HOWTOs

Use a hook from a parent environment

Hooks from parent environments don't get run by default as site.yml relies on APPLIANCES_ENVIRONMENT_ROOT to find them. But you can explicitly run them using :

# environments/child/hooks/pre/yml
- name: Import parent hook
  vars:
    appliances_environment_root: "{{ lookup('env', 'APPLIANCES_ENVIRONMENT_ROOT') }}"
  import_playbook: "{{ appliances_environment_root }}/../parent/hooks/pre.yml"

where child and parent are the environment names.

Create a cluster with a combined compute/control/login node

• Create a group control containing just the first compute node, and add that group into hpctests, e.g. in environments/<myenv>/inventory/groups:

  [control]
  combined-compute-0
  
  [hpctests:children]
  control

• Do NOT create a group login (that is for login-only nodes)

• Create a post-hook like this:

  - hosts: control
    become: true
    tasks:
      - name: Prevent ansible_user's processes being killed on compute nodes at job completion
        replace:
          path: /etc/slurm/slurm.epilog.clean
          regexp: 'if \[ \$SLURM_UID -lt 100 \] ; then'
          replace: "if [[ $SLURM_UID -lt 100 || $SLURM_JOB_USER -eq {{ ansible_user }} ]] ; then"

Rerun slurm configuration fast(ish)

You can rerun the slurm setup (e.g. for partition/node changes, slurm template debugging) faster using:

$ ansible-playbook ansible/slurm.yml --tags openhpc --skip-tags install

Run CI and merge a PR from a fork

Github won't (by default) inject secrets into forked repos, so the OpenStack-based CI won't run as the runner won't have access to the credentials needed to access our OpenStack. In addition, the repo is configured to require approval on workflows from forked repos (which should therefore be denied, because they can't do anything useful).

The proposed approach is therefore as follows:

• Review the PR for correctness.
• Review the PR for safety, i.e. no changes which could leak the repository secrets, provide access to or leak information about our infrastructure
• Get changes made until happy.
• Create a new branch and change the merge target for that PR to that new branch.
• Merge the PR into the new branch - this will run CI.
• Make tweaks as necessary.
• Go through normal (internal) review to merge new branch into main.
• Merge new branch into main.