jakman85andClaude Opus 5
78bf68493d
The hostPath mechanism was MEASURED NOT TO WORK. In the live Plex pod on
k3s-prod-2, 2026-10-01: the device node was VISIBLE in the container
(`crw-rw---- root video2 226,128 renderD128`) and could not be opened --
`uid 0 O_RDWR -> EPERM` and `uid 1000 O_RDWR -> EPERM`. EPERM from the DEVICE
CGROUP, not EACCES from file permissions, proven three ways: root on the HOST
opens the same device rc=0; the node is unified cgroup2fs; and the container's
runc config.json read `linux.resources.devices: [{allow: False, access: 'rwm'}]`
with `linux.devices: None` -- one deny-all rule, no allow entry for major 226.
A hostPath is a filesystem operation: it binds the device node in but adds no
cgroup allow rule, because Kubernetes cannot infer one from a volume.
The Intel GPU device plugin produces that allow rule
(`createDeviceSpecsFromDrmFiles` emits `DeviceSpec{..., Permissions: "rw"}`).
It shipped as #36 and is live: all three prod nodes advertise
`gpu.intel.com/i915: 1`, DaemonSet 3/3/3 (measured 2026-10-01).
ZERO ServiceDefinition field changes, which was the entire point of making the
field an enum of capability classes rather than a device path. `catalog/plex.yaml`'s
`hardware:` block comes through byte-identical; only its comment changes, because
it restated the old mechanism. Contract invariant 8 holds, now demonstrated rather
than claimed.
- catalog/render.py: `DRI_VOLUME_NAME`/`DRI_DEVICE_DIR` retired for
`QUICKSYNC_RESOURCE`; the hardware branch now sets
`resources.limits["gpu.intel.com/i915"] = 1` on the APP container only (never a
sidecar) and emits no volume, no mount, no securityContext, no nodeSelector.
`limits` not `requests` is mandatory: Kubernetes mirrors requests from limits,
and a requests-only extended resource is invalid. This is the only app-container
`resources` render path and is deliberately narrow -- no general CPU/memory
feature was invented.
- selftests: resources dict asserted EXACTLY; hostPath/mount asserted ABSENT; the
no-`hardware` negative extended to `resources`; the podSecurityContext
pass-through and the no-synthesised-securityContext assertions kept; one new
assertion that the limit never reaches the oauth2-proxy sidecar. Mutation-tested:
8/8 mutants caught (requests-instead-of-limits, emission dropped, hostPath
re-added, emitted unconditionally, supplementalGroups synthesised, wrong resource
name, quantity as a string, limit leaked onto the sidecar).
- apps/wave-0/plex.yaml: six hostPath lines removed, a three-line resources block
added. Only golden touched; keycloak/vm-demo unchanged.
THE REGRESSION, STATED RATHER THAN SOLD. Before: device missing ->
`DirectoryOrCreate` mounted an empty dir -> Plex ran and SILENTLY
software-transcoded (invisible, harmless to everything else). After: resource
unavailable (plugin broken, removed, or not yet reconciled) -> Plex is
UNSCHEDULABLE, and `apps-wave-0` is `wait: true` with `apps-wave-1` dependsOn it,
so that STALLS THE APP TIER. Unavoidable: an extended resource is a hard
scheduling constraint, and it is also the only thing that produces the cgroup
allow rule. There is no graceful-degradation variant. Plex's schedulability is now
coupled to the intel-gpu-plugin DaemonSet. Escape hatch, one field and no code
change: delete the `hardware:` block from catalog/plex.yaml and re-render.
Documented in the contract, the runbook (its own top-of-page section and a
"Plex will not schedule" procedure) and the handoff.
HARDWARE TRANSCODING IS STILL NOT OBSERVED WORKING. The decisive open() test
cannot be re-run until this merges and Flux reconciles, and the Plex-side
`HardwareAcceleratedCodecs` toggle is still unset. A green gate proves the
manifest renders.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Alert runbooks — home-network-k3s prod
This is the index page served at https://home.keithjackson.dev/runbooks/.
Every alert rule in this platform carries an annotation of the form
runbook_url: "https://${BASE_DOMAIN}/runbooks/<name>"
46 of them, over 35 names. Until this directory existed, that path returned HTTP 404 on the live cluster: every alert that reached a human handed them a dead link at the exact moment they needed help. These pages are what makes the link resolve.
How to run the commands in these runbooks
kubectl does not work on the operator workstation. The toolchain lives only in the pinned dev
container, and the host's k3s-oidc context hangs on a browser prompt once its token expires — that hang
is not the cluster being down.
infra/devcontainer/dev.sh run bash -c 'kubectl --context k3s-prod get nodes'
Always pass --context k3s-prod. dev.sh merges BOTH clusters into one kubeconfig and picks a
current-context per invocation, and that default has already changed once — k3s-dev until dev was
decommissioned on 2026-09-13, k3s-prod now. A command that names its context still means the same thing
next month; one that relies on the default does not, and the failure is silent. CLUSTER=prod infra/devcontainer/dev.sh run kubectl ... selects it explicitly, and every invocation prints a banner
naming the cluster — read it. Do not run two dev.sh invocations at once; they share one container.
Use fully-qualified resource names, always. Three CRDs on this cluster register the kind Backup —
longhorn.io/v1beta2, postgresql.cnpg.io/v1, velero.io/v1 — and the bare short name resolves to
Longhorn's, which holds zero objects. kubectl get backup -A therefore prints "No resources found" on
a cluster holding 6 Velero and 27 CNPG backups (verified on prod 2026-09-13). Acting on that false
negative is how a CLI quirk becomes real data loss. Write backups.velero.io,
backups.postgresql.cnpg.io, clusters.postgresql.cnpg.io, settings.longhorn.io,
volumes.longhorn.io, nodes.longhorn.io.
Merging a PR into main is the deploy; there is no other apply step. main is protected, so a
direct push is rejected — durable changes go through a branch, a PR, and a green gate.
Alerts you should not trust the silence of (measured 2026-09-13)
The Longhorn and cert-manager scrapes were ENABLED on 2026-09-13, so the Longhorn row below is no
longer inert — and re-keying the two robustness rules the same day fixed a SECOND inertness the
scrape had left in place (the metric is one-hot over a state label, not a 0–3 enum). Take the
Longhorn row as history; the rest of this table still holds, and Flux-controller and Hubble/Cilium
rule groups still evaluate against nothing and cannot fire:
| Missing scrape job | Inert alerts |
|---|---|
| Longhorn | LonghornVolumeDegraded, LonghornVolumeFaulted, LonghornDiskAllocationHigh, LonghornDiskUnschedulable |
| cert-manager | CertificateExpiringSoon, CertificateExpiryImminent, CertificateNotReady |
Flux (gotk_*) |
FluxReconciliationFailure, FluxResourceSuspended, ImageUpdateAutomationFailing, ImagePolicyStalled, UpdateHealthGateFailed |
Hubble (hubble_drop_total) |
HubbleDeniedFlowSpike |
etcd (kubeEtcd disabled for k3s, deliberately) |
no etcd fsync alerting exists at all |
Each affected runbook says so on its own page and gives the by-hand equivalent. See targets-down.
The runbooks
Nodes
node-down— a node's node-exporter is unscrapable; the node may be gone, or its kubelet may have stopped posting status while the host stays up (the 2026-09-07 shape).node-io— disk I/O pressure/starvation. The etcd WAL shares a partition with Longhorn replicas; this is the alert that would have called the 2026-09-07 outage and did not exist at the time.node-memory— memory pressure. Includes whySwapTotal == 0is not evidence swap is off.node-disk— a node filesystem filling up./datais the one that matters.node-cpu— CPU PSI and run-queue depth, and how to tell CPU contention from I/O contention.
Storage
longhorn-degraded— a volume has lost redundancy. Normal after any reboot, and the rebuild is the expensive part. Freeze/thaw commands here.longhorn-faulted— no usable replica. Data at risk; stop before anything destructive.longhorn-capacity— a node's Longhorn disk running out of room for replicas (allocation, not PVC fill; for PVC fill seepvc-capacity/monitoring-capacity).pvc-capacity— PVC filling up / almost full / predicted to fill. These rules work.monitoring-capacity— Prometheus or Loki running out of disk; don't let the monitor blind itself.
GitOps and updates
flux-reconcile— a Flux resource stuck at Ready=False. Which tier decides the blast radius.flux-suspended— reconciliation turned off and forgotten. Drift becomes silent.update-rollback— a HelmRelease failed its health gate and is rolling back.image-automation— the git write-back engine is failing (feature is disabled here).image-policy-stalled— an ImagePolicy/ImageRepository cannot resolve a tag.
Certificates
cert-issuance— ACME issuance failing. The DNS-01 self-check is the usual cause.cert-expiry— a certificate is expiring. Almost always a late symptom ofcert-issuance.
Networking
vpn-down— the egress VPN tunnel. Explains what the kill-switch actually does, and the silent egress-gateway staleness this alert cannot see — which now has its own alerts and page below.vpn-egress-stale— the tunnel is UP butegress-class=vpnpods have no egress: Cilium's cached ifindex outlived a reconnect. Also covers the watchdog for that rule going inert.denied-flows— policy-denied flow spike. The Cilium hairpin/identity regression class.
Backups and DR
backup-failure— a Velero backup failed. The R2 object-tagging incompatibility is documented here.backup-partial— a Velero backup completed with partial failures, and which skips are deliberate.backup-missed— no successful Velero backup in 24h.cnpg-archiving— WAL archiving stuck / no recoverability point. An availability incident, not just a backup one.cnpg-backup-missed— no recent CNPG base backup. Velero does not cover these databases.cnpg-wal-growth—pg_walnot being recycled. Never delete WAL by hand.cnpg-exporter— the CNPG SQL exporter erroring: a blind spot that looks exactly like health.cnpg-primary-spread— two or more CNPG primaries on one node. Blast radius, not an outage, and the rebalance costs ~9s of writes per database — one cluster at a time.
Identity
keycloak-down— the IdP is down. Blast radius, and the break-glass path that still works.keycloak-db— Keycloak's CloudNativePG database is unavailable.keycloak-client-secrets— the client/URL reconciler failing or silent. The 2026-09-06 lockout that every green signal missed.
Operator procedures (no alert links here)
plex-claim— claiming the Plex Media Server. Claimed 2026-09-29; the page now only applies after a/configwipe. The claim token is short-lived — read the countdown on plex.tv/claim — so it is a timed sequence, scripted asinfra/plex/claim-ship.sh: token →sops→ PR → gate → merge → forcedflux reconcile→ pod roll (~2m45s measured). Includes why a changed Secret does not restart anything, and why an expired token is harmless.plex-quicksync— hardware transcoding on the host iGPU. GitOps puts/dev/driin the pod (hardware.gpu: intel-quicksync); a human still has to tick Settings → Transcoder → "Use hardware acceleration when available", and no environment variable can do it (the image supports noPLEX_PREFERENCE*, verified). The page names the real preference key (HardwareAcceleratedCodecs, read out of the binary), says which widely-cited key does not exist, and is explicit that the only proof isTranscode (hw)on the Plex dashboard — Plex renders no ServiceMonitor, so no alert could ever fire. Also: the device-cgroup failure to expect first and its device-plugin fallback, and why a:latestpull can silently break it.oauth2-proxy-session— a gated UI loads but its saves quietly do nothing, and you are never re-prompted to log in. Tells the three stacked auth layers apart from the sidecar's own access log (the four lines that matter, including the upstream-that means the proxy answered a request the app never saw). Covers the cookie collision between per-app sidecars sharing the default_oauth2_proxyname on.home.keithjackson.dev— which deletes sessions belonging to apps in other namespaces and is only legible with two logs side by side — the 5-minute access-token session with no--cookie-refresh, and why an XHR answered with a 302 instead of a 401 loses a POST body silently.crafty-admin-credential— you signed into Keycloak and Crafty still asks for a password. Expected: Crafty 4 has no OIDC, so its own local login sits behind the oauth2-proxy gate as a second factor. The page tells the two layers apart from the sidecar log, and explains that the bootstrap password exists only on the PVC (default-creds.txt, generated once on first boot, never in git). Includes the argon2 reset for a lost password, why the 3-strikes lockout cannot fire behind the sidecar, and why deletingcrafty.sqliteto force a new password destroys every server definition.
Virtualisation
kubevirt-control-plane— VM lifecycle operations will fail; running VMs keep running.kubevirt-launch-failed— a VMI reached the Failed phase. The three k3s-specific launch traps.kubevirt-crashloop— a virt-launcher pod restarting repeatedly.cdi-import-stuck— a DataVolume import not progressing. Check node I/O before restarting it.
Editing a runbook
Each page is runbooks/<name>.md in the home-network-k3s-impl repo. Edit it, push to main, and Flux
re-renders the ConfigMap and rolls the two-replica server; kustomize's content hash on the generated
ConfigMap name is what triggers the roll.
Adding a new alert with a runbook_url requires the matching runbooks/<name>.md and its
<name>=<name>.md entry in runbooks/kustomization.yaml. Both are enforced by
conformance/tests/l0-static/alert-runbooks-resolvable, which runs unconditionally in the merge gate —
"the file exists in git" and "the URL resolves in the cluster" are different claims, and it checks both.
Every page must carry the four operator sections (What this means here, First commands, Likely
causes, most likely first, When to escalate or stop), mention dev.sh, and pass --context k3s-prod.
The check enforces that too, because a stub that makes the link resolve while helping nobody is worse than
the 404 it replaced — it looks fixed.
Why this route has no login
Deliberately public. The UIs that declare forward-auth (pihole, jackett, qbittorrent, radarr, sonarr)
really are closed: enforcement is per-pod, each one's HTTPRoute targeting its oauth2-proxy sidecar on
:4180 rather than the app port. If
these pages did too, keycloak-down would be unreadable exactly when Keycloak is down,
keycloak-db unreadable when its database is down, and keycloak-client-secrets unreadable during the
precise failure that broke all 12 OIDC clients on 2026-09-06 behind an entirely green cluster. An
operator who cannot log in is this route's primary reader. The content is operational procedure — metric
names, thresholds, kubectl invocations, topology — and no secrets. See
runbooks/serving/httproute.yaml for the full reasoning, including how forward-auth is actually
enforced here and the instruction to leave this route out of any Gateway-level ext-authz attachment
if one is ever introduced.
The running narrative of real incidents on this cluster is DECISIONS-LOG.md.