vpc-export-import

AWS CDK Construct - export VPC from one stack, import to another

Unlike AWS CDK Constructs like DynamoDB, AWS did not provide the ability to easily export a VPC from one stack and import it in another. You can do it, but it's complicated, not documented anywhere, and makes your code messy. This Construct was designed to solve that problem.

Why would one want to export and import a VPC? Best practices. If for some reason you have to destory part of your application to redeploy it, you shouldn't destroy your VPCs (or your databases, or...). In other words stacks instances should be small and modular. Just like any good code or deployment.

Sure, you could manually create your VPCs and hard-code references to them, but this makes automatic creation of sandboxes very difficult or impossible, and isn't a very good practice in general.

Object Structure of a VPC

per the CDK object model, which mirrors that of the CFT and thus the underlying objects in AWS.

    VPC --- AvailabilityZones []
        --- Subnets (3 types) []
            --- RouteTables []
        --- vpnGatewayId
        --- vcpCidrBlock 
        --- ...

If you don't export the IDs of every one of these items and import them, you canmot recreate the VPC without warnings, subtle failures in other entities such as EFS and Lambda, or outright failures. There are no working examples, AFAICT, of doing so. Now, there is.

Usage

Anywhere you want to export a VPC from its and all its associated components from its creation Stack and import the VPC and its associated components into another Stack.

Module Usage

1. Add Module:

    npm install --save cdk-vpc-export-import
   

2. Import Statement:

    import VpcPortable from 'cdk-vpc-export-import';
   

3. General usage:

Use like any Ec2.Vpc. Call the function exportToStackOutput() to export from the stack, and in the stack that needs to use the vpc instance, call the static function importFromStackOutput(), which follows the similar pattern to other fromXXX() in the CDK. The object returned is a Ec2.Vpc that can be assigned as the network for a Lambda function, the network for an EFS file system, etc.

1. Use of global exports namespace on AWS

The stack exports functionality of CFT/CDK is used, which is a global namespace. The name is mangled with the stack name, the node.id of your VPC instance, and the names of the fields. If for some unlikely reason you get a collision or see problem please file an issue. It would be easy to implement options for alternative naming algorithms.

Testing And Development

See the corresponding repo for integration test, which is the only real way to test a VPC construct especially one that crosses stacks.