Development notes

Host/instance/resource/inventory names

Updated 19th Dec 2025

There's a very implicit requirement in various places that inventory_hostname is a resolvable name. E.g. here

The logic is:

• FQHN is templated from TF cluster_nodename_template which is overrideable for node groups (e.g. site/tofu/control.tf#L7)
• instance names are always the first dotted portion of the FQHN (e.g. environments/site/tofu/control.tf#L48)
• host name is always set as FQHN via cloud-init (e.g. environments/site/tofu/control.tf#L97)
• the for_each key for the instance in the TF resource is either just "control" or an element of the nodegroups nodes parameter (e.g. environments/site/tofu/node_group/nodes.tf#L158
• inventory_hostname is always the instance name (e.g. environments/site/tofu/inventory.tpl#L10)
• By default, /etc/hosts is written with the FQHN or inventory_hostname (fallback is only for older appliances which didn't have FQHN - we could remove this if everyone is on later TF configs)

so:

• inventory_hostname => first dotted portion of FQHN => resolvable via /etc/hosts

Interfaces

Moved to here

Running install tasks only

Which roles can we ONLY run the install tasks from, to build a cluster-independent(*)/no-config image?

In-appliance roles:

• basic_users: n/a
• block_devices: n/a
• filebeat: n/a but downloads Docker container at service start)
• grafana-dashboards: Downloads grafana dashboards
• grafana-datasources: n/a
• hpctests: n/a but reqd. packages are installed as part of openhpc_default_packages.
• opendistro: n/a but downloads Docker container at service start.
• openondemand:
  • main.yml unnamed task does rpm installs using osc.ood:install-rpm.yml
  • main.yml unnamed task does rpm installs using pam_auth.yml.
  • main.yml [unnamed task] does git downloads using osc.ood:install-apps.yml
  • jupyter_compute.yml: Does package installs
  • vnc_compute.yml: Does package installs
• passwords: n/a
• podman: prereqs.yml Does package installs

Out of appliance roles:

• stackhpc.nfs: [main.yml(https://github.com/stackhpc/ansible-role-cluster-nfs/blob/master/tasks/main.yml) installs packages.
• stackhpc.openhpc: Required and openhpc_packages (see above) installed in install.yml but requires openhpc_slurm_service fact set from main.yml.
• cloudalchemy.node_exporter:
  • install.yml does binary download from github but also propagation. Could pre-download it and use node_exporter_binary_local_dir but install.yml still needs running as it does user creation too.
  • selinux.yml also does package installations
• cloudalchemy.blackbox-exporter: Currently unused.
• cloudalchemy.prometheus: install.yml. Same comments as for cloudalchemy.node_exporter above.
• cloudalchemy.alertmanager: Currently unused.
• cloudalchemy.grafana: install.yml does package updates.
• geerlingguy.mysql: setup-RedHat.yml does package updates BUT needs variables.yml running to load appropriate variables.
• jriguera.configdrive: Unused, should be deleted.
• osc.ood: See openondemand above.

• It's not really cluster-independent as which features are turned on where may vary.