* Replace v0.11 bracket type hints with Terraform v0.12 list expressions
* Use expression syntax instead of interpolated strings, where suggested
* Update AWS tutorial and worker pools documentation
* Define Terraform and plugin version requirements in versions.tf
* Require aws ~> 2.7 to support Terraform v0.12
* Require ct ~> 0.3.2 to support Terraform v0.12
* AWS and Google Cloud make use of auto-scaling groups
and managed instance groups, respectively. As such, the
kubeconfig is already held in cloud user-data
* Controller instances are provisioned with a kubeconfig
from user-data. Its redundant to use a Terraform remote
file copy step for the kubeconfig.
* ELB distributing load across controllers is no longer the mechanism
used to SSH to instances to distribute secrets
* Focus the ELB on load balancing across apiserver and edit the HTTP
health check to an SSL:443 check
* Change controllers ASG to heterogeneous EC2 instances
* Create DNS records for each controller's private IP for etcd
* Change etcd to run on-host, across controllers (etcd-member.service)
* Reduce time to bootstrap a cluster
* Deprecate self-hosted-etcd on the AWS platform
