fix(rds): setting timezone on DatabaseInstance causes internal failure (#6534)

* fix(rds): setting timezone on DatabaseInstance causes internal failure

Per documentation[1], 'Timezone' property is only supported on Microsoft
SQL Server. Setting this property on a DatabaseInstance with a different
database engine causes deployment to fail (1) with a validation error
for a new instance of `AWS::RDS::DBInstance` and (2) internal failure
when modifying an existing instance of `AWS::RDS::DBInstance`.

[1]:https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-rds-database-instance.html#cfn-rds-dbinstance-timezone

fixes #6439

* PR feedback

Author: nija-at

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

@@ -616,7 +616,7 @@ export interface DatabaseInstanceSourceProps extends DatabaseInstanceNewProps {
   readonly allowMajorVersionUpgrade?: boolean;
 
   /**
-   * The time zone of the instance.
+   * The time zone of the instance. This is currently supported only by Microsoft Sql Server.
    *
    * @default - RDS default timezone
    */
@@ -678,6 +678,12 @@ abstract class DatabaseInstanceSource extends DatabaseInstanceNew implements IDa
     this.singleUserRotationApplication = props.engine.singleUserRotationApplication;
     this.multiUserRotationApplication = props.engine.multiUserRotationApplication;
 
+    const timezoneSupport = [ DatabaseInstanceEngine.SQL_SERVER_EE, DatabaseInstanceEngine.SQL_SERVER_EX,
+      DatabaseInstanceEngine.SQL_SERVER_SE, DatabaseInstanceEngine.SQL_SERVER_WEB ];
+    if (props.timezone && !timezoneSupport.includes(props.engine)) {
+      throw new Error(`timezone property can be configured only for Microsoft SQL Server, not ${props.engine.name}`);
+    }
+
     this.sourceCfnProps = {
       ...this.newCfnProps,
       allocatedStorage: props.allocatedStorage ? props.allocatedStorage.toString() : '100',

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

@@ -685,4 +685,37 @@ export = {
 
     test.done();
   },
+
+  'throws when timezone is set for non-sqlserver database engine'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const vpc = new ec2.Vpc(stack, 'vpc');
+    const tzSupportedEngines = [ rds.DatabaseInstanceEngine.SQL_SERVER_EE, rds.DatabaseInstanceEngine.SQL_SERVER_EX,
+      rds.DatabaseInstanceEngine.SQL_SERVER_SE, rds.DatabaseInstanceEngine.SQL_SERVER_WEB ];
+    const tzUnsupportedEngines = [ rds.DatabaseInstanceEngine.MYSQL, rds.DatabaseInstanceEngine.POSTGRES,
+      rds.DatabaseInstanceEngine.ORACLE_EE, rds.DatabaseInstanceEngine.MARIADB ];
+
+    // THEN
+    tzSupportedEngines.forEach((engine) => {
+      test.ok(new rds.DatabaseInstance(stack, `${engine.name}-db`, {
+        engine,
+        instanceClass: ec2.InstanceType.of(ec2.InstanceClass.C5, ec2.InstanceSize.SMALL),
+        masterUsername: 'master',
+        timezone: 'Europe/Zurich',
+        vpc,
+      }));
+    });
+
+    tzUnsupportedEngines.forEach((engine) => {
+      test.throws(() => new rds.DatabaseInstance(stack, `${engine.name}-db`, {
+        engine,
+        instanceClass: ec2.InstanceType.of(ec2.InstanceClass.C5, ec2.InstanceSize.SMALL),
+        masterUsername: 'master',
+        timezone: 'Europe/Zurich',
+        vpc,
+      }), /timezone property can be configured only for Microsoft SQL Server/);
+    });
+
+    test.done();
+  }
 };