Improve modular design

[analytically]

This is an example of how to setup an entire cluster including subnets and VPC. It'd be easier if this was a truer module, as eg. https://github.com/terraform-aws-modules/terraform-aws-eks or https://github.com/terraform-aws-modules/terraform-aws-rds-aurora.

[rjeczalik]

Hey @analytically! What do you mean by “truer”, what should it do instead?

[analytically]

Eg. I'd love it if I could do something like:

module "scylladb" {
  source                          = "https://github.com/rjeczalik/terraform-aws-scylla/"
  name                            = "test-scylladb-cluster"

  vpc_id                          = "vpc-12345678"
  subnets                         = ["subnet-12345678", "subnet-87654321"]

  instance_type = "m5.large"
  cluster_count = 3
  key_name = "scylladb-key"

  allowed_security_groups         = ["sg-12345678"]
  storage_encrypted = true
  cluster_broadcast = "public"

  tags                            = {
    Environment = "test"
    Terraform   = "true"
  }
}