How do I delete an ECS capacity provider which is in-use? - amazon-web-services

Question

I'm using CDK to set up an application backed by ECS. My stack is created successfully, but when I run cdk destroy the tear-down fails with the following error:
7:06:03 AM | DELETE_FAILED | AWS::ECS::ClusterCapacityProviderAssociations | sd-cluster/sd-cluster
Resource handler returned message: "The specified capacity provider is in use and cannot be removed. (Service: AmazonECS; Status Code: 400; Error Code: ResourceInUseException; Request ID:
f76555d1-5dc0-47b7-ba65-b65529c8b999; Proxy: null)" (RequestToken: 00531a51-2d95-aef9-77cd-3e06714c78b3, HandlerErrorCode: null)
I would assume obviously this is because my capacity provider is backed by an ASG (autoscaling group) which has an instance running, and there is a task currently running in my cluster.
The ASG is also defined within the stack.
But then how can I tear down this stack without manually going to the console and setting the running instances to zero?

Answer 1

This is a known issue in CDK - here's the issue on GitHub.
I included a workaround in the comments, here it is in Python:
#jsii.implements(cdk.IAspect)
class HotfixCapacityProviderDependencies:
# Add a dependency from capacity provider association to the cluster
# and from each service to the capacity provider association
def visit(self, node: IConstruct) -> None:
if type(node) is ecs.Ec2Service:
children = node.cluster.node.find_all()
for child in children:
if type(child) is ecs.CfnClusterCapacityProviderAssociations:
child.node.add_dependency(node.cluster)
node.node.add_dependency(child)
You would use it just as any other aspect:
# in the stack
Aspects.of(self).add(HotfixCapacityProviderDependencies())