diff --git a/.github/workflows/fatimage.yml b/.github/workflows/fatimage.yml
index 947f9410f..e15937099 100644
--- a/.github/workflows/fatimage.yml
+++ b/.github/workflows/fatimage.yml
@@ -15,37 +15,26 @@ jobs:
   openstack:
     name: openstack-imagebuild
     concurrency:
-      group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.os_version }}-${{ matrix.build }} # to branch/PR + OS + build
+      group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.builds.label }}
       cancel-in-progress: true
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: false # allow other matrix jobs to continue even if one fails
       matrix: # build RL8+OFED, RL9+OFED, RL9+OFED+CUDA versions
-        os_version:
-          - RL8
-          - RL9
-        build:
-          - openstack.openhpc
-          - openstack.openhpc-cuda
-        exclude:
-          - os_version: RL8
-            build: openstack.openhpc-cuda
+        builds:
+          - label: openhpc-RL8-ofed
+            source_image_name: RL8-ofed
+            inventory_groups: 'control,login,compute'
+          - label: openhpc-RL9-ofed
+            source_image_name: RL9-ofed
+            inventory_groups: 'control,login,compute'
+          - label: openhpc-RL9-cuda
+            source_image_name: RL9-cuda
+            inventory_groups: 'control,login,compute'
     env:
       ANSIBLE_FORCE_COLOR: True
       OS_CLOUD: openstack
       CI_CLOUD: ${{ github.event.inputs.ci_cloud }}
-      SOURCE_IMAGES_MAP: |
-        {
-          "RL8": {
-            "openstack.openhpc": "rocky-latest-RL8",
-            "openstack.openhpc-cuda": "rocky-latest-cuda-RL8"
-          },
-          "RL9": {
-            "openstack.openhpc": "rocky-latest-RL9",
-            "openstack.openhpc-cuda": "rocky-latest-cuda-RL9"
-          }
-        }
-
     steps:
       - uses: actions/checkout@v2
 
@@ -79,6 +68,20 @@ jobs:
           . venv/bin/activate
           . environments/.stackhpc/activate
 
+      - name: Select branch-specific or latest nightly image
+        id: select_source_image
+        run: |
+          . venv/bin/activate
+          . environments/.stackhpc/activate
+          BRANCH=${{ github.ref_name }}
+          BRANCH_VERSION=${BRANCH//\//-} # replace '/' with '-' using bash parameter expansion
+          NIGHTLY_IMAGE_ID=$( \
+            openstack image show -c id -f value ${{ matrix.builds.source_image_name }}-${BRANCH_VERSION} || \
+            openstack image show -c id -f value ${{ matrix.builds.source_image_name }}-latest \
+          )
+          echo selected source_image $NIGHTLY_IMAGE_ID: $(openstack image show -c name -f value $NIGHTLY_IMAGE_ID)
+          echo "source_image_id=$NIGHTLY_IMAGE_ID" >> "$GITHUB_OUTPUT"
+      
       - name: Build fat image with packer
         id: packer_build
         run: |
@@ -88,15 +91,15 @@ jobs:
           cd packer/
           packer init .
 
-          PACKER_LOG=1 packer build \
+          packer build \
           -on-error=${{ vars.PACKER_ON_ERROR }} \
-          -only=${{ matrix.build }} \
           -var-file=$PKR_VAR_environment_root/${{ env.CI_CLOUD }}.pkrvars.hcl \
-          -var "source_image_name=${{ env.SOURCE_IMAGE }}" \
+          -var source_image=${{ steps.select_source_image.outputs.source_image_id }} \
+          -var image_name=${{ matrix.builds.label }} \
+          -var inventory_groups=${{ matrix.builds.inventory_groups }} \
           openstack.pkr.hcl
         env:
-          PKR_VAR_os_version: ${{ matrix.os_version }}
-          SOURCE_IMAGE: ${{ fromJSON(env.SOURCE_IMAGES_MAP)[matrix.os_version][matrix.build] }}
+          PACKER_LOG: '1'
 
       - name: Get created image names from manifest
         id: manifest
@@ -113,7 +116,7 @@ jobs:
       - name: Upload manifest artifact
         uses: actions/upload-artifact@v4
         with:
-          name: image-details-${{ matrix.build }}-${{ matrix.os_version }}
+          name: image-details-${{ matrix.builds.label }}
           path: |
             ./image-id.txt
             ./image-name.txt
diff --git a/.github/workflows/nightlybuild.yml b/.github/workflows/nightlybuild.yml
index 607dabd2e..5bdaa9999 100644
--- a/.github/workflows/nightlybuild.yml
+++ b/.github/workflows/nightlybuild.yml
@@ -1,3 +1,5 @@
+# NB: When run in a non-main branch (via workflow_dispatch), image scanning and distribution to other clouds does not happen
+# on the basis that in this case a fatimage must be built and will be scanned.
 name: Build nightly image
 on:
   workflow_dispatch:
@@ -14,34 +16,30 @@ on:
     - cron: '0 0 * * *'  # Run at midnight
 
 jobs:
-  openstack:
-    name: openstack-imagebuild
+  build:
+    name: nightly-imagebuild
     concurrency:
-      group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.os_version }}-${{ matrix.build }} # to branch/PR + OS + build
+      group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.builds.label }}
       cancel-in-progress: true
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: false # allow other matrix jobs to continue even if one fails
-      matrix: # build RL8, RL9, RL9+CUDA versions
-        os_version:
-          - RL8
-          - RL9
-        build:
-          - openstack.rocky-latest
-          - openstack.rocky-latest-cuda
-        exclude:
-          - os_version: RL8
-            build: openstack.rocky-latest-cuda
-
+      matrix:
+        builds:
+          - label: RL8-ofed
+            source_image_name: Rocky-8-GenericCloud-Base-8.9-20231119.0.x86_64.qcow2
+            inventory_groups: 'update,ofed'
+          - label: RL9-ofed
+            source_image_name: Rocky-9-GenericCloud-Base-9.4-20240523.0.x86_64.qcow2
+            inventory_groups: 'update,ofed'
+          - label: RL9-cuda
+            source_image_name: Rocky-9-GenericCloud-Base-9.4-20240523.0.x86_64.qcow2
+            inventory_groups: 'update,ofed,cuda'
     env:
       ANSIBLE_FORCE_COLOR: True
       OS_CLOUD: openstack
       CI_CLOUD: ${{ github.event.inputs.ci_cloud || vars.CI_CLOUD }}
-      SOURCE_IMAGES_MAP: |
-        {
-          "RL8": "Rocky-8-GenericCloud-Base-8.9-20231119.0.x86_64.qcow2",
-          "RL9": "Rocky-9-GenericCloud-Base-9.4-20240523.0.x86_64.qcow2"
-        }
+      IMAGE_VERSION: ${{ github.event_name == 'schedule' && 'latest' || github.ref_name	}}
 
     steps:
       - uses: actions/checkout@v2
@@ -85,18 +83,18 @@ jobs:
           cd packer/
           packer init .
 
-          PACKER_LOG=1 packer build \
+          packer build \
           -on-error=${{ vars.PACKER_ON_ERROR }} \
-          -only=${{ matrix.build }} \
           -var-file=$PKR_VAR_environment_root/${{ env.CI_CLOUD }}.pkrvars.hcl \
-          -var "source_image_name=${{ env.SOURCE_IMAGE }}" \
+          -var source_image_name=${{ matrix.builds.source_image_name }} \
+          -var image_name=${{ matrix.builds.label }} \
+          -var image_version=${{ env.IMAGE_VERSION }} \
+          -var inventory_groups=${{ matrix.builds.inventory_groups }} \
           openstack.pkr.hcl
-
         env:
-          PKR_VAR_os_version: ${{ matrix.os_version }}
-          SOURCE_IMAGE: ${{ fromJSON(env.SOURCE_IMAGES_MAP)[matrix.os_version] }}
+          PACKER_LOG: '1'
 
-      - name: Get created image names from manifest
+      - name: Get image info and ensure it can be used for subsequent builds
         id: manifest
         run: |
           . venv/bin/activate
@@ -105,8 +103,10 @@ jobs:
             sleep 5
           done
           IMAGE_NAME=$(openstack image show -f value -c name $IMAGE_ID)
+          echo image: ${IMAGE_NAME} ${IMAGE_ID}
           echo "image-name=${IMAGE_NAME}" >> "$GITHUB_OUTPUT"
           echo "image-id=$IMAGE_ID" >> "$GITHUB_OUTPUT"
+          openstack image unset --property signature_verified $IMAGE_ID
 
       - name: Delete old latest image
         run: |
@@ -122,9 +122,10 @@ jobs:
 
   upload:
     name: upload-nightly-targets
-    needs: openstack
+    needs: build
+    if: github.ref_name == 'main'
     concurrency:
-      group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.os_version }}-${{ matrix.image }}-${{ matrix.target_cloud }}
+      group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.builds.label }}-${{ matrix.target_cloud }}
       cancel-in-progress: true
     runs-on: ubuntu-22.04
     strategy:
@@ -134,21 +135,16 @@ jobs:
           - LEAFCLOUD
           - SMS
           - ARCUS
-        os_version:
-          - RL8
-          - RL9
-        image:
-          - rocky-latest
-          - rocky-latest-cuda
+        builds:
+          - image: RL8-ofed-latest
+          - image: RL9-ofed-latest
+          - image: RL9-cuda-latest
         exclude:
-          - os_version: RL8
-            image: rocky-latest-cuda
-          - target_cloud: LEAFCLOUD
+          - target_cloud: LEAFCLOUD # why?? Should this not be source_cloud/vars.CI_CLOUD
     env:
       OS_CLOUD: openstack
       SOURCE_CLOUD: ${{ github.event.inputs.ci_cloud || vars.CI_CLOUD }}
       TARGET_CLOUD: ${{ matrix.target_cloud }}
-      IMAGE_NAME: "${{ matrix.image }}-${{ matrix.os_version }}"
     steps:
       - uses: actions/checkout@v2
 
@@ -176,7 +172,7 @@ jobs:
         run: |
           . venv/bin/activate
           export OS_CLIENT_CONFIG_FILE=~/.config/openstack/source_clouds.yaml
-          openstack image save --file ${{ env.IMAGE_NAME }} ${{ env.IMAGE_NAME }}
+          openstack image save --file ${{ matrix.builds.image }} ${{ matrix.builds.image }}
         shell: bash
 
       - name: Upload to target cloud
@@ -184,8 +180,8 @@ jobs:
           . venv/bin/activate
           export OS_CLIENT_CONFIG_FILE=~/.config/openstack/target_clouds.yaml
 
-          openstack image create "${{ env.IMAGE_NAME }}" \
-            --file "${{ env.IMAGE_NAME }}" \
+          openstack image create "${{ matrix.builds.image }}" \
+            --file "${{ matrix.builds.image }}" \
             --disk-format qcow2 \
         shell: bash
 
@@ -194,9 +190,9 @@ jobs:
           . venv/bin/activate
           export OS_CLIENT_CONFIG_FILE=~/.config/openstack/target_clouds.yaml
 
-          IMAGE_COUNT=$(openstack image list --name ${{ env.IMAGE_NAME }} -f value -c ID | wc -l)
+          IMAGE_COUNT=$(openstack image list --name ${{ matrix.builds.image }} -f value -c ID | wc -l)
           if [ "$IMAGE_COUNT" -gt 1 ]; then
-            OLD_IMAGE_ID=$(openstack image list --sort created_at:asc --name "${{ env.IMAGE_NAME }}"  -f value -c ID | head -n 1)
+            OLD_IMAGE_ID=$(openstack image list --sort created_at:asc --name "${{ matrix.builds.image }}"  -f value -c ID | head -n 1)
             openstack image delete "$OLD_IMAGE_ID"
           else
             echo "Only one image exists, skipping deletion."
diff --git a/ansible/.gitignore b/ansible/.gitignore
index f6f5c5f4d..c8296cc8c 100644
--- a/ansible/.gitignore
+++ b/ansible/.gitignore
@@ -60,3 +60,5 @@ roles/*
 !roles/tuned/**
 !roles/lustre/
 !roles/lustre/**
+!roles/builder/
+!roles/builder/**
diff --git a/ansible/fatimage.yml b/ansible/fatimage.yml
index 7cad2dc59..0b0577289 100644
--- a/ansible/fatimage.yml
+++ b/ansible/fatimage.yml
@@ -207,8 +207,14 @@
   gather_facts: yes
   tags: finalise
   tasks:
-    - name: Cleanup image
-      import_tasks: cleanup.yml
+    - name: Carry out checks on image
+      import_role:
+        name: builder
+        tasks_from: checks.yml
+    - name: Finalise image
+      import_role:
+        name: builder
+        tasks_from: finalise.yml
 
     - name: Shutdown Packer VM
       community.general.shutdown:
diff --git a/ansible/roles/builder/defaults/main.yml b/ansible/roles/builder/defaults/main.yml
new file mode 100644
index 000000000..605761c04
--- /dev/null
+++ b/ansible/roles/builder/defaults/main.yml
@@ -0,0 +1 @@
+builder_delete_syslog: false
\ No newline at end of file
diff --git a/ansible/roles/builder/tasks/checks.yml b/ansible/roles/builder/tasks/checks.yml
new file mode 100644
index 000000000..4452c384c
--- /dev/null
+++ b/ansible/roles/builder/tasks/checks.yml
@@ -0,0 +1,29 @@
+- name: Check whether OFED is installed
+  command: ofed_info
+  changed_when: false
+  failed_when:
+    - _ofed_info.rc > 0
+    - "'No such file or directory' not in _ofed_info.msg"
+  register: _ofed_info
+
+- name: Get package facts
+  package_facts:
+
+- name: Check e.g. libfabric package hasn't downgraded OFED-installed packages
+  assert:
+    that: "'mlnx' in ansible_facts.packages[item].0.version"
+    fail_msg: "OFED is installed but package {{ item }} has a non-OFED version: {{ ansible_facts.packages[item].0.version }}"
+  when: "'MLNX_OFED_LINUX-' in _ofed_info.stdout"
+  loop: "{{ builder_ofed_check_packages }}"
+  vars:
+    builder_ofed_check_packages:
+      - ibacm
+      - infiniband-diags
+      - libibumad
+      - libibverbs
+      - libibverbs-utils
+      - librdmacm
+      - librdmacm-utils
+      - rdma-core-devel
+      - rdma-core # didn't actually see this one get downgraded
+  
diff --git a/ansible/roles/builder/tasks/finalise.yml b/ansible/roles/builder/tasks/finalise.yml
new file mode 100644
index 000000000..5f46f1161
--- /dev/null
+++ b/ansible/roles/builder/tasks/finalise.yml
@@ -0,0 +1,75 @@
+# Finalise a Packer build VM
+
+- meta: flush_handlers
+
+- name: Remove dnf caches
+  command: dnf clean all
+
+# If image build happens on a Neutron subnet with property dns_namservers defined, then cloud-init
+# disables NetworkManager's control of /etc/resolv.conf and appends nameservers itself.
+# We don't want network configuration during instance boot to depend on the configuration
+# of the network the builder was on, so we reset these aspects.
+- name: Delete /etc/resolv.conf
+  file:
+    path: /etc/resolv.conf
+    state: absent
+  when: "'resolv_conf' not in group_names" # if its been overriden, deleting it is the wrong thing to do
+
+- name: Reenable NetworkManager control of resolv.conf
+  # NB: This *doesn't* delete the 90-dns-none.conf file created by the resolv_conf role
+  # as if nameservers are explicitly being set by that role we don't want to allow NM
+  # to override it again.
+  file:
+    path: /etc/NetworkManager/conf.d/99-cloud-init.conf
+    state: absent
+
+- name: Get remote environment for ansible_user
+  setup:
+    gather_subset: env
+  become: no
+
+- name: Delete any injected ssh config for ansible_user
+  file:
+    path: "{{ ansible_env.HOME }}/.ssh/"
+    state: absent
+
+- name: Run cloud-init cleanup
+  command: cloud-init clean --logs --seed
+
+- name: Cleanup /tmp
+  command : rm -rf /tmp/*
+
+- name: Get package facts
+  package_facts:
+
+- name: Ensure image summary directory exists
+  file:
+    path: /var/lib/image/
+    state: directory
+    owner: root
+    group: root
+    mode: u=rwX,go=rX
+
+- name: Write image summary
+  copy:
+    content: "{{ image_info | to_nice_json }}"
+    dest: /var/lib/image/image.json
+  vars:
+    image_info:
+      branch: "{{ lookup('pipe', 'git rev-parse --abbrev-ref HEAD') }}"
+      build: "{{  ansible_nodename | split('.') | first }}" # hostname is image name, which contains build info
+      os: "{{ ansible_distribution }} {{ ansible_distribution_version }}"
+      kernel: "{{ ansible_kernel }}"
+      ofed: "{{ ansible_facts.packages['mlnx-ofa_kernel'].0.version | default('-') }}"
+      cuda:  "{{ ansible_facts.packages['cuda'].0.version | default('-') }}"
+      slurm-ohpc: "{{ ansible_facts.packages['slurm-ohpc'].0.version | default('-') }}"
+      ondemand: "{{ ansible_facts.packages['ondemand'].0.version | default('-') }}"
+
+- name: Clear system logs
+  file:
+    path: /var/log/messages
+    state: absent
+  when: "{{ builder_delete_syslog | bool }}"
+
+- name: Shutdown Packer VM
+  community.general.shutdown:
diff --git a/ansible/roles/ofed/defaults/main.yml b/ansible/roles/ofed/defaults/main.yml
index 0d040b55e..46902ded9 100644
--- a/ansible/roles/ofed/defaults/main.yml
+++ b/ansible/roles/ofed/defaults/main.yml
@@ -1,4 +1,4 @@
-ofed_version: '23.10-3.2.2.0' # LTS
+ofed_version: '24.07-0.6.1.0'
 ofed_download_url: https://content.mellanox.com/ofed/MLNX_OFED-{{ ofed_version }}/MLNX_OFED_LINUX-{{ ofed_version }}-{{ ofed_distro }}{{ ofed_distro_version }}-{{ ofed_arch }}.tgz
 ofed_distro: rhel # NB: not expected to work on other distros due to installation differences
 ofed_distro_version: "{{ ansible_distribution_version }}" # e.g. '8.9'
diff --git a/environments/.stackhpc/LEAFCLOUD.pkrvars.hcl b/environments/.stackhpc/LEAFCLOUD.pkrvars.hcl
index 5adf4199c..06bc27ebf 100644
--- a/environments/.stackhpc/LEAFCLOUD.pkrvars.hcl
+++ b/environments/.stackhpc/LEAFCLOUD.pkrvars.hcl
@@ -5,3 +5,4 @@ ssh_keypair_name = "slurm-app-ci"
 ssh_private_key_file = "~/.ssh/id_rsa"
 security_groups = ["default", "SSH"]
 floating_ip_network = "external"
+image_name_suffix = "-ofed24"
diff --git a/environments/.stackhpc/terraform/cluster_image.auto.tfvars.json b/environments/.stackhpc/terraform/cluster_image.auto.tfvars.json
index 9f396e964..9e5b2fdfb 100644
--- a/environments/.stackhpc/terraform/cluster_image.auto.tfvars.json
+++ b/environments/.stackhpc/terraform/cluster_image.auto.tfvars.json
@@ -1,7 +1,7 @@
 {
     "cluster_image": {
-        "RL8": "openhpc-RL8-241024-1439-177083b1",
-        "RL9": "openhpc-RL9-241024-1438-177083b1",
-        "RL9-cuda": "openhpc-cuda-RL9-241024-1628-177083b1"
+        "RL8": "openhpc-RL8-241101-1318-986306fe-ofed24",
+        "RL9": "openhpc-RL9-241101-1318-986306fe-ofed24",
+        "RL9-cuda": "openhpc-cuda-RL9-241101-1319-986306fe-ofed24"
     }
 }
\ No newline at end of file
diff --git a/packer/openstack.pkr.hcl b/packer/openstack.pkr.hcl
index fae0bf7b2..d3a0e24e0 100644
--- a/packer/openstack.pkr.hcl
+++ b/packer/openstack.pkr.hcl
@@ -23,6 +23,7 @@ data "git-commit" "cwd-head" { }
 locals {
     git_commit = data.git-commit.cwd-head.hash
     timestamp = formatdate("YYMMDD-hhmm", timestamp())
+    image_version = var.image_version == "auto" ? "${local.timestamp}-${substr(local.git_commit, 0, 8)}" : var.image_version
 }
 
 # Path pointing to root of repository - automatically set by environment variable PKR_VAR_repo_root
@@ -39,12 +40,6 @@ variable "networks" {
   type = list(string)
 }
 
-variable "os_version" {
-  type = string
-  description = "'RL8' or 'RL9' with default source_image_* mappings"
-  default = "RL9"
-}
-
 # Must supply either source_image_name or source_image_id
 variable "source_image_name" {
   type = string
@@ -123,19 +118,13 @@ variable "volume_type" {
 }
 
 variable "volume_size" {
-  type = map(number)
-  default = {
-    # fat image builds, GB:
-    rocky-latest = 15
-    rocky-latest-cuda = 30
-    openhpc = 15
-    openhpc-cuda = 30
-  }
+  type = number
+  default = 15 # same as default non-CUDA build
 }
 
-variable "extra_build_volume_size" {
+variable "volume_size_cuda" {
   type = number
-  default = 15 # same as default non-CUDA build
+  default = 30
 }
 
 variable "image_disk_format" {
@@ -148,27 +137,34 @@ variable "metadata" {
   default = {}
 }
 
-variable "groups" {
-  type = map(list(string))
-  description = "Additional inventory groups (other than 'builder') to add build VM to, keyed by source name"
-  default = {
-    # fat image builds:
-    rocky-latest = ["update", "ofed"]
-    rocky-latest-cuda = ["update", "ofed", "cuda"]
-    openhpc = ["control", "compute", "login"]
-    openhpc-cuda = ["control", "compute", "login"]
-  }
+variable "inventory_groups" {
+  type = string
+  description = "comma-separated list of inventory groups, in addition to 'builder'"
+  default = ""
 }
 
-variable "extra_build_groups" {
-  type = list(string)
-  default = []
+# variable "groups" {
+#   type = map(list(string))
+#   description = "Additional inventory groups (other than 'builder') to add build VM to, keyed by source name"
+#   default = {
+    # fat image builds:
+    # rocky-latest = ["update", "ofed"]
+    # rocky-latest-cuda = ["update", "ofed", "cuda"]
+    # openhpc = ["control", "compute", "login"]
+    # openhpc-cuda = ["control", "compute", "login"]
+#   }
+# }
+
+variable "image_name" {
+  type = string
+  description = "Built image name."
+  default = "openhpc"
 }
 
-variable "extra_build_image_name" {
+variable "image_version" {
   type = string
-  description = "Infix for 'extra' build image name"
-  default = "extra"
+  description = "Suffix for built image names. Default special value 'auto' uses a timestamp+git commit"
+  default = "auto"
 }
 
 source "openstack" "openhpc" {
@@ -176,7 +172,7 @@ source "openstack" "openhpc" {
   flavor = var.flavor
   use_blockstorage_volume = var.use_blockstorage_volume
   volume_type = var.volume_type
-  volume_size = lookup(var.volume_size, source.name, var.extra_build_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
@@ -204,39 +200,14 @@ source "openstack" "openhpc" {
 
 build {
 
-  # latest nightly image:
   source "source.openstack.openhpc" {
     name = "rocky-latest"
-    image_name = "${source.name}-${var.os_version}"
-  }
-
-  # latest nightly cuda image:
-  source "source.openstack.openhpc" {
-    name = "rocky-latest-cuda"
-    image_name = "${source.name}-${var.os_version}"
-  }
-
-  # OFED fat image:
-  source "source.openstack.openhpc" {
-    name = "openhpc"
-    image_name = "${source.name}-${var.os_version}-${local.timestamp}-${substr(local.git_commit, 0, 8)}"
-  }
-
-  # CUDA fat image:
-  source "source.openstack.openhpc" {
-    name = "openhpc-cuda"
-    image_name = "${source.name}-${var.os_version}-${local.timestamp}-${substr(local.git_commit, 0, 8)}"
-  }
-
-  # Extended site-specific image, built on fat image:
-  source "source.openstack.openhpc" {
-    name = "openhpc-extra"
-    image_name = "openhpc-${var.extra_build_image_name}-${var.os_version}-${local.timestamp}-${substr(local.git_commit, 0, 8)}"
+    image_name = replace(join("-", [var.image_name, local.image_version]), "/", "-")
   }
 
   provisioner "ansible" {
     playbook_file = "${var.repo_root}/ansible/fatimage.yml"
-    groups = concat(["builder"], lookup(var.groups, source.name, var.extra_build_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 = [