jakman85andClaude Opus 5
44983095e1
Every platform-health alert rule carries `runbook_url: "https://${BASE_DOMAIN}/runbooks/<name>"` — 42 annotations over 34 distinct names, across platform/monitoring/alerts.yaml, platform/monitoring/pvc-capacity-alerts.yaml, platform/cnpg/alerts.yaml and platform/kubevirt/alerts.yaml. There was no runbooks/ directory and no HTTPRoute serving that path: an in-cluster probe of https://home.keithjackson.dev/runbooks/node-down returned HTTP 404. Every alert that reached a human handed them a dead link at the exact moment the documentation is read, and the annotation made it look solved — the same green-surface-over-absent-mechanism class as the import Job that reported success while storing placeholder secrets. No alerts.yaml is touched and no runbook_url value changes. The existing URL scheme is made to resolve instead. WHAT LANDS - runbooks/<34>.md — one per name, each grounded in this cluster's real topology and, where one exists, its real incident history: the 2026-09-07 k3s-prod-1 etcd I/O starvation (measured PSI 11.36 vs 0.75/1.29, the exact journal lines, the four mechanisms proven inert), the Longhorn reboot tax and the freeze/thaw of concurrent-replica-rebuild-per-node-limit, Cilium's once-resolved egress interface cache (Ifindex 3 against a live 1780) and the absence of OSS failover, the CNPG 38-hour ContinuousArchiving=False with its measured 6.8 MiB/h disk-full clock and the 2026-09-12 aggregation-scope fix, the 2026-09-06 Keycloak lockout in which all 12 clients held literal placeholder secrets behind an entirely green cluster, the Velero R2 x-amz-tagging NotImplemented incompatibility and its v1.14.3-rc.2 pin, and swap re-enabling itself across reboots via systemd-gpt-auto-generator. Each page states what the alert means HERE, the first diagnostic commands, likely causes ordered by probability with a remediation each, and when to escalate or stop. - Every page uses FULLY-QUALIFIED resource names and says why: three CRDs register the kind `Backup` here, the bare short name resolves to Longhorn's (zero objects), so `kubectl get backup -A` prints "No resources found" on a cluster holding 6 Velero and 27 CNPG backups. Acting on that false negative is how a CLI quirk becomes data loss. - Every page states that kubectl only works via `infra/devcontainer/dev.sh run bash -c '...'` with an explicit `--context k3s-prod`, because dev.sh defaults its current-context to k3s-dev. - Pages also record which alert groups are INERT today (measured 2026-09-13: no Longhorn, cert-manager, Flux-controller or Hubble scrape job exists, so 13 rules evaluate against nothing) so nobody reads their silence as health. SERVING — runbooks/serving/ plus clusters/base/runbooks.yaml A two-replica nginx-unprivileged serving a ConfigMap generated from runbooks/*.md, at the apex `/runbooks` prefix, in its own non-gating post-platform Flux tier (dependsOn platform-config, wait:false) — the platform/homepage pattern, file for file. - The service catalog cannot express this route: ingressRoutes[].host is pattern-bound to a single DNS label plus the apex, so the bare apex is unrepresentable, and there is no path field. - Rejected: redirecting to the Gitea web UI. A runbook is read when the platform is broken, and Gitea is an app-tier workload whose own dependencies several of these runbooks document; Gateway API's RequestRedirect also has no "append .md" modifier, so it would need 34 hand-maintained ReplaceFullPath rules. - configMapGenerator maps each file to an EXTENSIONLESS key (node-down=node-down.md), so /runbooks/node-down is a plain static lookup with no rewrite rule. Served as text/plain: the namespace has DNS-only egress, so a CDN markdown renderer could not load anyway. - The tier declares NO postBuild.substituteFrom, deliberately: envsubst would run over the prose and silently empty every ${...} shell example (it fails open — the 2026-09-01 emptied Cilium k8sServiceHost). The HTTPRoute omits `hostnames:` and inherits the https-apex listener's, so nothing needs substituting. AUTH — PUBLIC, deliberately auth-mode=none. Gating these pages behind oauth2-proxy/Keycloak would make runbooks/keycloak-down unreadable when Keycloak is down and runbooks/keycloak-client-secrets unreadable during the exact 2026-09-06 failure mode. An operator who cannot log in is this route's primary reader. Content is operational procedure only, no secrets. The rationale is recorded in an annotation on the HTTPRoute so the route is left OUT of the Gateway ext-authz attachment when forward-auth enforcement lands. PROVEN — in-cluster probe through the Gateway on prod /runbooks/node-down HTTP 200 8613 bytes text/plain; charset=utf-8 /runbooks/keycloak-down HTTP 200 9378 bytes text/plain; charset=utf-8 /runbooks/cnpg-archiving HTTP 200 11729 bytes text/plain; charset=utf-8 /runbooks/longhorn-faulted HTTP 200 9135 bytes text/plain; charset=utf-8 /runbooks/vpn-down HTTP 200 11092 bytes text/plain; charset=utf-8 /runbooks/backup-failure HTTP 200 9604 bytes text/plain; charset=utf-8 HTTPRoute Accepted by io.cilium/gateway-controller on sectionName https-apex; the `/runbooks` prefix wins over homepage's apex `/` by Gateway API longest-path precedence. GUARD — conformance/tests/l0-static/alert-runbooks-resolvable (R-OBS-04) 363 offline assertions. It checks BOTH halves, because the regression is silent in both directions: an alert with a new runbook_url and no runbook links to a 404, AND a runbook committed without its configMapGenerator entry is in git, reviewed, merged, and still 404s in the cluster. Also asserts a quality floor so a stub cannot make the link look fixed, and that route/listener/nginx prefix agree with the annotations. Proven to fail, then reverted: a bogus runbook_url (2 FAIL), a runbook removed from the generator (1 FAIL), and a 31-byte stub (7 FAIL). Co-Authored-By: Claude Opus 5 <[email protected]>
128 lines
7.2 KiB
Markdown
128 lines
7.2 KiB
Markdown
# node-disk — A node filesystem is filling up
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**Alert:** `NodeDiskFillingUp` (warning, 15m)
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**File:** `platform/monitoring/alerts.yaml`, group `platform-health.nodes`
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**Expression:** `node_filesystem_avail_bytes{fstype!~"tmpfs|overlay|squashfs"} / node_filesystem_size_bytes{...} < 0.10`
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## What this means here
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Less than 10% free on a real filesystem on a node, for 15 minutes. Read the `mountpoint` label
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first, because on these nodes it tells you which of two very different problems you have.
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**`/data` is the one that matters.** Both the embedded **etcd WAL** (`/data/k3s`) and **every
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Longhorn replica** (`/data/longhorn`) live on that single partition —
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`node_baseline_etcd_source: shared-data-partition`, not a dedicated device, and the exit condition
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for splitting them is still open (`infra/PROD-PROVISIONING.md` §2). If `/data` fills:
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- etcd cannot write its WAL. A control-plane member with a full WAL partition does not degrade
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gracefully; it stops, and this is a 3-member cluster.
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- Longhorn stops being able to hold replicas and volumes go degraded, which triggers rebuilds, which
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need *more* space.
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So `/data` at 10% free is not a warning, it is the last comfortable moment to act.
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**`/` filling up** is usually logs, container images or a stuck journal. Lower stakes, but there is
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history: in the dev era the host root filled to ~99% because VM disks sat under a snapper-snapshotted
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subvolume, and the hypervisor **paused the k3s VMs on I/O error**. Recovery was deleting 11 snapper
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timeline snapshots plus `virsh destroy` on the paused VMs (which were holding rsync-unlinked inodes):
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99% → 30%.
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Longhorn's own guard rails are already tight and are why this alert usually fires before anything
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breaks: `storageReservedPercentageForDefaultDisk: 20`,
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`storageMinimalAvailablePercentage: 25`, `storageOverProvisioningPercentage: 200`.
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## Running the commands in this runbook
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`kubectl` does not work on the operator workstation. The toolchain lives only in the pinned dev
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container, and the host's `k3s-oidc` context hangs on a browser prompt once its token expires —
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that hang is not the cluster being down. Every command below runs as:
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infra/devcontainer/dev.sh run bash -c 'kubectl --context k3s-prod get nodes'
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Always pass `--context k3s-prod` explicitly. `dev.sh` merges both clusters into one kubeconfig and
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defaults its current-context to k3s-**dev**, so a command without `--context` silently answers
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about the wrong cluster. (`CLUSTER=prod infra/devcontainer/dev.sh run kubectl ...` is equivalent.)
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Do not run two `dev.sh` invocations at once — they share one container and interfere.
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USE FULLY-QUALIFIED RESOURCE NAMES, ALWAYS. Three CRDs on this cluster register the kind `Backup`:
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`longhorn.io/v1beta2`, `postgresql.cnpg.io/v1` and `velero.io/v1`. The bare short name resolves to
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Longhorn's, which holds zero objects — so `kubectl get backup -A` prints **"No resources found"** on
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a cluster holding 6 Velero backups and 27 CNPG backups. Verified on prod 2026-09-13. Reading that as
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"the backups are gone" and acting on it turns a false negative into real data loss. Write
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`backups.velero.io`, `backups.postgresql.cnpg.io`, `clusters.postgresql.cnpg.io`,
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`settings.longhorn.io`, `volumes.longhorn.io`, `nodes.longhorn.io`.
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Mutating kubectl (`apply`, `patch`, `annotate`, `rollout`) and `flux reconcile` are blocked for
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agents here: every durable change goes through git (`git push origin main` **is** the deploy).
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Where this runbook gives a mutating command it is for an operator, and it says so.
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## First commands
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Which filesystem, on which node:
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```
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ssh k3s-prod-1 'df -h -x tmpfs -x overlay; echo; du -xh --max-depth=1 /data 2>/dev/null | sort -h | tail -10; echo; du -xh --max-depth=1 / 2>/dev/null | sort -h | tail -10'
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```
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What Longhorn thinks it has:
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```
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infra/devcontainer/dev.sh run bash -c \
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'kubectl --context k3s-prod -n longhorn-system get nodes.longhorn.io -o custom-columns=NAME:.metadata.name,READY:.status.conditions[?\(@.type==\"Ready\"\)].status,SCHED:.spec.allowScheduling; echo; \
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kubectl --context k3s-prod -n longhorn-system get volumes.longhorn.io -o custom-columns=NAME:.metadata.name,SIZE:.spec.size,ACTUAL:.status.actualSize,ROBUST:.status.robustness'
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```
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Journal and image bloat on `/`:
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```
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ssh k3s-prod-1 'sudo journalctl --disk-usage; sudo crictl images | wc -l; sudo du -sh /var/lib/rancher/k3s/agent/containerd 2>/dev/null'
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```
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## Likely causes, most likely first
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### 1. Longhorn replicas grew, or replicas landed here after a rebuild
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Hard node anti-affinity (`replicaSoftAntiAffinity: false`) means one replica per node per volume, but
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`replicaAutoBalance: best-effort` moves them. Prod sits around 269 GiB scheduled against an 829 GiB
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ceiling, so this is rarely tight — but a rebuild storm plus snapshots can spike it.
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Remediation: check for orphaned replicas and stale snapshots in the Longhorn UI. Note
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`orphanAutoDeletion: true` in `platform/longhorn/helmrelease.yaml` **has been silently inert since
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Longhorn 1.12** — it was renamed `orphanResourceAutoDeletion` (a list) and the chart drops unknown
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`defaultSettings` keys with no error. So orphan cleanup is manual. Verify the key's current state in
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the file before you trust it.
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### 2. A CNPG database is not recycling WAL
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The single most dangerous cause, because it is unbounded. With `archive_mode=on` and a failing
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`archive_command`, Postgres **refuses to recycle** unarchived WAL segments and `pg_wal` grows forever
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— on prod's `keycloak-db` that was measured at ~6.8 MiB/h, 17 segments / ~268 MiB, about 29 days to
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fill a 5 GiB PVC. `pg_wal` shares the data PVC (no `walStorage:` is configured on any Cluster).
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Check `/runbooks/cnpg-archiving` **before** you free any space, and **never delete WAL by hand** —
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that destroys the database.
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### 3. Journal / container images on `/`
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`journalctl --vacuum-size=200M` and pruning unused images are safe. Do not prune images for
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workloads that may need to restart while the registry is unreachable.
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### 4. A Velero or CDI staging write
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Velero's kopia uploads and CDI's scratch space both stage locally. `longhorn-scratch`
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(single-replica) exists precisely because the 3-replica default failed the UniFi 60Gi import on
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insufficient storage.
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### 5. The disk is smaller than the platform now needs
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`docs/plans/longhorn-ssd-tiering.md` holds the planned hot tier (~51 GB: Prometheus, CNPG, Loki,
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Gitea). Working set measured ~79 GB against ~323 GB free on SSD, so the "won't fit" blocker was a
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measurement artifact. This is operator planning work, not an incident fix.
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## When to escalate or stop
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- **If the mountpoint is `/data` and free space is under 5%, treat it as an imminent control-plane
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outage** and get the operator. etcd and Longhorn are both on it.
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- **Never delete anything under `/data/longhorn` or a Postgres `pg_wal` directory by hand.** Both are
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irreversible. Free space elsewhere, or fix the cause.
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- **Do not `kubectl drain`** the node to move load off it — this cluster does not drain.
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- If the cause is a CNPG archive failure, this runbook is the wrong one: go to
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`/runbooks/cnpg-archiving`, which is the actual fix.
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---
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Source of truth: `runbooks/node-disk.md`. Index: `/runbooks/`
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Records: `DECISIONS-LOG.md` "Disk/drive incident + k3s relocated to NVMe (2026-08-22)";
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`platform/cnpg/alerts.yaml` header (the WAL disk-full clock).
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