localstack · MEPalma · May 21, 2025 · May 19, 2025
@@ -256,21 +256,24 @@ class NodeResource(ChangeSetNode):
     type_: Final[ChangeSetTerminal]
     condition_reference: Final[Optional[TerminalValue]]
     properties: Final[NodeProperties]
+    depends_on: Final[Optional[NodeDependsOn]]
 
     def __init__(
         self,
         scope: Scope,
         change_type: ChangeType,
         name: str,
         type_: ChangeSetTerminal,
-        condition_reference: TerminalValue,
         properties: NodeProperties,
+        condition_reference: Optional[TerminalValue],
+        depends_on: Optional[NodeDependsOn],
     ):
         super().__init__(scope=scope, change_type=change_type)
         self.name = name
         self.type_ = type_
-        self.condition_reference = condition_reference
         self.properties = properties
+        self.condition_reference = condition_reference
+        self.depends_on = depends_on
 
 
 class NodeProperties(ChangeSetNode):
@@ -281,6 +284,14 @@ def __init__(self, scope: Scope, change_type: ChangeType, properties: list[NodeP
         self.properties = properties
 
 
+class NodeDependsOn(ChangeSetNode):
+    depends_on: Final[NodeArray]
+
+    def __init__(self, scope: Scope, change_type: ChangeType, depends_on: NodeArray):
+        super().__init__(scope=scope, change_type=change_type)
+        self.depends_on = depends_on
+
+
 class NodeProperty(ChangeSetNode):
     name: Final[str]
     value: Final[ChangeSetEntity]
@@ -365,6 +376,7 @@ def __init__(self, scope: Scope, value: Any):
 ValueKey: Final[str] = "Value"
 ExportKey: Final[str] = "Export"
 OutputsKey: Final[str] = "Outputs"
+DependsOnKey: Final[str] = "DependsOn"
 # TODO: expand intrinsic functions set.
 RefKey: Final[str] = "Ref"
 FnIfKey: Final[str] = "Fn::If"
@@ -770,12 +782,20 @@ def _visit_resource(
         scope_condition, (before_condition, after_condition) = self._safe_access_in(
             scope, ConditionKey, before_resource, after_resource
         )
-        # TODO: condition references should be resolved for the condition's change_type?
         if before_condition or after_condition:
             condition_reference = self._visit_terminal_value(
                 scope_condition, before_condition, after_condition
             )
 
+        depends_on = None
+        scope_depends_on, (before_depends_on, after_depends_on) = self._safe_access_in(
+            scope, DependsOnKey, before_resource, after_resource
+        )
+        if before_depends_on or after_depends_on:
+            depends_on = self._visit_depends_on(
+                scope_depends_on, before_depends_on, after_depends_on
+            )
+
         scope_properties, (before_properties, after_properties) = self._safe_access_in(
             scope, PropertiesKey, before_resource, after_resource
         )
@@ -793,8 +813,9 @@ def _visit_resource(
             change_type=change_type,
             name=resource_name,
             type_=terminal_value_type,
-            condition_reference=condition_reference,
             properties=properties,
+            condition_reference=condition_reference,
+            depends_on=depends_on,
         )
         self._visited_scopes[scope] = node_resource
         return node_resource
@@ -925,6 +946,38 @@ def _visit_parameters(
         self._visited_scopes[scope] = node_parameters
         return node_parameters
 
+    @staticmethod
+    def _normalise_depends_on_value(value: Maybe[str | list[str]]) -> Maybe[list[str]]:
+        # To simplify downstream logics, reduce the type options to array of strings.
+        # TODO: Add integrations tests for DependsOn validations (invalid types, duplicate identifiers, etc.)
+        if isinstance(value, NothingType):
+            return value
+        if isinstance(value, str):
+            value = [value]
+        elif isinstance(value, list):
+            value.sort()
+        else:
+            raise RuntimeError(
+                f"Invalid type for DependsOn, expected a String or Array of String, but got: '{value}'"
+            )
+        return value
+
+    def _visit_depends_on(
+        self,
+        scope: Scope,
+        before_depends_on: Maybe[str | list[str]],
+        after_depends_on: Maybe[str | list[str]],
+    ) -> NodeDependsOn:
+        before_depends_on = self._normalise_depends_on_value(value=before_depends_on)
+        after_depends_on = self._normalise_depends_on_value(value=after_depends_on)
+        node_array = self._visit_array(
+            scope=scope, before_array=before_depends_on, after_array=after_depends_on
+        )
+        node_depends_on = NodeDependsOn(
+            scope=scope, change_type=node_array.change_type, depends_on=node_array
+        )
+        return node_depends_on
+
     def _visit_condition(
         self,
         scope: Scope,

@@ -7,6 +7,7 @@
 from localstack.aws.api.cloudformation import ChangeAction, StackStatus
 from localstack.constants import INTERNAL_AWS_SECRET_ACCESS_KEY
 from localstack.services.cloudformation.engine.v2.change_set_model import (
+    NodeDependsOn,
     NodeOutput,
     NodeParameter,
     NodeResource,
@@ -77,6 +78,23 @@ def _after_resource_physical_id(self, resource_logical_id: str) -> str:
             logical_resource_id=resource_logical_id, resolved_resources=after_resolved_resources
         )
 
+    def visit_node_depends_on(self, node_depends_on: NodeDependsOn) -> PreprocEntityDelta:
+        array_identifiers_delta = super().visit_node_depends_on(node_depends_on=node_depends_on)
+
+        # Visit depends_on resources before returning.
+        depends_on_resource_logical_ids: set[str] = set()
+        if array_identifiers_delta.before:
+            depends_on_resource_logical_ids.update(array_identifiers_delta.before)
+        if array_identifiers_delta.after:
+            depends_on_resource_logical_ids.update(array_identifiers_delta.after)
+        for depends_on_resource_logical_id in depends_on_resource_logical_ids:
+            node_resource = self._get_node_resource_for(
+                resource_name=depends_on_resource_logical_id, node_template=self._node_template
+            )
+            self.visit_node_resource(node_resource)
+
+        return array_identifiers_delta
+
     def visit_node_resource(
         self, node_resource: NodeResource
     ) -> PreprocEntityDelta[PreprocResource, PreprocResource]:

@@ -7,6 +7,7 @@
     ChangeType,
     NodeArray,
     NodeCondition,
+    NodeDependsOn,
     NodeDivergence,
     NodeIntrinsicFunction,
     NodeMapping,
@@ -81,6 +82,7 @@ class PreprocResource:
     condition: Optional[bool]
     resource_type: str
     properties: PreprocProperties
+    depends_on: Optional[list[str]]
 
     def __init__(
         self,
@@ -89,12 +91,14 @@ def __init__(
         condition: Optional[bool],
         resource_type: str,
         properties: PreprocProperties,
+        depends_on: Optional[list[str]],
     ):
         self.logical_id = logical_id
         self.physical_resource_id = physical_resource_id
         self.condition = condition
         self.resource_type = resource_type
         self.properties = properties
+        self.depends_on = depends_on
 
     @staticmethod
     def _compare_conditions(c1: bool, c2: bool):
@@ -533,6 +537,10 @@ def visit_node_parameter(self, node_parameter: NodeParameter) -> PreprocEntityDe
 
         return PreprocEntityDelta(before=before, after=after)
 
+    def visit_node_depends_on(self, node_depends_on: NodeDependsOn) -> PreprocEntityDelta:
+        array_identifiers_delta = self.visit(node_depends_on.depends_on)
+        return array_identifiers_delta
+
     def visit_node_condition(self, node_condition: NodeCondition) -> PreprocEntityDelta:
         delta = self.visit(node_condition.body)
         return delta
@@ -638,6 +646,13 @@ def visit_node_resource(
             condition_before = condition_delta.before
             condition_after = condition_delta.after
 
+        depends_on_before = None
+        depends_on_after = None
+        if node_resource.depends_on is not None:
+            depends_on_delta = self.visit_node_depends_on(node_resource.depends_on)
+            depends_on_before = depends_on_delta.before
+            depends_on_after = depends_on_delta.after
+
         type_delta = self.visit(node_resource.type_)
         properties_delta: PreprocEntityDelta[PreprocProperties, PreprocProperties] = self.visit(
             node_resource.properties
@@ -656,6 +671,7 @@ def visit_node_resource(
                 condition=condition_before,
                 resource_type=type_delta.before,
                 properties=properties_delta.before,
+                depends_on=depends_on_before,
             )
         if change_type != ChangeType.REMOVED and condition_after is None or condition_after:
             logical_resource_id = node_resource.name
@@ -671,6 +687,7 @@ def visit_node_resource(
                 condition=condition_after,
                 resource_type=type_delta.after,
                 properties=properties_delta.after,
+                depends_on=depends_on_after,
             )
         return PreprocEntityDelta(before=before, after=after)
 

@@ -5,6 +5,7 @@
     NodeArray,
     NodeCondition,
     NodeConditions,
+    NodeDependsOn,
     NodeDivergence,
     NodeIntrinsicFunction,
     NodeMapping,
@@ -73,6 +74,9 @@ def visit_node_conditions(self, node_conditions: NodeConditions):
     def visit_node_condition(self, node_condition: NodeCondition):
         self.visit_children(node_condition)
 
+    def visit_node_depends_on(self, node_depends_on: NodeDependsOn):
+        self.visit_children(node_depends_on)
+
     def visit_node_resources(self, node_resources: NodeResources):
         self.visit_children(node_resources)
 

@@ -59,7 +59,6 @@
 """
 
 
-@pytest.mark.skip(reason="no support for DependsOn")
 # this is an `only_localstack` test because it makes use of _custom_id_ tag
 @markers.aws.only_localstack
 def test_cfn_apigateway_aws_integration(deploy_cfn_template, aws_client):
@@ -143,7 +142,10 @@ def test_cfn_apigateway_swagger_import(deploy_cfn_template, echo_http_server_pos
     assert content["url"].endswith("/post")
 
 
-@pytest.mark.skip(reason="No support for DependsOn")
+@pytest.mark.skip(
+    reason="The v2 provider appears to instead return the correct url: "
+    "https://e1i3grfiws.execute-api.us-east-1.localhost.localstack.cloud/prod/"
+)
 @markers.aws.only_localstack
 def test_url_output(httpserver, deploy_cfn_template):
     httpserver.expect_request("").respond_with_data(b"", 200)
@@ -225,7 +227,7 @@ def test_cfn_with_apigateway_resources(deploy_cfn_template, aws_client, snapshot
     # assert not apis
 
 
-@pytest.mark.skip(reason="DependsOn is unsupported")
+@pytest.mark.skip(reason="NotFoundException Invalid Method identifier specified")
 @markers.aws.validated
 @markers.snapshot.skip_snapshot_verify(
     paths=[
@@ -279,7 +281,6 @@ def test_cfn_deploy_apigateway_models(deploy_cfn_template, snapshot, aws_client)
     assert result.status_code == 400
 
 
-@pytest.mark.skip(reason="DependsOn is unsupported")
 @markers.aws.validated
 def test_cfn_deploy_apigateway_integration(deploy_cfn_template, snapshot, aws_client):
     snapshot.add_transformer(snapshot.transform.key_value("cacheNamespace"))

@@ -15,7 +15,6 @@
         "per-resource-events..*",
         "delete-describe..*",
         #
-        "$..ChangeSetId",  # An issue for the WIP executor
         # Before/After Context
         "$..Capabilities",
         "$..NotificationARNs",