localstack · MEPalma · Jun 3, 2025 · May 19, 2025 · May 20, 2025 · May 21, 2025
@@ -425,6 +425,7 @@ def __init__(self, scope: Scope, value: Any):
 FnTransform: Final[str] = "Fn::Transform"
 FnSelect: Final[str] = "Fn::Select"
 FnSplit: Final[str] = "Fn::Split"
+FnGetAZs: Final[str] = "Fn::GetAZs"
 INTRINSIC_FUNCTIONS: Final[set[str]] = {
     RefKey,
     FnIfKey,
@@ -437,6 +438,7 @@ def __init__(self, scope: Scope, value: Any):
     FnTransform,
     FnSelect,
     FnSplit,
+    FnGetAZs,
 }
 
 

@@ -3,6 +3,10 @@
 import re
 from typing import Any, Final, Generic, Optional, TypeVar
 
+from botocore.exceptions import ClientError
+
+from localstack.aws.api.ec2 import AvailabilityZoneList, DescribeAvailabilityZonesResult
+from localstack.aws.connect import connect_to
 from localstack.services.cloudformation.engine.transformers import (
     Transformer,
     execute_macro,
@@ -677,7 +681,7 @@ def _compute_fn_select(args: list[Any]) -> Any:
 
     def visit_node_intrinsic_function_fn_split(
         self, node_intrinsic_function: NodeIntrinsicFunction
-    ) -> PreprocEntityDelta:
+    ):
         # TODO: add further support for schema validation
         arguments_delta = self.visit(node_intrinsic_function.arguments)
         arguments_before = arguments_delta.before
@@ -703,6 +707,47 @@ def _compute_fn_split(args: list[Any]) -> Any:
 
         return PreprocEntityDelta(before=before, after=after)
 
+    def visit_node_intrinsic_function_fn_get_a_zs(
+        self, node_intrinsic_function: NodeIntrinsicFunction
+    ) -> PreprocEntityDelta:
+        # TODO: add further support for schema validation
+        arguments_delta = self.visit(node_intrinsic_function.arguments)
+        arguments_before = arguments_delta.before
+        arguments_after = arguments_delta.after
+
+        def _compute_fn_get_a_zs(region) -> Any:
+            if not isinstance(region, str):
+                raise RuntimeError(f"Invalid region value for Fn::GetAZs: '{region}'")
+
+            if not region:
+                region = self._change_set.region_name
+
+            account_id = self._change_set.account_id
+            ec2_client = connect_to(aws_access_key_id=account_id, region_name=region).ec2
+            try:
+                describe_availability_zones_result: DescribeAvailabilityZonesResult = (
+                    ec2_client.describe_availability_zones()
+                )
+            except ClientError:
+                raise RuntimeError(
+                    "Could not describe zones availability whilst evaluating Fn::GetAZs"
+                )
+            availability_zones: AvailabilityZoneList = describe_availability_zones_result[
+                "AvailabilityZones"
+            ]
+            azs = [az["ZoneName"] for az in availability_zones]
+            return azs
+
+        before = Nothing
+        if not is_nothing(arguments_before):
+            before = _compute_fn_get_a_zs(arguments_before)
+
+        after = Nothing
+        if not is_nothing(arguments_after):
+            after = _compute_fn_get_a_zs(arguments_after)
+
+        return PreprocEntityDelta(before=before, after=after)
+
     def visit_node_intrinsic_function_fn_find_in_map(
         self, node_intrinsic_function: NodeIntrinsicFunction
     ) -> PreprocEntityDelta:

@@ -128,6 +128,11 @@ def visit_node_intrinsic_function_fn_split(
     ):
         self.visit_children(node_intrinsic_function)
 
+    def visit_node_intrinsic_function_fn_get_a_zs(
+        self, node_intrinsic_function: NodeIntrinsicFunction
+    ):
+        self.visit_children(node_intrinsic_function)
+
     def visit_node_intrinsic_function_fn_sub(self, node_intrinsic_function: NodeIntrinsicFunction):
         self.visit_children(node_intrinsic_function)
 

@@ -70,7 +70,7 @@ def test_simple_route_table_creation(deploy_cfn_template, aws_client, snapshot):
     #     ec2.describe_route_tables(RouteTableIds=[route_table_id])
 
 
-@pytest.mark.skip(reason="CFNV2:Fn::Select, CFNV2:Fn::GatAZs")
+@pytest.mark.skip(reason="CFNV2:Other")
 @markers.aws.validated
 def test_vpc_creates_default_sg(deploy_cfn_template, aws_client):
     result = deploy_cfn_template(
@@ -109,7 +109,6 @@ def test_cfn_with_multiple_route_tables(deploy_cfn_template, aws_client):
     assert len(resp["RouteTables"]) == 4
 
 
-@pytest.mark.skip(reason="CFNV2:Fn::Select, CFNV2:Fn::GatAZs")
 @markers.aws.validated
 @markers.snapshot.skip_snapshot_verify(
     paths=["$..PropagatingVgws", "$..Tags", "$..Tags..Key", "$..Tags..Value"]
@@ -165,7 +164,6 @@ def test_dhcp_options(aws_client, deploy_cfn_template, snapshot):
     snapshot.match("description", response["DhcpOptions"][0])
 
 
-@pytest.mark.skip(reason="CFNV2:Fn::Select, CFNV2:Fn::GatAZs")
 @markers.aws.validated
 @markers.snapshot.skip_snapshot_verify(
     paths=[

@@ -197,7 +197,6 @@ def test_cidr_function(self, deploy_cfn_template):
 
         assert deployed.outputs["Address"] == "10.0.0.0/24"
 
-    @pytest.mark.skip(reason="CFNV2:Fn::GetAZs")
     @pytest.mark.parametrize(
         "region",
         [