Can AWS CDK load a pre-existing stack using an ARN? i.e. const stack = Stack.fromArn(...);

Question

Goal: I need to create an AWS ManagedPolicy that contains ALLOW permissions for API actions on resources created in a pre existing stack. No I cannot modify the existing stack template and simply add a policy to it. I need to create a new stack that deploys a policy that enables actions on the existing stacks resources

Solution: Create a CDK project to generate and deploy this policy stack. Within this CDK project I want to load the existing stack and iterate over its resources adding permissions to my new stack's policy.

Problem: I don't see any way to load an existing stack in CDK. I was hunting around for a "Stack.fromArn(...)" but don't see anything even similar.

Question: Is there some obsucre way to do this? Or is it simply not supported?

Answer 1

I did not tried it, however it looks like if you can access/lookup at least one construct from the existing stack, you can use the method Stack.of(construct) https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_core.Stack.html#static-ofconstruct to lookup the first stack scope in which the construct is defined. Not sure however how you could iterate resources in the looked up stack construct.

It might be not be the best answer, however one option could be to export the outputs for resources in existing stack which you want to include in the policy, and import these values in the new stack where you create the policy.