feat: Return early during linking if no destination resources are fou…

…nd (aws#5220) * Returns during linking if no destination resources are found * Updated comment to correctly reflect state * Cleaned extra word --------- Co-authored-by: Mohamed Elasmar <[email protected]>
Leo10Gama · Jun 22, 2023 · 5446146 · 5446146
1 parent e74caef
commit 5446146
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diff --git a/samcli/hook_packages/terraform/hooks/prepare/resource_linking.py b/samcli/hook_packages/terraform/hooks/prepare/resource_linking.py
@@ -234,9 +234,12 @@ def _link_using_terraform_config(self, source_tf_resource: TFResource, cfn_resou
             )
         if not dest_resources:
             LOG.debug(
-                "There are destination resources defined for for the source resource %s",
+                "There are no destination resources defined for the source resource %s, skipping linking.",
                 source_tf_resource.full_address,
             )
+
+            return
+
         for cfn_resource in cfn_resources:
             self._resource_pair.cfn_resource_update_call_back_function(cfn_resource, dest_resources)  # type: ignore
 
@@ -287,7 +290,12 @@ def _link_using_linking_fields(self, cfn_resource: Dict) -> None:
             else ExistingResourceReference(value)
             for value in values
         ]
-        LOG.debug("The value of the source resource linking field after mapping $s", dest_resources)
+
+        if not dest_resources:
+            LOG.debug("Skipping linking call back, no destination resources discovered.")
+            return
+
+        LOG.debug("The value of the source resource linking field after mapping %s", dest_resources)
         self._resource_pair.cfn_resource_update_call_back_function(cfn_resource, dest_resources)  # type: ignore
 
     def _process_resolved_resources(

diff --git a/tests/unit/hook_packages/terraform/hooks/prepare/test_resource_linking.py b/tests/unit/hook_packages/terraform/hooks/prepare/test_resource_linking.py
@@ -1129,6 +1129,21 @@ def setUp(self) -> None:
             linking_exceptions=self.linker_exceptions,
         )
 
+    def test_applied_empty_destination_skip_call_back(self):
+        resource_linker = ResourceLinker(self.sample_resource_linking_pair)
+        resource_linker._link_using_linking_fields({"Properties": {"Layers": []}})
+
+        self.sample_resource_linking_pair.cfn_resource_update_call_back_function.assert_not_called()
+
+    @patch("samcli.hook_packages.terraform.hooks.prepare.resource_linking._resolve_resource_attribute")
+    @patch("samcli.hook_packages.terraform.hooks.prepare.resource_linking.ResourceLinker._process_resolved_resources")
+    def test_config_empty_destination_skip_call_back(self, proccess_resolved_res_mock, resolve_resource_attr_mock):
+        resource_linker = ResourceLinker(self.sample_resource_linking_pair)
+        proccess_resolved_res_mock.return_value = []
+        resource_linker._link_using_terraform_config(Mock(), Mock())
+
+        self.sample_resource_linking_pair.cfn_resource_update_call_back_function.assert_not_called()
+
     def test_handle_linking_mix_of_applied_and_non_applied_resources(self):
         cfn_resource_depend_on_applied_resources = {
             "Type": "AWS::Lambda::Function",