Dominik Schön
5cf6a573f1
New patterns: - PAT-008: Ansible default_ipv6 fact missing on fresh VMs - PAT-009: Stale NBD devices after RBD volume swap Updated: - index.md: added PAT-008, PAT-009 - log.md: retrospective entry with 4 solution docs + 2 patterns - Solution docs dispatched to ~/docs/solutions/
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1.9 KiB
pattern_id, title, category, severity, status, first_observed, last_updated, related_systems, related_solution_docs, related_skills
| pattern_id | title | category | severity | status | first_observed | last_updated | related_systems | related_solution_docs | related_skills | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| PAT-008 | Ansible default_ipv6 fact missing on fresh VMs → lablabs.rke2 role fails | tooling | medium | active | 2026-07-21 | 2026-08-30 |
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Ansible default_ipv6 fact missing on fresh VMs → lablabs.rke2 role fails
Symptom
The lablabs.rke2 Ansible role fails on freshly provisioned VMs with a Jinja2 error:
ansible_facts['default_ipv6']['address']
The default_ipv6 fact doesn't exist on VMs without IPv6 configured, causing the
meta/argument_specs.yml validation to crash.
Root Cause
The lablabs.rke2 role's meta/argument_specs.yml references
ansible_facts['default_ipv6']['address'] with a hardcoded default. On fresh VMs
without IPv6, ansible_facts['default_ipv6'] is undefined → Jinja2 raises
UndefinedError.
A pre_task setting default_ipv6 via combine() doesn't help because the
argument_specs validation runs BEFORE pre_tasks — it re-collects facts and
overwrites the pre_task fix.
Mitigation
Patch meta/argument_specs.yml directly in the role:
# Replace:
default: "{{ ansible_facts['default_ipv6']['address'] }}"
# With:
default: "{{ ansible_facts.default_ipv6.address | default(None) }}"
Or: enable IPv6 on the target VMs (faster workaround, no role patching needed).
Prevention
- Pin Ansible roles and patch argument_specs when they assume facts that may not exist
- Test roles on fresh VMs without IPv6 before production use
- Consider forking the role with the fix upstream
Evidence
- Observed during GPU worker provisioning (worker-04/05, Jul 2026)
- Solution doc:
docs/solutions/bug-fixes/2026-07-21-ansible-rke2-default-ipv6-bug.md - Session: @session:default/20260721_115501_78b25032