Interesting that you say you worry about re-creating the cluster from scratch because I've experienced exactly the opposite. Our EKS cluster required so many operations outside CloudFormation to configure access control, add-ons, metrics server, ENABLE_PREFIX_DELEGATION, ENABLE_POD_ENI... It would be a huge risk to rebuild the EKS cluster. And applications hosted there are not independent because of these factors. It makes me very anxious working on the EKS cluster. Yes you can pay an extra $70/month to have a dev cluster, but it will never be equal to prod.

On the other hand, I was able to spin up an entire ECS cluster in a few minutes time with no manual operations and entirely within CloudFormation. ECS costs nothing extra, so creating multiple clusters is very reasonable, though separate clusters would impact packing efficiency. The applications can be fully independent.

> ECS has weird limits on how many containers you can run on one instance

Interesting. With ECS it says for c5.large the task limit is 2 with without trunking, 10 with.

With EKS

    $ ./max-pods-calculator.sh --instance-type c5.large --cni-version 1.12.6
    29
    $ ./max-pods-calculator.sh --instance-type c5.large --cni-version 1.12.6 --cni-prefix-delegation-enabled
    110