Control over VPC AZs

❓ General Issue

Attempting to create a VPC in ap-northeast-1 with 2 AZs and one NatGateway. Upon deploy the stack fails with the error “Nat Gateway is not available in this availability zone”

apne1-az3 in this region does not have NATGateway support, unfortunately it is mapped to AZ ap-northeast-1a in my account.

example:

vpc = aws_ec2.Vpc(
            self,
            id='prod_vpc',
            cidr='10.199.0.0/16',
            enable_dns_hostnames=False,
            enable_dns_support=True,
            nat_gateways=1,
            max_azs=2,
            subnet_configuration=[
                aws_ec2.SubnetConfiguration(
                    cidr_mask=24,
                    name='public',
                    subnet_type=aws_ec2.SubnetType.PUBLIC
                ),
                aws_ec2.SubnetConfiguration(
                    cidr_mask=20,
                    name='application',
                    subnet_type=aws_ec2.SubnetType.PRIVATE
                )
            ]
        )

Running this in a different account in the same region can also have the same issue.

expected behavior:

If a NATGateway is requested then the CDK should check for support in the AZ before selection. It appears that the CDK is processing in logical order?

question:

Is there a workaround for this?

Environment

• CDK CLI Version: 1.21
• OS: OSX Catalina
• Language: Python

[hljadmin]

As an infrastructure designer having the ability to determine a list of AZs to use in a VPC would be invaluable. This is especially important in situations where deployments across accounts as well as regions come into play.

[hljadmin]

Thank you. Unfortunately my skills in node are not up to doing this task. Hopefully someone can pick up this request. I think it would be clearer if the AZ was a param in the create of the VPC.

Had to do some digging but finally figured out one way to do this in python:

#only use these availability zones
self.node.set_context(
    key=f'availability-zones:account={self.account}:region={self.region}',
    value=['zone-1b', 'zone-1c']
)