add block device prefix TF var

Author: sjpb

environments/skeleton/{{cookiecutter.environment}}/terraform/nodes.tf

@@ -114,11 +114,11 @@ resource "openstack_compute_instance_v2" "control" {
     fs_setup:
       - label: state
         filesystem: ext4
-        device: /dev/vdb
+        device: /dev/${var.block_device_prefix}b
         partition: auto
       - label: home
         filesystem: ext4
-        device: /dev/vdc
+        device: /dev/${var.block_device_prefix}c
         partition: auto
 
     mounts:

environments/skeleton/{{cookiecutter.environment}}/terraform/variables.tf

@@ -49,6 +49,12 @@ variable "environment_root" {
     description = "Path to environment root, automatically set by activate script"
 }
 
+variable "block_device_prefix" {
+    type = string
+    description = "Prefix for block device names"
+    default = "vd"
+}
+
 variable "state_dir" {
     type = string
     description = "Path to state directory on control node"