def subnet_ids
      resp = ec2.describe_subnets(filters: [
        {name: "vpc-id", values: [vpc_id]}
      ])
      resp.subnets.map(&:subnet_id).sort
    end
def subnet_ids
      resp = ec2.describe_subnets(filters: [
        {name: "vpc-id", values: [vpc_id]}
      ])
      resp.subnets.map(&:subnet_id).sort
    end
all subnets