data "aws_vpc" "myvpc" {

  tags = {
    Name = "demovpc"
  }

}

resource "aws_subnet" "demosubnet" {

  vpc_id     = "${data.aws_vpc.myvpc.id}"
  cidr_block = "${var.subnet_cidr_range}"
  tags = {
           Name = "demosubnet"
  }
}