Package software.amazon.awscdk.services.ec2.alpha

@Stability(Experimental) package software.amazon.awscdk.services.ec2.alpha

Amazon VpcV2 Construct Library

---

cdk-constructs: Experimental

The APIs of higher level constructs in this module are experimental and under active development. They are subject to non-backward compatible changes or removal in any future version. These are not subject to the Semantic Versioning model and breaking changes will be announced in the release notes. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.

VpcV2

VpcV2 is a re-write of the ec2.Vpc construct. This new construct enables higher level of customization on the VPC being created. VpcV2 implements the existing IVpc, therefore, VpcV2 is compatible with other constructs that accepts IVpc (e.g. ApplicationLoadBalancer).

To create a VPC with both IPv4 and IPv6 support: 

 Stack stack = new Stack();
 VpcV2.Builder.create(this, "Vpc")
         .primaryAddressBlock(IpAddresses.ipv4("10.0.0.0/24"))
         .secondaryAddressBlocks(List.of(IpAddresses.amazonProvidedIpv6(SecondaryAddressProps.builder().cidrBlockName("AmazonProvidedIpv6").build())))
         .build();

VpcV2 does not automatically create subnets or allocate IP addresses, which is different from the Vpc construct.

SubnetV2

SubnetV2 is a re-write of the ec2.Subnet construct. This new construct can be used to add subnets to a VpcV2 instance: 

 Stack stack = new Stack();
 VpcV2 myVpc = VpcV2.Builder.create(this, "Vpc")
         .secondaryAddressBlocks(List.of(IpAddresses.amazonProvidedIpv6(SecondaryAddressProps.builder().cidrBlockName("AmazonProvidedIp").build())))
         .build();
 
 SubnetV2.Builder.create(this, "subnetA")
         .vpc(myVpc)
         .availabilityZone("us-east-1a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .ipv6CidrBlock(new IpCidr("2a05:d02c:25:4000::/60"))
         .subnetType(SubnetType.PRIVATE_ISOLATED)
         .build();

IP Addresses Management

By default VpcV2 uses 10.0.0.0/16 as the primary CIDR if none is defined. Additional CIDRs can be adding to the VPC via the secondaryAddressBlocks prop. The following example illustrates the different options of defining the address blocks: 

 Stack stack = new Stack();
 Ipam ipam = Ipam.Builder.create(this, "Ipam")
         .operatingRegion(List.of("us-west-1"))
         .build();
 IIpamPool ipamPublicPool = ipam.publicScope.addPool("PublicPoolA", PoolOptions.builder()
         .addressFamily(AddressFamily.IP_V6)
         .awsService(AwsServiceName.EC2)
         .locale("us-west-1")
         .publicIpSource(IpamPoolPublicIpSource.AMAZON)
         .build());
 ipamPublicPool.provisionCidr("PublicPoolACidrA", IpamPoolCidrProvisioningOptions.builder().netmaskLength(52).build());
 
 IIpamPool ipamPrivatePool = ipam.privateScope.addPool("PrivatePoolA", PoolOptions.builder()
         .addressFamily(AddressFamily.IP_V4)
         .build());
 ipamPrivatePool.provisionCidr("PrivatePoolACidrA", IpamPoolCidrProvisioningOptions.builder().netmaskLength(8).build());
 
 VpcV2.Builder.create(this, "Vpc")
         .primaryAddressBlock(IpAddresses.ipv4("10.0.0.0/24"))
         .secondaryAddressBlocks(List.of(IpAddresses.amazonProvidedIpv6(SecondaryAddressProps.builder().cidrBlockName("AmazonIpv6").build()), IpAddresses.ipv6Ipam(IpamOptions.builder()
                 .ipamPool(ipamPublicPool)
                 .netmaskLength(52)
                 .cidrBlockName("ipv6Ipam")
                 .build()), IpAddresses.ipv4Ipam(IpamOptions.builder()
                 .ipamPool(ipamPrivatePool)
                 .netmaskLength(8)
                 .cidrBlockName("ipv4Ipam")
                 .build())))
         .build();

Since VpcV2 does not create subnets automatically, users have full control over IP addresses allocation across subnets.

Routing

RouteTable is a new construct that allows for route tables to be customized in a variety of ways. For instance, the following example shows how a custom route table can be created and appended to a subnet: 

 VpcV2 myVpc = new VpcV2(this, "Vpc");
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .routeTable(routeTable)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .subnetType(SubnetType.PRIVATE_ISOLATED)
         .build();

Routes can be created to link subnets to various different AWS services via gateways and endpoints. Each unique route target has its own dedicated construct that can be routed to a given subnet via the Route construct. An example using the InternetGateway construct can be seen below: 

 Stack stack = new Stack();
 VpcV2 myVpc = new VpcV2(this, "Vpc");
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .subnetType(SubnetType.PRIVATE_ISOLATED)
         .build();
 
 InternetGateway igw = InternetGateway.Builder.create(this, "IGW")
         .vpc(myVpc)
         .build();
 Route.Builder.create(this, "IgwRoute")
         .routeTable(routeTable)
         .destination("0.0.0.0/0")
         .target(Map.of("gateway", igw))
         .build();

Alternatively, Routes can also be created via method addRoute in the RouteTable class. An example using the EgressOnlyInternetGateway construct can be seen below: Note: EgressOnlyInternetGateway can only be used to set up outbound IPv6 routing. 

 Stack stack = new Stack();
 VpcV2 myVpc = VpcV2.Builder.create(this, "Vpc")
         .primaryAddressBlock(IpAddresses.ipv4("10.1.0.0/16"))
         .secondaryAddressBlocks(List.of(IpAddresses.amazonProvidedIpv6(SecondaryAddressProps.builder()
                 .cidrBlockName("AmazonProvided")
                 .build())))
         .build();
 
 EgressOnlyInternetGateway eigw = EgressOnlyInternetGateway.Builder.create(this, "EIGW")
         .vpc(myVpc)
         .build();
 
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 
 routeTable.addRoute("EIGW", "::/0", Map.of("gateway", eigw));

Other route targets may require a deeper set of parameters to set up properly. For instance, the example below illustrates how to set up a NatGateway: 

 VpcV2 myVpc = new VpcV2(this, "Vpc");
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .subnetType(SubnetType.PRIVATE_ISOLATED)
         .build();
 
 NatGateway natgw = NatGateway.Builder.create(this, "NatGW")
         .subnet(subnet)
         .vpc(myVpc)
         .connectivityType(NatConnectivityType.PRIVATE)
         .privateIpAddress("10.0.0.42")
         .build();
 Route.Builder.create(this, "NatGwRoute")
         .routeTable(routeTable)
         .destination("0.0.0.0/0")
         .target(Map.of("gateway", natgw))
         .build();

It is also possible to set up endpoints connecting other AWS services. For instance, the example below illustrates the linking of a Dynamo DB endpoint via the existing ec2.GatewayVpcEndpoint construct as a route target: 

 Stack stack = new Stack();
 VpcV2 myVpc = new VpcV2(this, "Vpc");
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .subnetType(SubnetType.PRIVATE)
         .build();
 
 GatewayVpcEndpoint dynamoEndpoint = GatewayVpcEndpoint.Builder.create(this, "DynamoEndpoint")
         .service(GatewayVpcEndpointAwsService.DYNAMODB)
         .vpc(myVpc)
         .subnets(List.of(subnet))
         .build();
 Route.Builder.create(this, "DynamoDBRoute")
         .routeTable(routeTable)
         .destination("0.0.0.0/0")
         .target(Map.of("endpoint", dynamoEndpoint))
         .build();

VPC Peering Connection

VPC peering connection allows you to connect two VPCs and route traffic between them using private IP addresses. The VpcV2 construct supports creating VPC peering connections through the VPCPeeringConnection construct from the route module.

Peering Connection cannot be established between two VPCs with overlapping CIDR ranges. Please make sure the two VPC CIDRs do not overlap with each other else it will throw an error.

For more information, see What is VPC peering?.

The following show examples of how to create a peering connection between two VPCs for all possible combinations of same-account or cross-account, and same-region or cross-region configurations.

Note: You cannot create a VPC peering connection between VPCs that have matching or overlapping CIDR blocks

Case 1: Same Account and Same Region Peering Connection 

 Stack stack = new Stack();
 
 VpcV2 vpcA = VpcV2.Builder.create(this, "VpcA")
         .primaryAddressBlock(IpAddresses.ipv4("10.0.0.0/16"))
         .build();
 
 VpcV2 vpcB = VpcV2.Builder.create(this, "VpcB")
         .primaryAddressBlock(IpAddresses.ipv4("10.1.0.0/16"))
         .build();
 
 VPCPeeringConnection peeringConnection = vpcA.createPeeringConnection("sameAccountSameRegionPeering", VPCPeeringConnectionOptions.builder()
         .acceptorVpc(vpcB)
         .build());

Case 2: Same Account and Cross Region Peering Connection

There is no difference from Case 1 when calling createPeeringConnection. The only change is that one of the VPCs are created in another stack with a different region. To establish cross region VPC peering connection, acceptorVpc needs to be imported to the requestor VPC stack using fromVpcV2Attributes method. 

 App app = new App();
 
 Stack stackA = Stack.Builder.create(app, "VpcStackA").env(Environment.builder().account("000000000000").region("us-east-1").build()).build();
 Stack stackB = Stack.Builder.create(app, "VpcStackB").env(Environment.builder().account("000000000000").region("us-west-2").build()).build();
 
 VpcV2 vpcA = VpcV2.Builder.create(stackA, "VpcA")
         .primaryAddressBlock(IpAddresses.ipv4("10.0.0.0/16"))
         .build();
 
 VpcV2.Builder.create(stackB, "VpcB")
         .primaryAddressBlock(IpAddresses.ipv4("10.1.0.0/16"))
         .build();
 
 IVpcV2 vpcB = VpcV2.fromVpcV2Attributes(stackA, "ImportedVpcB", VpcV2Attributes.builder()
         .vpcId("MockVpcBid")
         .vpcCidrBlock("10.1.0.0/16")
         .region("us-west-2")
         .ownerAccountId("000000000000")
         .build());
 
 VPCPeeringConnection peeringConnection = vpcA.createPeeringConnection("sameAccountCrossRegionPeering", VPCPeeringConnectionOptions.builder()
         .acceptorVpc(vpcB)
         .build());

Case 3: Cross Account Peering Connection

For cross-account connections, the acceptor account needs an IAM role that grants the requestor account permission to initiate the connection. Create a new IAM role in the acceptor account using method createAcceptorVpcRole to provide the necessary permissions.

Once role is created in account, provide role arn for field peerRoleArn under method createPeeringConnection 

 Stack stack = new Stack();
 
 VpcV2 acceptorVpc = VpcV2.Builder.create(this, "VpcA")
         .primaryAddressBlock(IpAddresses.ipv4("10.0.0.0/16"))
         .build();
 
 Role acceptorRoleArn = acceptorVpc.createAcceptorVpcRole("000000000000");

After creating an IAM role in the acceptor account, we can initiate the peering connection request from the requestor VPC. Import accpeptorVpc to the stack using fromVpcV2Attributes method, it is recommended to specify owner account id of the acceptor VPC in case of cross account peering connection, if acceptor VPC is hosted in different region provide region value for import as well. The following code snippet demonstrates how to set up VPC peering between two VPCs in different AWS accounts using CDK: 

 Stack stack = new Stack();
 
 IVpcV2 acceptorVpc = VpcV2.fromVpcV2Attributes(this, "acceptorVpc", VpcV2Attributes.builder()
         .vpcId("vpc-XXXX")
         .vpcCidrBlock("10.0.0.0/16")
         .region("us-east-2")
         .ownerAccountId("111111111111")
         .build());
 
 String acceptorRoleArn = "arn:aws:iam::111111111111:role/VpcPeeringRole";
 
 VpcV2 requestorVpc = VpcV2.Builder.create(this, "VpcB")
         .primaryAddressBlock(IpAddresses.ipv4("10.1.0.0/16"))
         .build();
 
 VPCPeeringConnection peeringConnection = requestorVpc.createPeeringConnection("crossAccountCrossRegionPeering", VPCPeeringConnectionOptions.builder()
         .acceptorVpc(acceptorVpc)
         .peerRoleArn(acceptorRoleArn)
         .build());

Route Table Configuration

After establishing the VPC peering connection, routes must be added to the respective route tables in the VPCs to enable traffic flow. If a route is added to the requestor stack, information will be able to flow from the requestor VPC to the acceptor VPC, but not in the reverse direction. For bi-directional communication, routes need to be added in both VPCs from their respective stacks.

For more information, see Update your route tables for a VPC peering connection. 

 Stack stack = new Stack();
 
 VpcV2 acceptorVpc = VpcV2.Builder.create(this, "VpcA")
         .primaryAddressBlock(IpAddresses.ipv4("10.0.0.0/16"))
         .build();
 
 VpcV2 requestorVpc = VpcV2.Builder.create(this, "VpcB")
         .primaryAddressBlock(IpAddresses.ipv4("10.1.0.0/16"))
         .build();
 
 VPCPeeringConnection peeringConnection = requestorVpc.createPeeringConnection("peeringConnection", VPCPeeringConnectionOptions.builder()
         .acceptorVpc(acceptorVpc)
         .build());
 
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(requestorVpc)
         .build();
 
 routeTable.addRoute("vpcPeeringRoute", "10.0.0.0/16", Map.of("gateway", peeringConnection));

This can also be done using AWS CLI. For more information, see create-route. 

 # Add a route to the requestor VPC route table
 aws ec2 create-route --route-table-id rtb-requestor --destination-cidr-block 10.0.0.0/16 --vpc-peering-connection-id pcx-xxxxxxxx
 
 # For bi-directional add a route in the acceptor vpc account as well
 aws ec2 create-route --route-table-id rtb-acceptor --destination-cidr-block 10.1.0.0/16 --vpc-peering-connection-id pcx-xxxxxxxx

Deleting the Peering Connection

To delete a VPC peering connection, use the following command: 

 aws ec2 delete-vpc-peering-connection --vpc-peering-connection-id pcx-xxxxxxxx

For more information, see Delete a VPC peering connection.

Adding Egress-Only Internet Gateway to VPC

An egress-only internet gateway is a horizontally scaled, redundant, and highly available VPC component that allows outbound communication over IPv6 from instances in your VPC to the internet, and prevents the internet from initiating an IPv6 connection with your instances.

For more information see Enable outbound IPv6 traffic using an egress-only internet gateway.

VpcV2 supports adding an egress only internet gateway to VPC using the addEgressOnlyInternetGateway method.

By default, this method sets up a route to all outbound IPv6 address ranges, unless a specific destination is provided by the user. It can only be configured for IPv6-enabled VPCs. The Subnets parameter accepts a SubnetFilter, which can be based on a SubnetType in VpcV2. A new route will be added to the route tables of all subnets that match this filter. 

 Stack stack = new Stack();
 VpcV2 myVpc = VpcV2.Builder.create(this, "Vpc")
         .primaryAddressBlock(IpAddresses.ipv4("10.1.0.0/16"))
         .secondaryAddressBlocks(List.of(IpAddresses.amazonProvidedIpv6(SecondaryAddressProps.builder()
                 .cidrBlockName("AmazonProvided")
                 .build())))
         .build();
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .ipv6CidrBlock(new IpCidr("2001:db8:1::/64"))
         .subnetType(SubnetType.PRIVATE)
         .build();
 
 myVpc.addEgressOnlyInternetGateway(EgressOnlyInternetGatewayOptions.builder()
         .subnets(List.of(SubnetSelection.builder().subnetType(SubnetType.PRIVATE).build()))
         .destination("::/60")
         .build());

Adding NATGateway to the VPC

A NAT gateway is a Network Address Translation (NAT) service.You can use a NAT gateway so that instances in a private subnet can connect to services outside your VPC but external services cannot initiate a connection with those instances.

For more information, see NAT gateway basics.

When you create a NAT gateway, you specify one of the following connectivity types:

Public – (Default): Instances in private subnets can connect to the internet through a public NAT gateway, but cannot receive unsolicited inbound connections from the internet

Private: Instances in private subnets can connect to other VPCs or your on-premises network through a private NAT gateway.

To define the NAT gateway connectivity type as ConnectivityType.Public, you need to ensure that there is an IGW(Internet Gateway) attached to the subnet's VPC. Since a NATGW is associated with a particular subnet, providing subnet field in the input props is mandatory.

Additionally, you can set up a route in any route table with the target set to the NAT Gateway. The function addNatGateway returns a NATGateway object that you can reference later.

The code example below provides the definition for adding a NAT gateway to your subnet: 

 Stack stack = new Stack();
 VpcV2 myVpc = new VpcV2(this, "Vpc");
 RouteTable routeTable = RouteTable.Builder.create(this, "RouteTable")
         .vpc(myVpc)
         .build();
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .subnetType(SubnetType.PUBLIC)
         .build();
 
 myVpc.addInternetGateway();
 myVpc.addNatGateway(NatGatewayOptions.builder()
         .subnet(subnet)
         .connectivityType(NatConnectivityType.PUBLIC)
         .build());

Enable VPNGateway for the VPC

A virtual private gateway is the endpoint on the VPC side of your VPN connection.

For more information, see What is AWS Site-to-Site VPN?.

VPN route propagation is a feature in Amazon Web Services (AWS) that automatically updates route tables in your Virtual Private Cloud (VPC) with routes learned from a VPN connection.

To enable VPN route propogation, use the vpnRoutePropagation property to specify the subnets as an input to the function. VPN route propagation will then be enabled for each subnet with the corresponding route table IDs.

Additionally, you can set up a route in any route table with the target set to the VPN Gateway. The function enableVpnGatewayV2 returns a VPNGatewayV2 object that you can reference later.

The code example below provides the definition for setting up a VPN gateway with vpnRoutePropogation enabled: 

 Stack stack = new Stack();
 VpcV2 myVpc = new VpcV2(this, "Vpc");
 VPNGatewayV2 vpnGateway = myVpc.enableVpnGatewayV2(VPNGatewayV2Options.builder()
         .vpnRoutePropagation(List.of(SubnetSelection.builder().subnetType(SubnetType.PUBLIC).build()))
         .type(VpnConnectionType.IPSEC_1)
         .build());
 
 RouteTable routeTable = RouteTable.Builder.create(stack, "routeTable")
         .vpc(myVpc)
         .build();
 
 Route.Builder.create(stack, "route")
         .destination("172.31.0.0/24")
         .target(Map.of("gateway", vpnGateway))
         .routeTable(routeTable)
         .build();

Adding InternetGateway to the VPC

An internet gateway is a horizontally scaled, redundant, and highly available VPC component that allows communication between your VPC and the internet. It supports both IPv4 and IPv6 traffic.

For more information, see Enable VPC internet access using internet gateways.

You can add an internet gateway to a VPC using addInternetGateway method. By default, this method creates a route in all Public Subnets with outbound destination set to 0.0.0.0 for IPv4 and ::0 for IPv6 enabled VPC. Instead of using the default settings, you can configure a custom destinatation range by providing an optional input destination to the method.

The code example below shows how to add an internet gateway with a custom outbound destination IP range: 

 Stack stack = new Stack();
 VpcV2 myVpc = new VpcV2(this, "Vpc");
 
 SubnetV2 subnet = SubnetV2.Builder.create(this, "Subnet")
         .vpc(myVpc)
         .availabilityZone("eu-west-2a")
         .ipv4CidrBlock(new IpCidr("10.0.0.0/24"))
         .subnetType(SubnetType.PUBLIC)
         .build();
 
 myVpc.addInternetGateway(InternetGatewayOptions.builder()
         .ipv4Destination("192.168.0.0/16")
         .build());

Importing an existing VPC

You can import an existing VPC and its subnets using the VpcV2.fromVpcV2Attributes() method or an individual subnet using SubnetV2.fromSubnetV2Attributes() method.

Importing a VPC

To import an existing VPC, use the VpcV2.fromVpcV2Attributes() method. You'll need to provide the VPC ID, primary CIDR block, and information about the subnets. You can import secondary address as well created through IPAM, BYOIP(IPv4) or enabled through Amazon Provided IPv6. You must provide VPC Id and its primary CIDR block for importing it.

If you wish to add a new subnet to imported VPC, new subnet's IP range(IPv4) will be validated against provided secondary and primary address block to confirm that it is within the the range of VPC.

Here's an example of importing a VPC with only the required parameters 

 Stack stack = new Stack();
 
 IVpcV2 importedVpc = VpcV2.fromVpcV2Attributes(stack, "ImportedVpc", VpcV2Attributes.builder()
         .vpcId("mockVpcID")
         .vpcCidrBlock("10.0.0.0/16")
         .build());

In case of cross account or cross region VPC, its recommended to provide region and ownerAccountId so that these values for the VPC can be used to populate correct arn value for the VPC. If a VPC region and account ID is not provided, then region and account configured in the stack will be used. Furthermore, these fields will be referenced later while setting up VPC peering connection, so its necessary to set these fields to a correct value.

Below is an example of importing a cross region and cross acount VPC, VPC arn for this case would be 'arn:aws:ec2:us-west-2:123456789012:vpc/mockVpcID' 

 Stack stack = new Stack();
 
 //Importing a cross acount or cross region VPC
 IVpcV2 importedVpc = VpcV2.fromVpcV2Attributes(stack, "ImportedVpc", VpcV2Attributes.builder()
         .vpcId("mockVpcID")
         .vpcCidrBlock("10.0.0.0/16")
         .ownerAccountId("123456789012")
         .region("us-west-2")
         .build());

Here's an example of how to import a VPC with multiple CIDR blocks, IPv6 support, and different subnet types:

In this example, we're importing a VPC with:

  • A primary CIDR block (10.1.0.0/16)
  • One secondary IPv4 CIDR block (10.2.0.0/16)
  • Two secondary address using IPAM pool (IPv4 and IPv6)
  • VPC has Amazon-provided IPv6 CIDR enabled
  • An isolated subnet in us-west-2a
  • A public subnet in us-west-2b

 Stack stack = new Stack();
 
 IVpcV2 importedVpc = VpcV2.fromVpcV2Attributes(this, "ImportedVPC", VpcV2Attributes.builder()
         .vpcId("vpc-XXX")
         .vpcCidrBlock("10.1.0.0/16")
         .secondaryCidrBlocks(List.of(VPCCidrBlockattributes.builder()
                 .cidrBlock("10.2.0.0/16")
                 .cidrBlockName("ImportedBlock1")
                 .build(), VPCCidrBlockattributes.builder()
                 .ipv6IpamPoolId("ipam-pool-XXX")
                 .ipv6NetmaskLength(52)
                 .cidrBlockName("ImportedIpamIpv6")
                 .build(), VPCCidrBlockattributes.builder()
                 .ipv4IpamPoolId("ipam-pool-XXX")
                 .ipv4IpamProvisionedCidrs(List.of("10.2.0.0/16"))
                 .cidrBlockName("ImportedIpamIpv4")
                 .build(), VPCCidrBlockattributes.builder()
                 .amazonProvidedIpv6CidrBlock(true)
                 .build()))
         .subnets(List.of(SubnetV2Attributes.builder()
                 .subnetName("IsolatedSubnet2")
                 .subnetId("subnet-03cd773c0fe08ed26")
                 .subnetType(SubnetType.PRIVATE_ISOLATED)
                 .availabilityZone("us-west-2a")
                 .ipv4CidrBlock("10.2.0.0/24")
                 .routeTableId("rtb-0871c310f98da2cbb")
                 .build(), SubnetV2Attributes.builder()
                 .subnetId("subnet-0fa477e01db27d820")
                 .subnetType(SubnetType.PUBLIC)
                 .availabilityZone("us-west-2b")
                 .ipv4CidrBlock("10.3.0.0/24")
                 .routeTableId("rtb-014f3043098fe4b96")
                 .build()))
         .build());
 
 // You can now use the imported VPC in your stack
 
 // Adding a new subnet to the imported VPC
 SubnetV2 importedSubnet = SubnetV2.Builder.create(this, "NewSubnet")
         .availabilityZone("us-west-2a")
         .ipv4CidrBlock(new IpCidr("10.2.2.0/24"))
         .vpc(importedVpc)
         .subnetType(SubnetType.PUBLIC)
         .build();
 
 // Adding gateways to the imported VPC
 importedVpc.addInternetGateway();
 importedVpc.addNatGateway(NatGatewayOptions.builder().subnet(importedSubnet).build());
 importedVpc.addEgressOnlyInternetGateway();

You can add more subnets as needed by including additional entries in the isolatedSubnets, publicSubnets, or other subnet type arrays (e.g., privateSubnets).

Importing Subnets

You can also import individual subnets using the SubnetV2.fromSubnetV2Attributes() method. This is useful when you need to work with specific subnets independently of a VPC.

Here's an example of how to import a subnet: 

 SubnetV2.fromSubnetV2Attributes(this, "ImportedSubnet", SubnetV2Attributes.builder()
         .subnetId("subnet-0123456789abcdef0")
         .availabilityZone("us-west-2a")
         .ipv4CidrBlock("10.2.0.0/24")
         .routeTableId("rtb-0871c310f98da2cbb")
         .subnetType(SubnetType.PRIVATE_ISOLATED)
         .build());

By importing existing VPCs and subnets, you can easily integrate your existing AWS infrastructure with new resources created through CDK. This is particularly useful when you need to work with pre-existing network configurations or when you're migrating existing infrastructure to CDK.