Michal 2048515578 labsim etcd harness: etcd timer tuning for the constrained host + run notes ...

First run of the 3-server harness: the config path works (VMs boot, config.yaml
rendered by the production generator, k3s installs, etcd forms), but three full
control-plane servers starved etcd of CPU on a labsim host running 18 VMs (load
8+). etcd lost leader continuously -> "storage is (re)initializing" -> k3s stuck
activating -> datastore reset. Not a harness bug; host capacity + etcd's latency
intolerance.

Fixes for a clean next run:
- LAB-ONLY etcd tuning (heartbeat-interval=500, election-timeout=5000) in the
  install exec, clearly marked as not-production and not affecting what the
  conversion test exercises -- the standard remedy for etcd under nested-virt.
- Shut the other labsim k8s/dualstack VMs before `up` (done at teardown).

Also fixed a real sim drift found en route: the sim MASTER router lacked the NAT
masquerade rules the backup had, so LAN had no internet whenever .253 was master.
Added masquerade for 172.31.0.0/16 out bond0.53 + pppoe0.

Full write-up: labsim/dualstack-evidence/etcd-harness-2026-09-07.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH

2026-09-08 00:32:11 +01:00

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