Support aws_availability_zones

[analytically]

See hashicorp/terraform#11482

data "aws_availability_zones" "available" {}

resource "aws_subnet" "public" {
  count = "${length(data.aws_availability_zones.available.id)}"
  availability_zone = "${data.aws_availability_zones.available.id[count.index]}"
}

[nyambati]

@analytically I think you can still use the module as is with aws_availability_zones. This module requires a list of azs to create subnets. You can supply that list to the module, here is an example.

module "vpc" {
...
  azs                = ["${data.aws_availability_zones.available.names}"]
...
}

I think the current setup makes the module more flexible providing more control on how many subnets you would like to create.

[analytically]

Thanks!