allow for volume-backed instances and use for CI on SMS

Author: sjpb

environments/.stackhpc/terraform/ARCUS.tfvars

@@ -3,3 +3,4 @@ cluster_subnet = "WCDC-iLab-60"
 vnic_type = "normal"
 control_node_flavor = "vm.ska.cpu.general.quarter"
 other_node_flavor = "vm.ska.cpu.general.small"
+volume_backed_instances = false

environments/.stackhpc/terraform/SMS.tfvars

@@ -3,3 +3,4 @@ cluster_subnet = "stackhpc-ipv4-geneve-subnet"
 vnic_type = "direct"
 control_node_flavor = "general.v1.medium"
 other_node_flavor = "general.v1.tiny"
+volume_backed_instances = true

environments/.stackhpc/terraform/main.tf

@@ -10,12 +10,6 @@ variable "cluster_name" {
     description = "Name for cluster, used as prefix for resources - set by environment var in CI"
 }
 
-variable "create_nodes" {
-    description = "Whether to create nodes (servers) or just ports and other infra"
-    type = bool # can't use bool as want to pass from command-line
-    default = true
-}
-
 variable "cluster_image" {
     description = "single image for all cluster nodes - a convenience for CI"
     type = string
@@ -34,6 +28,8 @@ variable "control_node_flavor" {}
 
 variable "other_node_flavor" {}
 
+variable "volume_backed_instances" {}
+
 module "cluster" {
     source = "../../skeleton/{{cookiecutter.environment}}/terraform/"
 
@@ -68,7 +64,7 @@ module "cluster" {
         compute-2: "extra"
         compute-3: "extra"
     }
-    create_nodes = var.create_nodes
+    volume_backed_instances = var.volume_backed_instances
 
     environment_root = var.environment_root
     # Can reduce volume size a lot for short-lived CI clusters:

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

@@ -7,6 +7,18 @@ data "openstack_images_image_v2" "control" {
   name = var.control_node.image
 }
 
+data "openstack_images_image_v2" "login" {
+  for_each = var.login_nodes
+
+  name = each.value.image
+}
+
+data "openstack_images_image_v2" "compute" {
+  for_each = var.compute_nodes
+
+  name = lookup(var.compute_images, each.key, var.compute_types[each.value].image)
+}
+
 resource "openstack_networking_port_v2" "login" {
 
   for_each = toset(keys(var.login_nodes))
@@ -68,7 +80,7 @@ resource "openstack_networking_port_v2" "compute" {
 
 resource "openstack_compute_instance_v2" "control" {
 
-  for_each = var.create_nodes ? toset(["control"]) : toset([])
+  for_each = toset(["control"])
 
   name = "${var.cluster_name}-${each.key}"
   image_name = data.openstack_images_image_v2.control.name
@@ -79,7 +91,8 @@ resource "openstack_compute_instance_v2" "control" {
   block_device {
       uuid = data.openstack_images_image_v2.control.id
       source_type  = "image"
-      destination_type = "local"
+      destination_type = var.volume_backed_instances ? "volume" : "local"
+      volume_size = var.volume_backed_instances ? var.root_volume_size : null
       boot_index = 0
       delete_on_termination = true
   }
@@ -136,12 +149,24 @@ resource "openstack_compute_instance_v2" "control" {
 
 resource "openstack_compute_instance_v2" "login" {
 
-  for_each = var.create_nodes ? var.login_nodes : {}
+  for_each = var.login_nodes
 
   name = "${var.cluster_name}-${each.key}"
   image_name = each.value.image
   flavor_name = each.value.flavor
   key_pair = var.key_pair
+
+  dynamic "block_device" {
+    for_each = var.volume_backed_instances ? [1]: []
+    content {
+      uuid = data.openstack_images_image_v2.login[each.key].id
+      source_type  = "image"
+      destination_type = "volume"
+      volume_size = var.root_volume_size
+      boot_index = 0
+      delete_on_termination = true
+    }
+  }
 
   network {
     port = openstack_networking_port_v2.login[each.key].id
@@ -162,12 +187,24 @@ resource "openstack_compute_instance_v2" "login" {
 
 resource "openstack_compute_instance_v2" "compute" {
 
-  for_each = var.create_nodes ? var.compute_nodes : {}
+  for_each = var.compute_nodes
 
   name = "${var.cluster_name}-${each.key}"
   image_name = lookup(var.compute_images, each.key, var.compute_types[each.value].image)
   flavor_name = var.compute_types[each.value].flavor
   key_pair = var.key_pair
+
+  dynamic "block_device" {
+    for_each = var.volume_backed_instances ? [1]: []
+    content {
+      uuid = data.openstack_images_image_v2.compute[each.key].id
+      source_type  = "image"
+      destination_type = "volume"
+      volume_size = var.root_volume_size
+      boot_index = 0
+      delete_on_termination = true
+    }
+  }
 
   network {
     port = openstack_networking_port_v2.compute[each.key].id

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

@@ -109,8 +109,14 @@ variable "nonlogin_security_groups" {
     ]
 }
 
-variable "create_nodes" {
-    description = "Whether to create nodes (servers) or just ports and other infra"
-    type = bool # can't use bool as want to pass from command-line
-    default = true
+variable "volume_backed_instances" {
+    description = "Whether to use volumes for root disks"
+    type = bool
+    default = false
+}
+
+variable "root_volume_size" {
+    description = "Size of volume for root volumes if using volume backed instances, in Gb"
+    type = number
+    default = 40
 }