Migrate from v4 to v5

There are two smaller breaking changes:


A new mandatory parameter was added: ParentVPCStack.

If you want to migrate stacks based on opertions/backup-dynamodb.yaml, you have to create a VPC stack based on vpc/vpc-*azs.yaml and pass the name of the newly created vpc stack as the parameter ParentVPCStack. You can also use an existing vpc stack.


The auto scaling rules have changed and new parameters where added (all with default values). The cluster now scales based on a new metric: SchedulableContainers. Scaling based on SchedulableContainers is described in detail here: http://garbe.io/blog/2017/04/12/a-better-solution-to-ecs-autoscaling/

If you want to migrate stacks based on ecs/cluster.yaml, you have to check your ECS task definitions and look for the highest memory and cpu reservation and set the new parameters ContainerMaxMemory and ContainerMaxCPU to those values.