cdk python making route table entries

Question

Is it possible to add route entries to a route table via cdk?

The way I tried is: using a vpc construct I tried to iterate over the public_subnets + private_subnets attributes lists to get the routeTables. But these return IRouteTable -- with which I can't seem to do any updates. Anyone know how to do it? Thanks.

Answer 1

You can able to solve this by instantiating new CloudFormation Route resources:

vpc.privateSubnets.forEach(({ routeTable: { routeTableId } }, index) => {
  new CfnRoute(stack, 'PrivateSubnetPeeringConnectionRoute' + index, {
    destinationCidrBlock: '10.0.0.0/16',
    routeTableId,
    vpcPeeringConnectionId: peeringConnection.ref,
  })
})

You will need to know the ID of the peering connection for those routes. In the example above, it's referenced as it's created in the same stack:

const peeringConnection = new CfnVPCPeeringConnection(
  stack,
  'PeeringConnection',
  {
    peerVpcId: peerVpc.vpcId,
    vpcId: vpc.vpcId,
  }
)

Consider [1] , [2] and [3] for more details

[1] https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-ec2.Vpc.html#static-from-wbr-vpc-wbr-attributesscope-id-attrs

[2] https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-ec2.Subnet.html#add-wbr-routeid-options

[3] https://qiita.com/is_ryo/items/66dfe6c4b6dda4bd1eeb

Answer 2

Turns out it's using the Subnet construct that you add routes with in cdk (using the add_route method). https://docs.aws.amazon.com/cdk/api/latest/python/aws_cdk.aws_ec2/Subnet.html