fix(aws-rds): fromDatabaseInstanceAttributes incorrectly stringifies …

…ports with tokens (#16286)

Closes #11813. Fixes `port` with tokens being incorrectly stringified in `fromDatabaseInstanceAttributes()`.

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-rds/lib/instance.ts

@@ -5,7 +5,7 @@ import * as kms from '@aws-cdk/aws-kms';
 import * as logs from '@aws-cdk/aws-logs';
 import * as s3 from '@aws-cdk/aws-s3';
 import * as secretsmanager from '@aws-cdk/aws-secretsmanager';
-import { ArnComponents, Duration, FeatureFlags, IResource, Lazy, RemovalPolicy, Resource, Stack, Token } from '@aws-cdk/core';
+import { ArnComponents, Duration, FeatureFlags, IResource, Lazy, RemovalPolicy, Resource, Stack, Token, Tokenization } from '@aws-cdk/core';
 import * as cxapi from '@aws-cdk/cx-api';
 import { Construct } from 'constructs';
 import { DatabaseSecret } from './database-secret';
@@ -124,7 +124,7 @@ export abstract class DatabaseInstanceBase extends Resource implements IDatabase
       });
       public readonly instanceIdentifier = attrs.instanceIdentifier;
       public readonly dbInstanceEndpointAddress = attrs.instanceEndpointAddress;
-      public readonly dbInstanceEndpointPort = attrs.port.toString();
+      public readonly dbInstanceEndpointPort = Tokenization.stringifyNumber(attrs.port);
       public readonly instanceEndpoint = new Endpoint(attrs.instanceEndpointAddress, attrs.port);
       public readonly engine = attrs.engine;
       protected enableIamAuthentication = true;

packages/@aws-cdk/aws-rds/test/instance.test.ts

@@ -401,6 +401,35 @@ describe('instance', () => {
 
 
     });
+
+    test('can create a new database instance with fromDatabaseInstanceAttributes using a token for the port', () => {
+      // GIVEN
+      const databasePort = new cdk.CfnParameter(stack, 'DatabasePort', {
+        type: 'Number',
+        default: 5432,
+      }).valueAsNumber;
+
+      // WHEN
+      const instance = rds.DatabaseInstance.fromDatabaseInstanceAttributes(stack, 'DatabaseInstance', {
+        instanceIdentifier: '',
+        securityGroups: [],
+        instanceEndpointAddress: '',
+        port: databasePort,
+      });
+
+      new cdk.CfnOutput(stack, 'portOutput', {
+        exportName: 'databaseUrl',
+        value: `${instance.dbInstanceEndpointPort}`,
+      });
+
+      // THEN
+      expect(stack).toHaveOutput({
+        exportName: 'databaseUrl',
+        outputValue: {
+          Ref: 'DatabasePort',
+        },
+      });
+    });
   });
 
   test('create a read replica in the same region - with the subnet group name', () => {