Add disk_iops variable for AWS

* Setting disk_iops is required for disk_type io1
* https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html#EBSVolumeTypes

aws/container-linux/kubernetes/workers/variables.tf

@@ -52,6 +52,12 @@ variable "disk_type" {
   description = "Type of the EBS volume (e.g. standard, gp2, io1)"
 }
 
+variable "disk_iops" {
+  type        = "string"
+  default     = "0"
+  description = "IOPS of the EBS volume (required for io1)"
+}
+
 variable "spot_price" {
   type        = "string"
   default     = ""

aws/container-linux/kubernetes/workers/workers.tf

@@ -52,6 +52,7 @@ resource "aws_launch_configuration" "worker" {
   root_block_device {
     volume_type = "${var.disk_type}"
     volume_size = "${var.disk_size}"
+    iops        = "${var.disk_iops}"
   }
 
   # network