Adding Support for 1.12

[christopherhein]

Description

closes #679

This adds support for deploying Amazon EKS with Kubernetes 1.12. Default is still set to 1.11 if you'd like to use this use:

apiVersion: eksctl.io/v1alpha4
kind: ClusterConfig
metadata:
  name: <name>
  region: us-west-2
  version: "1.12"

or:

eksctl create cluster --name <name> --version 1.12

Checklist

• Code compiles correctly (i.e make build)
• Added tests that cover your change (if possible)
• All unit tests passing (i.e. make test)
• All integration tests passing (i.e. make integration-test)
• Added/modified documentation as required (such as the README.md, and examples directory)
• Added yourself to the humans.txt file

[errordeveloper]

discovering the available control plane version

I'm not aware of one, I'd be very keen to see it!

matching AMI versions?

We have make generate-ami, so that part is automated and we can improve that a bit more also.

[whereisaaron]

Thanks @errordeveloper. Sounds like that is a 'no'! There is an 'auto' option for AMIs maybe we could speculatively at '1.13' and '1.14 'to eksctl right now, and just report the error until it starts working 😄