fix(route53): cannot delete existing alias record (#20858)

For an alias record, the `ListResourceRecordSets` call returns an empty array
that the `ChangeResourceRecordSets` call doesn't accept.

Remove undefined and empty arrays when calling `ChangeResourceRecordSets`.

See aws/aws-sdk-js#3411

Closes #20847


----

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Author: jogold

packages/@aws-cdk/aws-route53/lib/delete-existing-record-set-handler/index.ts

@@ -35,15 +35,13 @@ export async function handler(event: AWSLambda.CloudFormationCustomResourceEvent
     ChangeBatch: {
       Changes: [{
         Action: 'DELETE',
-        ResourceRecordSet: {
+        ResourceRecordSet: removeUndefinedAndEmpty({
           Name: existingRecord.Name,
           Type: existingRecord.Type,
-          // changeResourceRecordSets does not correctly handle undefined values
-          // https://github.com/aws/aws-sdk-js/issues/3506
-          ...existingRecord.TTL ? { TTL: existingRecord.TTL } : {},
-          ...existingRecord.AliasTarget ? { AliasTarget: existingRecord.AliasTarget } : {},
-          ...existingRecord.ResourceRecords ? { ResourceRecords: existingRecord.ResourceRecords } : {},
-        },
+          TTL: existingRecord.TTL,
+          AliasTarget: existingRecord.AliasTarget,
+          ResourceRecords: existingRecord.ResourceRecords,
+        }),
       }],
     },
   }).promise();
@@ -54,3 +52,17 @@ export async function handler(event: AWSLambda.CloudFormationCustomResourceEvent
     PhysicalResourceId: `${existingRecord.Name}-${existingRecord.Type}`,
   };
 }
+
+// https://github.com/aws/aws-sdk-js/issues/3411
+// https://github.com/aws/aws-sdk-js/issues/3506
+function removeUndefinedAndEmpty<T>(obj: T): T {
+  const ret: { [key: string]: any } = {};
+
+  for (const [k, v] of Object.entries(obj)) {
+    if (v && (!Array.isArray(v) || v.length !== 0)) {
+      ret[k] = v;
+    }
+  }
+
+  return ret as T;
+}

packages/@aws-cdk/aws-route53/test/delete-existing-record-set-handler.test.ts

@@ -133,3 +133,49 @@ test('delete request', async () => {
 
   expect(mockRoute53.changeResourceRecordSets).not.toHaveBeenCalled();
 });
+
+test('with alias target', async () => {
+  mockListResourceRecordSetsResponse.mockResolvedValueOnce({
+    ResourceRecordSets: [
+      {
+        Name: 'dev.cdk.aws.',
+        Type: 'A',
+        TTL: undefined,
+        ResourceRecords: [],
+        AliasTarget: {
+          HostedZoneId: 'hosted-zone-id',
+          DNSName: 'dns-name',
+          EvaluateTargetHealth: false,
+        },
+      },
+    ],
+  });
+
+  mockChangeResourceRecordSetsResponse.mockResolvedValueOnce({
+    ChangeInfo: {
+      Id: 'change-id',
+    },
+  });
+
+  await handler(event);
+
+  expect(mockRoute53.changeResourceRecordSets).toHaveBeenCalledWith({
+    HostedZoneId: 'hosted-zone-id',
+    ChangeBatch: {
+      Changes: [
+        {
+          Action: 'DELETE',
+          ResourceRecordSet: {
+            Name: 'dev.cdk.aws.',
+            Type: 'A',
+            AliasTarget: {
+              HostedZoneId: 'hosted-zone-id',
+              DNSName: 'dns-name',
+              EvaluateTargetHealth: false,
+            },
+          },
+        },
+      ],
+    },
+  });
+});