[bug] GPUs are not available in all availability zones

[schwichti]

I tried to manually add a GPU node group to an EKS cluster, but it appears that some instance types are not available in all availability zones (e.g. eu-central-1c). You can see the available availability zones in the Networking section here: https://eu-central-1.console.aws.amazon.com/ec2/home?region=eu-central-1#InstanceTypeDetails:instanceType=p3.2xlarge

Creation of the node group fails with the following error message:

Could not launch On-Demand Instances. Unsupported - Your requested instance type (p2.xlarge) is not 
supported in your requested Availability Zone (eu-central-1c). Please retry your request by not specifying 
an Availability Zone or choosing eu-central-1a, eu-central-1b. Launching EC2 instance failed.

Can be solved by excluding the unsupported zones from here: https://github.com/dspace-group/simphera-reference-architecture-aws/blob/main/locals.tf#L53