optional home vol using vol size

Author: sjpb

environments/skeleton/{{cookiecutter.environment}}/tofu/control.tf

@@ -1,5 +1,9 @@
 locals {
-  control_volumes = concat([openstack_blockstorage_volume_v3.state], var.home_volume_size > 0 ? [openstack_blockstorage_volume_v3.home][0] : [])
+  control_volumes = concat(
+    [openstack_blockstorage_volume_v3.state],
+    # convert map to list:
+    [for v in data.openstack_blockstorage_volume_v3.home: v]
+  )
   nodename = templatestring(
     var.cluster_nodename_template,
     {

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

@@ -119,6 +119,11 @@ variable "state_volume_size" {
     default = 150 # GB
 }
 
+/* variable "state_volume_mode" {
+    type = string
+    description = "Whether to "
+}
+ */
 variable "state_volume_type" {
     type = string
     description = "Type of state volume, if not default type"
@@ -127,8 +132,11 @@ variable "state_volume_type" {
 
 variable "home_volume_size" {
     type = number
-    description = "Size of state volume on control node, in GB"
-    default = 100 # GB, 0 means no home volume
+    description = <<-EOT
+        Size of state volume on control node, in GB. If zero, a volume with the
+        name $cluster_name-home must already exist unless home_volume_enabled = false
+    EOT
+    default = 100
 }
 
 variable "home_volume_type" {
@@ -137,6 +145,12 @@ variable "home_volume_type" {
     description = "Type of home volume, if not default type"
 }
 
+variable "home_volume_enabled" {
+    type = bool
+    default = true
+    description = "Whether to use a home volume"
+}
+
 variable "vnic_types" {
     type = map(string)
     description = <<-EOT

environments/skeleton/{{cookiecutter.environment}}/tofu/volumes.tf

@@ -7,10 +7,39 @@ resource "openstack_blockstorage_volume_v3" "state" {
 
 resource "openstack_blockstorage_volume_v3" "home" {
 
+    # NB: Changes CANNOT be made to this resource's "address"
+    # i.e. (label or for_each key)
+    # else existing clusters may get home volumes deleted and recreated!
+
     count = var.home_volume_size > 0 ? 1 : 0
 
     name = "${var.cluster_name}-home"  # last word used to label filesystem
     description = "Home for control node"
     size = var.home_volume_size
     volume_type = var.home_volume_type
 }
+
+data "openstack_blockstorage_volume_v3" "home" {
+
+/*  May or may not have a volume, depending on home_volume_enabled, so this
+    has to use for_each.
+
+    For the case where we use the above provisioned volume resource, we need
+    to create a depenency on it to avoid a race.
+
+    The logic is:
+    - If not home_volume_enabled, there is no volume
+    - Else if home_volume_size > 0 - use the provisioned volume resource
+    - Else find an existing volume with the specified name
+*/
+    
+    for_each =  toset(
+                    (var.home_volume_enabled) ? (
+                        (var.home_volume_size > 0) ? 
+                            [for v in openstack_blockstorage_volume_v3.home: v.name] :
+                                ["${var.cluster_name}-home"]
+                    ) : []
+                )
+
+    name = each.key
+}