aws-ec2: InterfaceVpcEndpoint does not allow private DNS disabling

[strax]

Describe the bug

The construct @aws-cdk/aws-ec2.InterfaceVpcEndpoint cannot be used to connect to endpoint services that do not support private DNS due to a logic bug.

The issue is at https://github.com/awslabs/aws-cdk/blob/master/packages/%40aws-cdk/aws-ec2/lib/vpc-endpoint.ts#L398 – if the user passes privateDnsEnabled: false to the construct props, the expression at the aforementioned line expands to false || true which always evaluates to true.

To Reproduce

Synthesize this:

 new InterfaceVpcEndpoint(this, "MyTestEndpoint", {
      service,
      vpc,
      privateDnsEnabled: false
})

The resulting template has property PrivateDnsEnabled: true in the endpoint resource definition.

Expected behavior

PrivateDnsEnabled is set to false iff it is missing (undefined) in props.

Version:

• OS: MacOS 10.14.4
• Programming Language: TypeScript
• CDK Version: 0.31.0