7392)

---
 moto/rds/models.py         | 14 +++++++++-----
 tests/test_rds/test_rds.py |  7 ++++++-
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/moto/rds/models.py b/moto/rds/models.py
index 18ffab32f..ace7eaf05 100644
--- a/moto/rds/models.py
+++ b/moto/rds/models.py
@@ -1782,14 +1782,18 @@ class RDSBackend(BaseBackend):
 
     def create_db_snapshot(
         self,
-        db_instance_identifier: str,
+        db_instance: Union[str, Database],
         db_snapshot_identifier: str,
         snapshot_type: str = "manual",
         tags: Optional[List[Dict[str, str]]] = None,
     ) -> DatabaseSnapshot:
-        database = self.databases.get(db_instance_identifier)
-        if not database:
-            raise DBInstanceNotFoundError(db_instance_identifier)
+        if isinstance(db_instance, str):
+            database = self.databases.get(db_instance)
+            if not database:
+                raise DBInstanceNotFoundError(db_instance)
+        else:
+            database = db_instance
+
         if db_snapshot_identifier in self.database_snapshots:
             raise DBSnapshotAlreadyExistsError(db_snapshot_identifier)
         if len(self.database_snapshots) >= int(
@@ -1821,7 +1825,7 @@ class RDSBackend(BaseBackend):
         else:
             tags = self._merge_tags(source_snapshot.tags, tags)
         return self.create_db_snapshot(
-            db_instance_identifier=source_snapshot.database.db_instance_identifier,  # type: ignore
+            db_instance=source_snapshot.database,
             db_snapshot_identifier=target_snapshot_identifier,
             tags=tags,
         )
diff --git a/tests/test_rds/test_rds.py b/tests/test_rds/test_rds.py
index 4f0aa02ae..bf06b5645 100644
--- a/tests/test_rds/test_rds.py
+++ b/tests/test_rds/test_rds.py
@@ -1039,8 +1039,9 @@ def test_create_db_snapshots_with_tags():
     ]
 
 
+@pytest.mark.parametrize("delete_db_instance", [True, False])
 @mock_aws
-def test_copy_db_snapshots():
+def test_copy_db_snapshots(delete_db_instance: bool):
     conn = boto3.client("rds", region_name=DEFAULT_REGION)
 
     conn.create_db_instance(
@@ -1059,6 +1060,10 @@ def test_copy_db_snapshots():
         DBInstanceIdentifier="db-primary-1", DBSnapshotIdentifier="snapshot-1"
     ).get("DBSnapshot")
 
+    if delete_db_instance:
+        # Delete the original instance, but the copy snapshot operation should still succeed.
+        conn.delete_db_instance(DBInstanceIdentifier="db-primary-1")
+
     target_snapshot = conn.copy_db_snapshot(
         SourceDBSnapshotIdentifier="snapshot-1", TargetDBSnapshotIdentifier="snapshot-2"
     ).get("DBSnapshot")