fix(cli): hotswap cannot evaluate nested stacks within nested stacks

Author: Amplifiyer

packages/aws-cdk/lib/api/evaluate-cloudformation-template.ts

@@ -387,7 +387,7 @@ export class EvaluateCloudFormationTemplate {
 
     if (foundResource.ResourceType == 'AWS::CloudFormation::Stack' && attribute?.startsWith('Outputs.')) {
       // need to resolve attributes from another stack's Output section
-      const dependantStackName = this.nestedStackNames[logicalId]?.nestedStackPhysicalName;
+      const dependantStackName = this.findNestedStack(logicalId, this.nestedStackNames);
       if (!dependantStackName) {
         //this is a newly created nested stack and cannot be hotswapped
         return undefined;
@@ -406,6 +406,19 @@ export class EvaluateCloudFormationTemplate {
     return this.formatResourceAttribute(foundResource, attribute);
   }
 
+  private findNestedStack(logicalId: string, nestedStackNames: {
+    [nestedStackLogicalId: string]: NestedStackNames;
+  }): string | undefined {
+    for (const [nestedStackLogicalId, { nestedChildStackNames, nestedStackPhysicalName }] of Object.entries(nestedStackNames)) {
+      if (nestedStackLogicalId === logicalId) {
+        return nestedStackPhysicalName;
+      }
+      const checkInNestedChildStacks = this.findNestedStack(logicalId, nestedChildStackNames);
+      if (checkInNestedChildStacks) return checkInNestedChildStacks;
+    }
+    return undefined;
+  }
+
   private formatResourceAttribute(resource: AWS.CloudFormation.StackResourceSummary, attribute: string | undefined): string | undefined {
     const physicalId = resource.PhysicalResourceId;
 

packages/aws-cdk/test/api/hotswap/nested-stacks-hotswap.test.ts

@@ -826,10 +826,12 @@ describe.each([HotswapMode.FALL_BACK, HotswapMode.HOTSWAP_ONLY])('%p mode', (hot
     });
   });
 
-  test('can hotswap a lambda function in a 1-level nested stack with dependency on a output of sibling stack', async () => {
-    // GIVEN: RootStack has two child stacks `NestedLambdaStack` and `NestedSiblingStack`. `NestedLambdaStack`
-    // takes two parameters s3Key and s3Bucket and use them for a Lambda function.
-    // RootStack resolves s3Bucket from a root template parameter and s3Key through output of `NestedSiblingStack`
+  test('can hotswap a lambda function in a 2-level nested stack with dependency on a output of 2nd level sibling stack', async () => {
+    // GIVEN: RootStack has one child stack `FirstLevelRootStack` which further has two child stacks
+    // `NestedLambdaStack` and `NestedSiblingStack`. `NestedLambdaStack` takes two parameters s3Key
+    // and s3Bucket and use them for a Lambda function.
+    // RootStack resolves s3Bucket from a root template parameter and passed to FirstLevelRootStack which
+    // resolves s3Key through output of `NestedSiblingStack`
     hotswapMockSdkProvider = setup.setupHotswapNestedStackTests('RootStack');
     mockUpdateLambdaCode = jest.fn().mockReturnValue({});
     hotswapMockSdkProvider.stubLambda({
@@ -838,6 +840,34 @@ describe.each([HotswapMode.FALL_BACK, HotswapMode.HOTSWAP_ONLY])('%p mode', (hot
 
     const rootStack = testStack({
       stackName: 'RootStack',
+      template: {
+        Resources: {
+          FirstLevelRootStack: {
+            Type: 'AWS::CloudFormation::Stack',
+            Properties: {
+              TemplateURL: 'https://www.magic-url.com',
+              Parameters: {
+                S3BucketParam: {
+                  Ref: 'S3BucketParam',
+                },
+              },
+            },
+            Metadata: {
+              'aws:asset:path': 'one-stack-with-two-nested-stacks-stack.template.json',
+            },
+          },
+        },
+        Parameters: {
+          S3BucketParam: {
+            Type: 'String',
+            Description: 'S3 bucket for asset',
+          },
+        },
+      },
+    });
+
+    const firstLevelRootStack = testStack({
+      stackName: 'FirstLevelRootStack',
       template: {
         Resources: {
           NestedLambdaStack: {
@@ -869,11 +899,11 @@ describe.each([HotswapMode.FALL_BACK, HotswapMode.HOTSWAP_ONLY])('%p mode', (hot
               'aws:asset:path': 'one-output-stack.nested.template.json',
             },
           },
-          Parameters: {
-            S3BucketParam: {
-              Type: 'String',
-              Description: 'S3 bucket for asset',
-            },
+        },
+        Parameters: {
+          S3BucketParam: {
+            Type: 'String',
+            Description: 'S3 bucket for asset',
           },
         },
       },
@@ -913,10 +943,17 @@ describe.each([HotswapMode.FALL_BACK, HotswapMode.HOTSWAP_ONLY])('%p mode', (hot
     });
 
     setup.addTemplateToCloudFormationLookupMock(rootStack);
+    setup.addTemplateToCloudFormationLookupMock(firstLevelRootStack);
     setup.addTemplateToCloudFormationLookupMock(nestedLambdaStack);
     setup.addTemplateToCloudFormationLookupMock(nestedSiblingStack);
 
     setup.pushNestedStackResourceSummaries('RootStack',
+      setup.stackSummaryOf('FirstLevelRootStack', 'AWS::CloudFormation::Stack',
+        'arn:aws:cloudformation:bermuda-triangle-1337:123456789012:stack/FirstLevelRootStack/abcd',
+      ),
+    );
+
+    setup.pushNestedStackResourceSummaries('FirstLevelRootStack',
       setup.stackSummaryOf('NestedLambdaStack', 'AWS::CloudFormation::Stack',
         'arn:aws:cloudformation:bermuda-triangle-1337:123456789012:stack/NestedLambdaStack/abcd',
       ),

packages/aws-cdk/test/nested-stack-templates/one-stack-with-two-nested-stacks-stack.template.json

@@ -0,0 +1,38 @@
+{
+  "Resources": {
+    "NestedLambdaStack": {
+      "Type": "AWS::CloudFormation::Stack",
+      "Properties": {
+        "TemplateURL": "https://www.magic-url.com",
+        "Parameters": {
+          "referenceToS3BucketParam": {
+            "Ref": "S3BucketParam"
+          },
+          "referenceToS3StackKeyOutput": {
+            "Fn::GetAtt": [
+              "NestedSiblingStack",
+              "Outputs.NestedOutput"
+            ]
+          }
+        }
+      },
+      "Metadata": {
+        "aws:asset:path": "one-lambda-stack-with-dependency-on-sibling-stack-output.nested.template.json"
+      }
+    },
+    "NestedSiblingStack": {
+      "Type": "AWS::CloudFormation::Stack",
+      "Properties": {
+        "TemplateURL": "https://www.magic-url.com"
+      },
+      "Metadata": {
+        "aws:asset:path": "one-output-stack.nested.template.json"
+      }
+    }
+  },
+  "Parameters": {
+    "S3BucketParam": {
+      "Type": "String"
+    }
+  }
+}