associate custom Elastic IP to NAT Gateway with AWS CDK

Question

After struggling with that for several hours, here is my question. I am using CDK to create a VPC in the most simple form currently:

let vpc = new Vpc(this, "myVpc", {maxAzs: 1});

This gets me a public Subnet and a private one with the all the Gateways (internet and NAT). My NAT Gateway got a public EIP from the AWS pool. Of course when i destroy the stack and re-create it, i will get a new EIP from AWS, but THIS i dont want.

What i want is: Creating an Elastic IP outside of my CDK project (manually via CLI or AWS Console) and attach it to my NAT GW, so that even after destroying the stack, i can re-attach my (external) EIP to the "new" NAT GW.

So there must be a way to not have the AWS::EC2::NatGateway created automatically by the VPC but manually with the proper EIP association and then attach it to the VPC / Public Subnet. Pretty much the same way i can explicitly define Subnets and associate them with the VPC instead of CDK construct magic.

Answer 1

You can refer here https://github.com/aws/aws-cdk/issues/4067 at the last post.

You can define EIP allocations then assign it into Nat Gateway while CDK deployment.

Of course, you must manually create EIP first.

Answer 2

For Java CDK you can use natGatewayProvider(NatProvider.gateway(NatGatewayProps.builder().eipAllocationIds(Collections.singletonList("eipalloc-id")).build()))

The full example to create VPC with manually configured EIP for NAT:

Vpc.Builder.create(this, "vpc")
        .natGateways(1)
        .natGatewayProvider(NatProvider.gateway(NatGatewayProps.builder().eipAllocationIds(Collections.singletonList("eipalloc-id")).build()))
        .maxAzs(3)
        .subnetConfiguration(
            Arrays.asList(
                SubnetConfiguration.builder()
                    .subnetType(SubnetType.PRIVATE)
                    .cidrMask(24)
                    .name("mc")
                    .build(),
                SubnetConfiguration.builder()
                    .subnetType(SubnetType.PUBLIC)
                    .cidrMask(24)
                    .name("Ingress")
                    .build(),
                SubnetConfiguration.builder()
                    .subnetType(SubnetType.ISOLATED)
                    .cidrMask(24)
                    .name("app")
                    .build()
            )
        )
        .cidr("10.0.0.0/16").build();

For other languages look into https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-ec2.Vpc.html#natgatewayprovider