jakman85
a819c50ffe
roles/etcd_io_priority + playbooks/etcd-io-priority.yml, enabled for [k3s_prod]
only. Mitigation for the 2026-09-07 k3s-prod-1 outage: etcd's WAL fdatasync took
3.4-6.7 s (expects 1 s), the node went NotReady while the host stayed up, and
/proc/pressure/io full avg300 read 11.36 there against 0.75 (node 2, NVMe) and
1.29 (node 3).
WHAT IT DOES, on the SATA nodes only:
1. k3s-etcd-io-priority.service (oneshot, Before=k3s.service) switches the
shared device to BFQ and drops nr_requests 64 -> 32.
2. IOWeight=10000 drop-ins on system.slice AND k3s.service, which BFQ turns
into io.bfq.weight=1000 — a 10:1 share against the default-weighted
kubepods.slice where Longhorn's instance-managers live.
3. Reads all of it back out of the kernel and ASSERTS. If the scheduler did
not switch or the weight did not land, the play fails.
THE THREE OBVIOUS ANSWERS ARE INERT ON THESE NODES, ALL CHECKED LIVE, ALL
DELIBERATELY ABSENT:
* IOSchedulingClass=realtime on k3s.service. mq-deadline DOES honour the
priority class, so this looks right — but ioprio is inherited across fork
and kept across exec (block/blk-ioc.c __copy_io copies ioc->ioprio) and
CONTAINERD IS A CHILD OF THE K3S SERVER PROCESS. Verified on k3s-prod-1:
containerd pid 84553 has ppid 84333 = k3s-server, and
ionice -c2 -n0 -- sh -c 'ionice -p $$; sh -c "ionice -p \$\$"'
prints best-effort prio 0 at both levels. Realtime for k3s is realtime for
every container on the node, Longhorn included. No relative gain.
* IOSchedulingPriority (the level inside a class): mq-deadline buckets by
CLASS only, so BE-0 vs BE-4 is a no-op.
* io.latency, which would be the ideal scheduler-independent protection:
CONFIG_BLK_CGROUP_IOLATENCY is not built in Debian trixie's 7.1.8 kernel
(only IOCOST is) and no io.latency file exists under /sys/fs/cgroup.
AND ONE NON-OBVIOUS TRAP: bare IOWeight= is DECORATION here. systemd writes it
to io.weight (blk-iocost — compiled in but disabled, io.cost.qos is empty) and
io.bfq.weight (BFQ — not loaded). Neither reader exists on the stock nodes, so
the scheduler change and the weights have to be one role with one verification.
The value is 10000 rather than a "reasonable" 1000 for the same reason: systemd
rescales 1..10000 onto io.bfq.weight's 1..1000, so 1000 maps to ~101 against
BFQ's unweighted default of 100. The role asserts the result is >= 500.
k3s-prod-2 IS SKIPPED ON PURPOSE. The role discovers the device under
k3s_data_dir per node (verified: prod-1/3 -> /dev/sda5 -> sda, prod-2 ->
/dev/nvme0n1p5 -> nvme0n1) and writes NOTHING on NVMe rather than leaving inert
files behind — BFQ is a poor fit for NVMe and node 2 measured 0.75 IO PSI.
DEV IS UNTOUCHED. Master switch defaults false and is set true only in
group_vars/k3s_prod; dev has a dedicated etcd device (docs/plans/ssd-etcd-
isolation.md) and nothing to arbitrate. Verified with --list-hosts: no extra
vars -> the three dev hosts (where the role is a no-op); -e k3s_hosts=k3s_prod
-> the three prod hosts; --limit k3s-prod-3 -> one.
NOTHING IS RESTARTED. The oneshot writes two sysfs files; the weights go in
through daemon-reload. If daemon-reload turns out not to re-realize a running
k3s.service's cgroup, the verification FAILS and names the rolling restart as
the fix rather than quietly leaving the weight unapplied.
WHAT IT CANNOT DO, stated in the role README and worth repeating: it does not
separate the two tenants. Both still write one ext4 filesystem, and no cgroup
control arbitrates the shared jbd2 journal that etcd's fdatasync waits on. It is
also UNPROVEN on this hardware — it fails loudly if the settings do not land, it
cannot tell you they helped. Apply to k3s-prod-3 first and watch
NodeIOPressureHigh. Replacing the C400 / giving etcd its own device remains the
real fix and the operator's (PROD-PROVISIONING.md §2 exit condition).
Syntax-checked, and the fact-derivation and assert expressions were exercised
offline against all three node shapes plus negative controls (a node still on
mq-deadline fails the gate; IOWeight=1000 -> 101 fails the floor).
Co-Authored-By: Claude Opus 5 <[email protected]>
(cherry picked from commit de8c1f832724c011b03466842e18296de07a6776)
home-network-k3s-impl
Implementation of the home k3s + Longhorn platform. This repo holds the reconciled artifacts
(Flux config, Kustomize overlays, KubeVirt/Helm manifests, ServiceDefinitions, Kyverno policies,
Chainsaw conformance tests, CI). It is driven by — and subordinate to — the read-only
specification at ../home-network-k3s.
Rules (from the spec — non-negotiable)
- The spec is read-only. Never modify anything under
../home-network-k3s. Implement against it; escalate spec problems, don't edit them (specAGENTS.md§11, R-TEST-06). - Done = a green, reproducible, requirement-tagged conformance test — never "merged," never a
manual demo (spec
docs/14,agents/definition-of-done.md). - No work on
main. Every change is a feature branch merged intomain(specCONTRIBUTING.md). - No plaintext secrets — SOPS-encrypted only (spec
docs/07). - Phase discipline — only build what the active roadmap phase authorizes (spec
roadmap/phases.md).
Layout
infra/ node provisioning: OpenTofu (Proxmox VE) + cloud-init + Ansible, and the
pinned dev container that carries the whole toolchain
bootstrap/ one-time cluster bootstrap: Flux install, SOPS/age key, host Gitea
platform/ platform CONTROLLERS (Flux HelmReleases / operator bases): kyverno, cilium,
longhorn, external-snapshotter, cert-manager, externaldns, gateway, coredns,
vpn-egress, monitoring, cnpg, keycloak, oauth2-proxy, kubevirt
platform-config/ platform CONFIGS — the custom resources of the CRDs installed above
(ClusterIssuers, Gateway, Kyverno policies, KubeVirt/CDI CRs, Keycloak CRs).
Split out because CRs and the CRDs they use cannot apply in one pass.
apps/ application tier, reconciled as dependency-ordered WAVES:
wave-0/ wave-1/ wave-2/ rendered container apps (see DESIGN-waves.md)
vms/ KubeVirt VirtualMachines (non-gating tier)
catalog/ ServiceDefinition entries (the onboarding surface) + render.py
schemas/ ServiceDefinition JSON Schema + renderer contract
clusters/ Flux entrypoints + dev/ and prod/ overlays
conformance/ Chainsaw behavior/conformance suite + harness + coverage report
ci/ the gate as scripts (lint · schema · Kyverno L0 · L1 render · decision)
.gitea/ Gitea Actions CI running that gate on an in-cluster runner
Status
Roadmap phases 0–6 are delivered and deployed on the dev cluster; Phase 7 (prod) is not
open — clusters/prod is a design-only overlay.
| Phase | Delivered |
|---|---|
| 0 Foundations | ServiceDefinition schema + renderer, Kyverno L0 gate, conformance harness, CI |
| 1 Cluster bring-up | 3-node k3s HA on Proxmox VE (192.168.1.50/.51/.52), Cilium, Flux, SOPS |
| 2 Platform core | Cilium · Longhorn · cert-manager (LE-prod wildcard) · ExternalDNS · Gateway API · split-horizon CoreDNS |
| 3 Egress / VPN | ADR-0015 node-level OpenVPN split-tunnel + Cilium egress-gateway steering + host kill-switch |
| 4 Observability | kube-prometheus-stack · Loki · Alloy · Alertmanager. Velero still blocked on OQ-BKP; image-automation authored but disabled |
| 5 IaaS | KubeVirt + CDI on real nested KVM; live-migratable RWX VM storage. The UniFi VM runs, but UniFi OS Server is not yet installed in the guest |
| 6 Identity + CI | Keycloak (Operator + CNPG) · oauth2-proxy forward-auth · Grafana OIDC · kubectl OIDC SSO with group→RBAC · in-cluster Gitea Actions merge gate |
Conformance: 36 / 51 requirements covered (70.6%), 15 gaps, 1 safety-critical gap
(R-STATE-02, Longhorn node-loss). Regenerate with ./conformance/run.sh --coverage-only;
the full report is conformance/_artifacts/coverage/coverage.md.
The running narrative — decisions, root causes, incidents, follow-ups — is
DECISIONS-LOG.md. It, not this table, is the authoritative record.
Working on this repo
Everything the gate needs is baked into the pinned dev container — do not install the toolchain on the host:
infra/devcontainer/dev.sh build # once
infra/devcontainer/dev.sh run make -C ci gate # the same gate CI runs
infra/devcontainer/dev.sh # interactive shell (sops, flux, kubectl, tofu, ansible)
The container mounts the repo at /work, your age keyring, and the sibling spec repo read-only
so the spec-immutability check can actually run. See
infra/devcontainer/README.md.
A green run prints MERGE GATE: PASS. The L2/L3 conformance layers stay SKIPPED unless
CLUSTER_AVAILABLE=true — the static gate never pretends to have run them.