jakman85 efc6db6c1f feat(obs): alert on I/O pressure — the metric that missed the prod-1 outage
On 2026-09-07 06:05:21Z k3s-prod-1 went NotReady ("Kubelet stopped posting node
status") with the host up, pingable and SSH-able. The cause was disk I/O
starvation of the embedded etcd, from its own journal:

  slow fdatasync               took=3.56s / 6.71s / 4.95s / 3.40s (expects 1s)
  apply request took too long  took=8.30s                         (expects 100ms)
  etcdserver: too many requests

/proc/pressure/io FULL avg300 read 11.36 on k3s-prod-1 against 0.75 on
k3s-prod-2 (NVMe) and 1.29 on k3s-prod-3 — all three nodes put /data/k3s
(etcd's WAL) and /data/longhorn (every replica) on ONE partition, and node 1's
is a 2011 consumer SATA SSD with 61,440 reallocated sectors.

The stack alerted on CPU-PSI and memory and had NO I/O alert at all, so the
first signal the operator got was a node already out of the cluster. Adds:

  NodeIOPressureHigh      full IO PSI > 5%  for 10m  warning
  NodeIOPressureCritical  full IO PSI > 10% for 5m   critical

Thresholds are measured, not guessed: rate() is a 0-1 fraction, so the outage's
11.36% is 0.1136 and the healthy steady state on the same node is ~0.01.
Verified live that node-exporter already exports
node_pressure_io_{stalled,waiting}_seconds_total for all three prod nodes, so
these rules fire on arrival — no new exporter, no scrape change. (etcd's own
fsync histograms are NOT available: kube-prometheus-stack's kubeEtcd scrape job
is deliberately disabled for k3s, so PSI is the signal we actually have.)

PSI *full* (every runnable task blocked on disk), not *some*: `some` is noisy on
a storage node and did not separate the failing node from its peers.

Dashboard gains the matching I/O row and is retitled accordingly. Not scoped to
prod — dev shares this file and its k3s VMs are HDD-backed, where the same alert
is if anything more likely to earn its keep.

Co-Authored-By: Claude Opus 5 <[email protected]>
(cherry picked from commit cb28fc80e7e2085d2539530d55f90fc92e3b1bba)
2026-09-07 02:46:26 -05:00

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 (spec AGENTS.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 into main (spec CONTRIBUTING.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.

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