aws-ec2: Subnet L2 Construct does not support outpostArn and Vpc L2 Construct does not support outpost specific networking.

[RyanFrench]

Describe the feature

It is currently not possible to deploy a customer infrastructure onto an Outpost subnet using an L2 construct (aka ec2.Subnet). In addition, it is not possible to create a L2 Vpc using SubnetSelection if an Outpost subnet deployment is required.

Use Case

Automated CDK-based deployment of infrastructure that includes requirement for Outpost-based subnets, and allow developers to leverage the L2 VPC construct to deploy infrastructure that configures a VPC with Subnets deployed to an Outpost, with the VPC/Outpost association automatically created, and allow developers to set default routes via the Local Gateway.

Proposed Solution

The proposed solution is as follows:
• Add outpostArn to L2 Subnet construct
• Add the ability to create a VPC with SubnetSelection specific to outpost
• Add the ability to specify a local gateway (LGW) as part of the SubnetSelection for qualifying outpost subnet types.

example:

  const vpcCidr = this.node.tryGetContext("vpcCidr");
  const outpostAvailabilityZone = this.node.tryGetContext("outpostAvailabilityZone");
  const outpostArn = this.node.tryGetContext("outpostArn");
  const localGatewayId = this.node.tryGetContext("localGatewayId");
  const localGatewayRouteTableId = this.node.tryGetContext("localGatewayRouteTableId");
  new ec2.Vpc(this, "OutpostVPC", {
      cidr: vpcCidr,
      maxAzs: 2,
      localGatewayRouteTableIds: [localGatewayRouteTableId],
      subnetConfiguration: [
          {
              cidrMask: 26,
              name: "Public",
              subnetType: ec2.SubnetType.PUBLIC,
          },
          {
              cidrMask: 26,
              name: "Private",
              subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS,
          },
          {
              cidrMask: 26,
              name: "OutpostPublic",
              outpostArn,
              outpostAvailabilityZone: outpostAvailabilityZone,
              outpostDefaultRoute: ec2.OutpostDefaultRoute.ON_PREMISE,
              localGatewayId: localGatewayId,
              subnetType: ec2.SubnetType.PUBLIC_OUTPOST,
          },
          {
              cidrMask: 26,
              name: "OutpostPrivate",
              outpostArn,
              outpostAvailabilityZone: outpostAvailabilityZone,
              outpostDefaultRoute: ec2.OutpostDefaultRoute.ON_PREMISE,
              localGatewayId: localGatewayId,
              subnetType: ec2.SubnetType.PRIVATE_OUTPOST_WITH_EGRESS,
          },
      ],
  });

Other Information

#17838

While we considered building our own L2 Construct, this would require considerable effort to replicate the current logic around defining subnet CIDRs, adding NAT/Internet gateways, and would result in duplication of existing code.

We have implemented the proposed solution and will raise this as a PR.

@gffloodg

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.179.0

Environment details (OS name and version, etc.)

macOS Sequoia 15.3.1

[ashishdhingra]

Similar reported issue #17838 which got auto-closed due to staleness.