simplify packer groups

Author: sjpb

.github/workflows/nightlybuild.yml

@@ -31,7 +31,7 @@ jobs:
           - ["update", "ofed", "cuda"]
         exclude:
           - source_image_name: Rocky-8-GenericCloud-Base-8.9-20231119.0.x86_64.qcow2
-            inventory_groups: ["update", "ofed", "cuda"]
+            inventory_groups: 'update,ofed,cuda'
     env:
       ANSIBLE_FORCE_COLOR: True
       OS_CLOUD: openstack
@@ -89,7 +89,7 @@ jobs:
           -var source_image_name=${{ matrix.source_image_name }} \
           -var image_name_prefix=rocky-${{ matrix.os_version }} \
           -var image_name_suffix=${{ env.IMAGE_NAME_SUFFIX }} \
-          -var 'inventory_groups=${{ toJSON(matrix.inventory_groups) }}' \
+          -var inventory_groups=${{ matrix.inventory_groups }} \
           openstack.pkr.hcl
         env:
           PACKER_LOG: '1'

packer/openstack.pkr.hcl

@@ -138,7 +138,8 @@ variable "metadata" {
 }
 
 variable "inventory_groups" {
-  type = list(string)
+  type = string
+  description = "comma-separated list of inventory groups, in addition to 'builder'"
   default = []
 }
 
@@ -157,6 +158,7 @@ variable "inventory_groups" {
 variable "image_name_prefix" {
   type = string
   description = "Prefix for built image names"
+  # TODO: maybe we can just make this default to the first two parts of the source image name?
   default = "openhpc"
 }
 
@@ -171,7 +173,7 @@ source "openstack" "openhpc" {
   flavor = var.flavor
   use_blockstorage_volume = var.use_blockstorage_volume
   volume_type = var.volume_type
-  volume_size = contains(var.inventory_groups, "cuda") ? var.volume_size_cuda : var.volume_size
+  volume_size = contains(split(",", var.inventory_groups), "cuda") ? var.volume_size_cuda : var.volume_size
   metadata = var.metadata
   instance_metadata = {ansible_init_disable = "true"}
   networks = var.networks
@@ -206,7 +208,7 @@ build {
 
   provisioner "ansible" {
     playbook_file = "${var.repo_root}/ansible/fatimage.yml"
-    groups = concat(["builder"], var.inventory_groups)
+    groups = concat(["builder"], split(",", var.inventory_groups))
     keep_inventory_file = true # for debugging
     use_proxy = false # see https://www.packer.io/docs/provisioners/ansible#troubleshooting
     extra_arguments = [