Exercise 02 — Preparing the Nodes

Ansible for Proxmox VE · Module 02

Author

credativ GmbH

~15 min · in ~/ansible-proxmox · after exercise 01

Objective: bring three freshly installed nodes to the state a cluster needs, and prove that running it a second time changes nothing.

Where to look

Everything here was on the slides; the handout for this module is the reference. Handlers · apt · deb822_repository · file · Proxmox package repositories

1 — Fill in the playbook

playbooks/10-node-prep.yml is a skeleton: the task names, the order and the handler are already there, and every body is an ansible.builtin.debug with a TODO. Replace the four that say TODO:

Task	Module
Update apt cache (the handler)	`apt`, `update_cache: true`
Disable the enterprise repositories	`file`, `state: absent`, over a loop
Enable the no-subscription repository	`deb822_repository`
Install the admin tools	`apt`

Uncomment the two notify: lines while you are there, and look the modules up rather than guessing:

ansible-doc ansible.builtin.deb822_repository    # uris, suites, components, signed_by
ansible-doc -s ansible.builtin.apt               # every option as a snippet

suites should be the release the node reports, not the string trixie. The fact is ansible_distribution_release.

Done when: task 2 gets past all four without an error.

2 — See what it would do

ansible-playbook playbooks/10-node-prep.yml --check --diff

Done when: tasks report changed, nothing fails, and the diff shows you the repository file before it is written anywhere.

3 — Run it, then run it again

ansible-playbook playbooks/10-node-prep.yml
ansible-playbook playbooks/10-node-prep.yml

Done when:

# first run
pve01 : ok=8  changed=4  unreachable=0  failed=0
# second run
pve01 : ok=7  changed=0  unreachable=0  failed=0

changed=0 is the point of the exercise. One task fewer on the second run is worth a second of thought: which one, and why?

4 — Two tasks that do not change anything

The playbook ends with a resolution check and a time check. Neither configures anything. Read those two tasks and answer for yourself why changed_when: false is on one of them, and what --check would do without check_mode: false on the other.

Done when: you can say what would break if both lines were removed.

If you finish early

Add htop to pve_packages in inventory/group_vars/pve.yml and re-run. How many tasks report changed?
ansible pve01 -m ansible.builtin.command -a 'pvecm status' still fails. That is module 03.
Break it on purpose: ansible pve03 -m ansible.builtin.command -a 'hostname bogus', then re-run with --limit pve03. Which task notices, and which does not? Set the hostname back afterwards.

Solutions

Solutions are discussed live with the trainer.