aws-ec2: Internet Gateway created when public subnets are reserved

[dontirun]

Describe the bug

An internet gateway is created for a VPC where address space is reserved for public subnets, but the public subnets do not actually exist

Expected Behavior

An internet Gateway is not created for the Vpc when the address space for public subnets are reserved, but no public subnets actually exist

Current Behavior

An internet gateway is created for a VPC where address space is reserved for public subnets, but the public subnets do not actually exist

Reproduction Steps

import * as cdk from 'aws-cdk-lib';
import { SubnetType, Vpc } from 'aws-cdk-lib/aws-ec2';
export class MyStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
    super(scope, id, props);
    new Vpc(this, 'vpc', {
      subnetConfiguration: [
        {
          name: 'Isolated',
          subnetType: SubnetType.PRIVATE_ISOLATED,
          cidrMask: 22,
        },
        {
          name: 'Public',
          subnetType: SubnetType.PUBLIC,
          cidrMask: 26,
          reserved: true,
        },
      ],
    });
  }
};
const app = new cdk.App();
new MyStack(app, 'test');
app.synth();

CloudFormation Output

Resources:
  vpcA2121C38:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: 10.0.0.0/16
      EnableDnsHostnames: true
      EnableDnsSupport: true
      InstanceTenancy: default
      Tags:
        - Key: Name
          Value: test/vpc
    Metadata:
      aws:cdk:path: test/vpc/Resource
  vpcIsolatedSubnet1Subnet8B28CEB3:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone:
        Fn::Select:
          - 0
          - Fn::GetAZs: ""
      CidrBlock: 10.0.0.0/22
      MapPublicIpOnLaunch: false
      Tags:
        - Key: aws-cdk:subnet-name
          Value: Isolated
        - Key: aws-cdk:subnet-type
          Value: Isolated
        - Key: Name
          Value: test/vpc/IsolatedSubnet1
      VpcId:
        Ref: vpcA2121C38
    Metadata:
      aws:cdk:path: test/vpc/IsolatedSubnet1/Subnet
  vpcIsolatedSubnet1RouteTable0D6B2D3D:
    Type: AWS::EC2::RouteTable
    Properties:
      Tags:
        - Key: Name
          Value: test/vpc/IsolatedSubnet1
      VpcId:
        Ref: vpcA2121C38
    Metadata:
      aws:cdk:path: test/vpc/IsolatedSubnet1/RouteTable
  vpcIsolatedSubnet1RouteTableAssociation172210D4:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId:
        Ref: vpcIsolatedSubnet1RouteTable0D6B2D3D
      SubnetId:
        Ref: vpcIsolatedSubnet1Subnet8B28CEB3
    Metadata:
      aws:cdk:path: test/vpc/IsolatedSubnet1/RouteTableAssociation
  vpcIsolatedSubnet2Subnet2C6B375C:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone:
        Fn::Select:
          - 1
          - Fn::GetAZs: ""
      CidrBlock: 10.0.4.0/22
      MapPublicIpOnLaunch: false
      Tags:
        - Key: aws-cdk:subnet-name
          Value: Isolated
        - Key: aws-cdk:subnet-type
          Value: Isolated
        - Key: Name
          Value: test/vpc/IsolatedSubnet2
      VpcId:
        Ref: vpcA2121C38
    Metadata:
      aws:cdk:path: test/vpc/IsolatedSubnet2/Subnet
  vpcIsolatedSubnet2RouteTable3455CBFC:
    Type: AWS::EC2::RouteTable
    Properties:
      Tags:
        - Key: Name
          Value: test/vpc/IsolatedSubnet2
      VpcId:
        Ref: vpcA2121C38
    Metadata:
      aws:cdk:path: test/vpc/IsolatedSubnet2/RouteTable
  vpcIsolatedSubnet2RouteTableAssociation8A8FAF70:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId:
        Ref: vpcIsolatedSubnet2RouteTable3455CBFC
      SubnetId:
        Ref: vpcIsolatedSubnet2Subnet2C6B375C
    Metadata:
      aws:cdk:path: test/vpc/IsolatedSubnet2/RouteTableAssociation
  vpcIGWE57CBDCA:
    Type: AWS::EC2::InternetGateway
    Properties:
      Tags:
        - Key: Name
          Value: test/vpc
    Metadata:
      aws:cdk:path: test/vpc/IGW
  vpcVPCGW7984C166:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      InternetGatewayId:
        Ref: vpcIGWE57CBDCA
      VpcId:
        Ref: vpcA2121C38
    Metadata:
      aws:cdk:path: test/vpc/VPCGW
  CDKMetadata:
    Type: AWS::CDK::Metadata
    Properties:
      Analytics: v2:deflate64:H4sIAAAAAAAA/02PTQ+CMAyGf4v3MYXExCvhYLwZMFzNGDWWj85sHcQQ/rtDSfDUt0+bp2ki4/gkDzs1ukjXbdRhJaeClW5FQHfQiZzKlxbZg8prJq4WB8VQ+IqAF7il3HiGm6o62PjGUueMRsVoaBlfiMGGhXOQjeq96tcu5XD/2QPxLHJwxlv9df7nzFCNi20WZGqQjdsP4ZH4GH5pHGJkPTH2IPNf/QDK5AK06AAAAA==
    Metadata:
      aws:cdk:path: test/CDKMetadata/Default
    Condition: CDKMetadataAvailable

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.118.0 (build a40f2ec)

Framework Version

No response

Node.js Version

Node.js v18.15.0

OS

Osx

Language

TypeScript

Language Version

No response

Other information

No response

[pahud]

Yes it makes sense to me. Thanks for the report.

[github-actions]

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