jakman85andClaude Opus 5
a92fa11701
An alert rule whose metric is never scraped is not a broken alert, it is an ABSENT
alert that reads as a present one. `longhorn_volume_robustness == 2` over a TSDB
with no longhorn_* series returns no vector: permanently quiet, permanently
"healthy", indistinguishable from a correct rule. It survives review (the PromQL is
right), it survives `promtool test rules` (the unit test supplies the series
itself), and it appears on no dashboard.
VERIFIED ABSENT ON PROD before this change (re-verified 2026-09-13 21:0xZ, ~15h
after the first audit, because a stale reading is not evidence):
count(longhorn_volume_robustness) => (empty) 4 rules inert
count({__name__=~"certmanager.*"}) => (empty) 3 rules inert
count(hubble_drop_total) / {__name__=~"cilium.*"} => (empty) 1 rule inert
count by (job) (up) => 20 jobs, none of them
Longhorn, cert-manager,
Cilium or Hubble
Consequence: storage health was unmonitored on the cluster whose prod-1 had just
had a failing SSD, and TLS expiry was unmonitored with the live `wildcard-home`
wildcard 89 days from expiry on an ACME DNS-01 renewal that can fail silently.
WHAT THIS CHANGES
* platform/longhorn: `metrics.serviceMonitor.enabled: true` (the supported chart
way — rendering longhorn 1.12.1 emits exactly 1 ServiceMonitor with the flag and
0 without), plus networkpolicy-metrics.yaml. The NetworkPolicy is LOAD-BEARING,
not belt-and-braces: measured with the monitor applied and no allowance, all 3
targets were DISCOVERED and every scrape failed `context deadline exceeded`
after 10.0s — a drop, not a refusal — while curling the endpoint from inside
the manager pod returned 200 in 0.031s. Longhorn 1.12.1 ships 6 NetworkPolicies
of its own, guarded on `networkPolicies.restrictInternalTraffic` (default TRUE)
and NOT on `networkPolicies.enabled`, so they are effectively unconditional and
the manager policy admits only same-namespace Longhorn components. The one-line
alternative (restrictInternalTraffic: false) was rejected: it deletes the
internal-traffic restriction across all six components to open one port to one
namespace, trading an R-SEC-02 control for an observability one when the two do
not conflict. This policy is Ingress-only, ns monitoring -> app=longhorn-manager,
TCP 9500 only; 9502/9503 (webhook, recovery backend) stay closed.
* platform/cert-manager: `prometheus.servicemonitor.enabled: true`. Chart default
already serves 9402; only the monitor was missing. No NetworkPolicy needed —
neither ns cert-manager nor ns monitoring carries one. NOT paired with
prometheus.podmonitor.enabled: the chart calls `fail` if both are set.
* platform/kubevirt: KubeVirtVMLaunchFailing queried
`kubevirt_vmi_phase_count{phase="Failed"}`, which DOES NOT EXIST on the deployed
KubeVirt — a different flavour of the same defect, with the scrape target up and
healthy. Prod has only `kubevirt_vmi_info` and `kubevirt_vmi_number_of_outdated`;
the only phase-bearing names are the phase_transition_time histograms. Corrected
to `kubevirt_vmi_info{phase="failed"}` — LOWERCASE, because KubeVirt lowercases
the value (observed `phase="running"` for the unifi VMI) and a capital-F matcher
would select nothing and be exactly as inert.
PROVEN, NOT ASSERTED. The rendered ServiceMonitors were applied to prod by hand and
the metrics observed to land, then REMOVED again so the merge's Helm upgrade creates
and owns them rather than colliding with an unowned object:
count(up{job="longhorn-backend"}) => 3 (all three managers, up==1)
count({__name__=~"longhorn.*"}) => 8717 (was empty)
count(longhorn_volume_robustness) => 44
up{namespace="cert-manager"} => 3 targets, all 1
count({__name__=~"certmanager.*"}) => 104 (was empty)
wildcard-home days to expiry => 89.2, ready_status{condition="True"}=1
All 58 alert rules in the repo were then evaluated against prod one by one: every
one returns a result without error, and exactly ONE fires.
TRIAGE OF THE ONE NEWLY-FIRING ALERT — A TRUE POSITIVE, NOT TUNED AWAY.
LonghornVolumeCapacityHigh on the Prometheus TSDB volume:
`longhorn_volume_actual_size_bytes / longhorn_volume_capacity_bytes` = 0.971
(48.6 GiB allocated of 50 GiB) while the kubelet's view of the same filesystem is
only 20.4% used. Longhorn is not reclaiming freed blocks, so ~48.6 GiB x 3 replicas
is committed for ~10 GiB of real data. On a cluster whose failure mode is disk
pressure and whose etcd WAL shares a spindle with Longhorn, that is worth knowing
and was invisible until now. The threshold is left alone; the follow-up is
filesystem trim, not a bigger number.
THE GUARD (conformance/tests/l0-static/alert-metrics-have-scrape-targets)
Whole-repo L0 invariant, 118 assertions. It crosses from each alert to the scrape
config that makes its metric exist: every metric name is claimed by exactly one
declared owner, and each owner's enabling declaration is re-proven against the
working tree on every gate run, including the negative conditions that defeat an
enablement without deleting it. `up{job="X"}` is audited on its own axis, because
`up` always exists: where this repo authors a Service and a ServiceMonitor in the
same file, the monitor's endpoint port must be a port that Service defines.
It DECLARES conformance.home.k3s/scope: "whole-repo" and adds NO ci/l0.sh stage —
the whole-repo-invariants-wired meta-test fails the gate if one reappears.
PROVEN ABLE TO FAIL, five ways, each reverted:
1. an alert on a fabricated metric -> FAIL "claimed by NO entry"
2. longhorn metrics.serviceMonitor removed -> FAIL "no longer matches"
3. networkpolicy-metrics.yaml unwired -> FAIL "the monitor alone is NOT enough"
4. cert-manager podmonitor also enabled -> FAIL "FORBIDDEN pattern"
5. a register entry made stale / removed -> FAIL in both directions
TWO SHRINK-ONLY REGISTERS, because a blanket fail would make the gate red until
work that is not this change lands, and a disabled gate protects nothing:
* KNOWN_UNWIRED_METRICS (1): hubble_drop_total. See below.
* KNOWN_UNWIRED_JOBS (12): every apps/* `<app>-down` SLI rule is ALSO inert, and
this was found by the re-audit, not previously known. The rendered
ServiceMonitors name `port: metrics` and NOT ONE of the twelve app Services
defines a port of that name (zero occurrences of `name: metrics` across all
twelve manifests); prod confirms none of the twelve jobs appears in `up`. This
is the nastiest variant of the class: `up` exists in abundance so nothing looks
wrong, and PrometheusTargetsMissing cannot see it either, because a target that
was never discovered has no up series to be 0. Closing it needs an exporter per
app (Plex, Pi-hole, Jackett, qBittorrent, Sonarr, Radarr, Seerr speak no
Prometheus) — except keycloak, where the live jobs are keycloak-service /
keycloak-discovery and the rule is a rename away from being live.
NOT DONE HERE, DELIBERATELY: Hubble. hubble.metrics.enabled RECONFIGURES THE CNI —
it opens 9965 on every cilium-agent and rolls the DaemonSet across all three nodes,
serialised by this repo's own maxUnavailable: 1 (set after the 2026-09-01
k8sServiceHost outage, where a CNI roll deadlocked 2 of 3 agents). It also needs a
matching edit to roles/cilium/templates/cilium-values.yaml.j2 in the same commit,
because platform/cilium/helmrelease.yaml carries a [parity] contract against it and
a rebuilt node would otherwise bootstrap a CNI config that disagrees with the
reconciled one. Recommended as its own change on the cilium Kustomization, with the
Ansible parity edit, a narrow labelsContext, and a one-node canary — not smuggled in
here.
ALSO FOUND, NOT FIXED HERE: kube-state-metrics is OOMKilled every ~10 minutes on
prod (90 restarts in 16h against a 128Mi limit) while its logs show the
custom-resource-state factory reloading every 3 seconds. Thirteen alert rules read
kube_* metrics, so those rules are INTERMITTENTLY inert — the same defect class,
arriving through a crashloop rather than a missing monitor. Needs its own change.
Co-Authored-By: Claude Opus 5 <[email protected]>
89 lines
5.8 KiB
YAML
89 lines
5.8 KiB
YAML
---
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# KubeVirt platform-health alerts (docs/10, R-OBS-04): "VM crash-loops / failed launches" as a
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# first-class platform signal, alongside the node/Longhorn/Flux/cert/VPN/backup/identity rules in
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# platform/monitoring/alerts.yaml. PrometheusRule is a CR of the monitoring.coreos.com CRD installed
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# by kube-prometheus-stack, so this is applied by the `platform-config` Flux Kustomization (dependsOn:
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# platform), NOT the controllers pass (F-MON1) — identical wiring to platform/monitoring/alerts.yaml.
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#
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# The `release: kube-prometheus-stack` label makes the operator's Prometheus select these rules. Metric
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# names follow KubeVirt's `kubevirt_*` series; where a series depends on the deployed exporter it is
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# flagged to confirm at bring-up (same convention as platform/monitoring/alerts.yaml).
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apiVersion: monitoring.coreos.com/v1
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kind: PrometheusRule
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metadata:
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name: platform-health-kubevirt
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namespace: monitoring
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labels:
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release: kube-prometheus-stack
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platform-health: "true"
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spec:
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groups:
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- name: platform-health.kubevirt
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rules:
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# Failed launches: a VMI that reached the Failed phase (scheduling/launch/qemu failure). Any
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# sustained Failed VMI is page-worthy — the IaaS path is broken for that workload.
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#
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# METRIC CORRECTED 2026-09-13 (was `kubevirt_vmi_phase_count{phase="Failed"}`). That series
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# DOES NOT EXIST on the deployed KubeVirt, so this rule was structurally INERT — unlike the
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# Longhorn/cert-manager/Flux gaps in the same audit, NOT for want of a scrape target: the
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# `kubevirt-prometheus-metrics` job is up and its siblings below (virt_api_ready_status,
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# virt_controller_ready_status, cdi_import_pods_high_restart) all resolve. KubeVirt simply
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# retired the phase-count gauge in favour of an info-style series carrying `phase` as a label.
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# VERIFIED live on prod 2026-09-13:
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# count(kubevirt_vmi_phase_count) => (empty)
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# count(kubevirt_vmi_info) => 1
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# kubevirt_vmi_info{...,name="unifi",namespace="unifi",phase="running",...} => 1
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# Note `phase="running"` — KubeVirt LOWERCASES the phase in this label, so the matcher is
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# "failed", not "Failed". A capital-F matcher here would silently select nothing and leave the
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# rule just as inert as the metric name did; that is the whole point of this class of defect.
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- alert: KubeVirtVMLaunchFailing
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expr: sum by (namespace) (kubevirt_vmi_info{phase="failed"}) > 0
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for: 5m
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labels:
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severity: critical
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annotations:
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summary: "KubeVirt VM(s) failing to launch in {{ $labels.namespace }}"
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description: "One or more VirtualMachineInstances are in the Failed phase in namespace {{ $labels.namespace }} for 5m — a failed VM launch (image import, scheduling, or qemu error). Check `kubectl get vmi -n {{ $labels.namespace }}` and the virt-launcher pod events."
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runbook_url: "https://${BASE_DOMAIN}/runbooks/kubevirt-launch-failed"
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# Crash-loop: the VM's virt-launcher pod is restarting repeatedly (guest kernel panic, OOM, or a
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# crashing qemu). >3 restarts in 15m is a crash-loop, not a one-off reboot.
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- alert: KubeVirtVMCrashLooping
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expr: |
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increase(kube_pod_container_status_restarts_total{pod=~"virt-launcher-.*"}[15m]) > 3
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for: 10m
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labels:
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severity: warning
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annotations:
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summary: "KubeVirt VM crash-looping: {{ $labels.namespace }}/{{ $labels.pod }}"
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description: "virt-launcher pod {{ $labels.namespace }}/{{ $labels.pod }} has restarted more than 3 times in 15m — the guest VM is crash-looping (panic / OOM / qemu crash)."
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runbook_url: "https://${BASE_DOMAIN}/runbooks/kubevirt-crashloop"
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# Control plane down: no virt-controller or virt-api replica reports ready, so no VM lifecycle
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# operations can proceed. The metrics are `kubevirt_virt_{controller,api}_ready_status` (per-pod
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# 1=ready); sum()==0 means every replica is unready. The absent() clause also fires if the whole
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# KubeVirt metrics target disappears — its scrape job label is `kubevirt-prometheus-metrics` (the
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# Service name), NOT `kubevirt`.
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- alert: KubeVirtControlPlaneDown
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expr: |
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(sum(kubevirt_virt_controller_ready_status) == 0)
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or (sum(kubevirt_virt_api_ready_status) == 0)
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or (absent(up{job="kubevirt-prometheus-metrics"} == 1))
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for: 10m
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labels:
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severity: critical
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annotations:
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summary: "KubeVirt control plane degraded"
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description: "The KubeVirt control plane (virt-controller/virt-api) is not ready or its metrics are absent for 10m — VM lifecycle operations (create/start/stop) will fail (docs/06)."
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runbook_url: "https://${BASE_DOMAIN}/runbooks/kubevirt-control-plane"
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# CDI import stuck: a DataVolume import/clone still in flight after 30m blocks the VM it backs.
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# kubevirt_cdi_import_pods_high_restart counts importer pods stuck restarting; a positive value
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# sustained means an import is not progressing (metric name confirmed against CDI at bring-up).
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- alert: CDIDataVolumeImportStuck
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expr: sum(kubevirt_cdi_import_pods_high_restart) > 0
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for: 30m
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labels:
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severity: warning
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annotations:
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summary: "CDI DataVolume import stuck: {{ $labels.namespace }}/{{ $labels.name }}"
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description: "A CDI DataVolume import/clone in {{ $labels.namespace }} has not completed after 30m — the VM disk it backs cannot start. Check the importer pod (often an egress/default-deny block on the image source, or a slow mirror)."
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runbook_url: "https://${BASE_DOMAIN}/runbooks/cdi-import-stuck"
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