AutoScalingGroup vpc_subnets doesn't seem to do anything

[jordan-dimov]

🐛 Bug Report

What is the problem?

I'm using cdk with Python and have an AutoScalingGroup launching an EC2 instance within a vpc. Everything was working fine, except when I tried to add vpc_subnets to the constructor in order to specify which subnet I want the instance to launch in, cdk synth resulted in no differences to the CloudFormation templates and cdk diff doesn't reflect that either.

Reproduction Steps

If you have code like the following, the vpc_subnets parameter doesn't seem to be honoured:

aws_autoscaling.AutoScalingGroup(
    self, "MyAutoscalingGroup", 
    vpc=my_vpc,
    instance_type=aws_ec2.InstanceType.of(aws_ec2.InstanceClass.STANDARD5, aws_ec2.InstanceSize.XLARGE),
    machine_image=aws_ec2.WindowsImage(
        version=aws_ec2.WindowsVersion.WINDOWS_SERVER_2019
    ),
    vpc_subnets=aws_ec2.SubnetSelection(subnet_name="subnet-0af00000000000000"),  # (using valid subnet ID here)
)

Environment

• CDK CLI Version: 1.6.0
• Module Version: aws-cdk.aws-autoscaling==1.6.0
• OS: Ubuntu
• Language: Python

[rix0rrr]

This seems to be a duplicate of #3548 (select individual subnets).

It's also a misuse of the API, which will be made more clear in an upcoming PR.