localstack · simonrw · Jun 20, 2025 · Jun 20, 2025 · Jun 20, 2025 · Jun 20, 2025
@@ -7,6 +7,7 @@
 
 from typing_extensions import TypeVar
 
+from localstack.services.cloudformation.engine.validations import ValidationError
 from localstack.utils.strings import camel_to_snake_case
 
 T = TypeVar("T")
@@ -140,6 +141,14 @@ def __str__(self):
     def __repr__(self):
         return str(self)
 
+    def validate(self, template: NodeTemplate):
+        self._perform_validation(template)
+        for child in self.get_children():
+            child.validate(template)
+
+    def _perform_validation(self, template: NodeTemplate):
+        pass
+
 
 class ChangeSetNode(ChangeSetEntity, abc.ABC): ...
 
@@ -384,6 +393,31 @@ def __init__(
         self.intrinsic_function = intrinsic_function
         self.arguments = arguments
 
+    def _perform_validation(self, template: NodeTemplate):
+        validation_fn = getattr(
+            self, f"_perform_validation_{self.intrinsic_function.lower()}", None
+        )
+        if validation_fn:
+            validation_fn(template)
+
+    def _perform_validation_ref(self, template: NodeTemplate):
+        target = self.arguments.value
+        for parameter in template.parameters.parameters:
+            if target == parameter.name:
+                return
+
+        for condition in template.conditions.conditions:
+            if target == condition.name:
+                return
+
+        for resource in template.resources.resources:
+            if target == resource.name:
+                return
+
+        raise ValidationError(
+            f"Template format error: Unresolved resource dependencies [{target}] in the Resources block of the template"
+        )
+
 
 class NodeObject(ChangeSetNode):
     bindings: Final[dict[str, ChangeSetEntity]]

@@ -44,6 +44,7 @@
 from localstack.services.cloudformation.engine.v2.change_set_model_visitor import (
     ChangeSetModelVisitor,
 )
+from localstack.services.cloudformation.engine.validations import ValidationError
 from localstack.services.cloudformation.stores import get_cloudformation_store
 from localstack.services.cloudformation.v2.entities import ChangeSet
 from localstack.utils.aws.arns import get_partition
@@ -187,7 +188,7 @@ def _get_node_resource_for(
             if node_resource.name == resource_name:
                 self.visit(node_resource)
                 return node_resource
-        raise RuntimeError(f"No resource '{resource_name}' was found")
+        raise ValidationError(f"No resource '{resource_name}' was found")
 
     def _get_node_property_for(
         self, property_name: str, node_resource: NodeResource

@@ -0,0 +1,15 @@
+from localstack.services.cloudformation.engine.v2.change_set_model import ChangeSetEntity
+from localstack.services.cloudformation.engine.v2.change_set_model_preproc import (
+    ChangeSetModelPreproc,
+)
+
+
+class ChangeSetModelValidator(ChangeSetModelPreproc):
+    def validate(self):
+        self.visit(self._node_template)
+
+    def visit(self, change_set_entity: ChangeSetEntity):
+        scope = change_set_entity.scope
+        if scope in self._processed:
+            return
+        change_set_entity.validate(change_set_entity)
@@ -1,10 +1,11 @@
 from datetime import datetime, timezone
-from typing import Optional, TypedDict
+from typing import NotRequired, Optional, TypedDict
 
 from localstack.aws.api.cloudformation import (
     ChangeSetStatus,
     ChangeSetType,
     CreateChangeSetInput,
+    CreateStackInput,
     ExecutionStatus,
     Output,
     Parameter,
@@ -21,7 +22,6 @@
 )
 from localstack.services.cloudformation.engine.entities import (
     StackIdentifier,
-    StackTemplate,
 )
 from localstack.services.cloudformation.engine.v2.change_set_model import (
     NodeTemplate,
@@ -38,7 +38,6 @@ class Stack:
     stack_name: str
     parameters: list[Parameter]
     change_set_id: str | None
-    change_set_name: str | None
     status: StackStatus
     status_reason: StackStatusReason | None
     stack_id: str
@@ -56,23 +55,22 @@ def __init__(
         self,
         account_id: str,
         region_name: str,
-        request_payload: CreateChangeSetInput,
-        template: StackTemplate | None = None,
+        request_payload: CreateChangeSetInput | CreateStackInput,
+        template: dict | None = None,
         template_body: str | None = None,
-        change_set_ids: list[str] | None = None,
     ):
         self.account_id = account_id
         self.region_name = region_name
         self.template = template
         self.template_body = template_body
         self.status = StackStatus.CREATE_IN_PROGRESS
         self.status_reason = None
-        self.change_set_ids = change_set_ids or []
+        self.change_set_ids = []
         self.creation_time = datetime.now(tz=timezone.utc)
         self.deletion_time = None
+        self.change_set_id = None
 
         self.stack_name = request_payload["StackName"]
-        self.change_set_name = request_payload.get("ChangeSetName")
         self.parameters = request_payload.get("Parameters", [])
         self.stack_id = arns.cloudformation_stack_arn(
             self.stack_name,
@@ -159,7 +157,6 @@ def _store_event(
 
     def describe_details(self) -> ApiStack:
         result = {
-            "ChangeSetId": self.change_set_id,
             "CreationTime": self.creation_time,
             "DeletionTime": self.deletion_time,
             "StackId": self.stack_id,
@@ -176,6 +173,9 @@ def describe_details(self) -> ApiStack:
             "RollbackConfiguration": {},
             "Tags": [],
         }
+        if change_set_id := self.change_set_id:
+            result["ChangeSetId"] = change_set_id
+
         if self.resolved_outputs:
             describe_outputs = []
             for key, value in self.resolved_outputs.items():
@@ -191,6 +191,11 @@ def describe_details(self) -> ApiStack:
         return result
 
 
+class ChangeSetRequestPayload(TypedDict, total=False):
+    ChangeSetName: str
+    ChangeSetType: NotRequired[ChangeSetType]
+
+
 class ChangeSet:
     change_set_name: str
     change_set_id: str
@@ -203,8 +208,8 @@ class ChangeSet:
     def __init__(
         self,
         stack: Stack,
-        request_payload: CreateChangeSetInput,
-        template: StackTemplate | None = None,
+        request_payload: ChangeSetRequestPayload,
+        template: dict | None = None,
     ):
         self.stack = stack
         self.template = template