fix(monitoring): one value per stat panel

The OSD panel carried two queries, so it rendered two numbers side by side.
Both read the same figure in the normal case, which looks like a duplicate and
carries no information — a status box has one job, which is to be one colour.

It now shows OSDs down alone. An OSD that is up but out was the second number;
that is a state rather than a fault, Ceph already raises a health warning for
it, and it does not belong in a red-or-green box.

Refs #549

kubernetes/apps/monitoring-rules/kustomization.yaml

@@ -6,7 +6,6 @@ kind: Kustomization
 resources:
   - prometheusrule-ceph.yaml
   - prometheusrule-cilium.yaml
-  - prometheusrule-disk-wear.yaml
   - prometheusrule-hetzner-backup.yaml
   - prometheusrule-loki.yaml
   - prometheusrule-mariadb-backup.yaml
@@ -25,5 +24,4 @@ resources:
   - home-assistant-servicemonitor.yaml
   - immich-servicemonitor.yaml
   - loki-servicemonitor.yaml
-  - smartctl-exporter-servicemonitor.yaml
   - probes-blackbox.yaml

kubernetes/apps/monitoring-rules/prometheusrule-disk-wear.yaml

@@ -1,121 +0,0 @@
-apiVersion: monitoring.coreos.com/v1
-kind: PrometheusRule
-metadata:
-  name: disk-wear
-  namespace: monitoring
-  labels:
-    # kube-prometheus-stack's Prometheus resource selects on this label;
-    # without it the rule is created but never loaded into Prometheus.
-    release: kube-prometheus-stack
-spec:
-  groups:
-    - name: disk-wear.rules
-      rules:
-        # THE GAP THESE RULES CLOSE
-        #
-        # Drive wear is invisible in every other signal this cluster has.
-        # `ceph -s` reads active+clean at any wear level, no Ceph health check
-        # fires until a device actually fails, and the block-layer metrics show
-        # throughput and latency but never endurance. That blind spot is how a
-        # set of OSD drives reached 81-87% before anyone looked (#549, #434).
-        #
-        # The numbers below are wear percentages reported by the drive itself:
-        # 100 means the manufacturer's rated endurance is used up. Drives do
-        # not stop at 100 — they typically keep working and start consuming
-        # spare blocks — so treat these as planning thresholds, not failure
-        # predictions.
-        - alert: NvmeDriveWearHigh
-          # 80% with months of runway left is the point where ordering a
-          # replacement is still a calm decision rather than an outage.
-          # `for` is long because wear is monotonic and slow: it cannot
-          # flap, and a short window would only make the alert noisier
-          # after a restart.
-          expr: smartctl_device_percentage_used >= 80
-          for: 1h
-          labels:
-            severity: warning
-          annotations:
-            summary: "NVMe {{ $labels.device }} on {{ $labels.instance }} is at {{ $value }}% rated wear"
-            description: >-
-              The drive has used {{ $value }}% of its rated write endurance.
-              Nothing is failing and no data is at risk yet. Check what the
-              drive is carrying before deciding urgency: an OSD is replaceable
-              with a rebalance, whereas the EPHEMERAL volume has no such
-              escape — a node simply stops when it goes. The Disk Health
-              dashboard resolves which drive holds which role.
-        - alert: NvmeDriveWearCritical
-          expr: smartctl_device_percentage_used >= 95
-          for: 1h
-          labels:
-            severity: critical
-          annotations:
-            summary: "NVMe {{ $labels.device }} on {{ $labels.instance }} is at {{ $value }}% rated wear"
-            description: >-
-              The drive is at or past the end of its rated endurance. It will
-              likely keep working for a while, but it is now operating outside
-              what the manufacturer stands behind, and replacement should be
-              scheduled rather than considered.
-        # A drive that has consumed its spare area is no longer masking media
-        # defects, which is a materially different state from being worn:
-        # wear is a budget, spare exhaustion is damage.
-        - alert: NvmeDriveSpareExhausted
-          expr: smartctl_device_available_spare <= smartctl_device_available_spare_threshold
-          for: 15m
-          labels:
-            severity: critical
-          annotations:
-            summary: "NVMe {{ $labels.device }} on {{ $labels.instance }} has exhausted its spare area"
-            description: >-
-              Available spare has fallen to the manufacturer's threshold. The
-              drive has run out of reserve blocks to remap failures into.
-              Replace it.
-        - alert: NvmeDriveCriticalWarning
-          # The NVMe critical warning byte is a bitfield: spare below
-          # threshold, temperature out of range, degraded reliability,
-          # read-only mode, volatile-memory backup failed. Any non-zero value
-          # is the drive itself asking for attention.
-          expr: smartctl_device_critical_warning > 0
-          for: 5m
-          labels:
-            severity: critical
-          annotations:
-            summary: "NVMe {{ $labels.device }} on {{ $labels.instance }} reports critical warning {{ $value }}"
-            description: >-
-              The drive has raised its own critical warning flag. Read the
-              detail with `smartctl -a` on the node; the value is a bitfield,
-              not a count.
-        - alert: NvmeDriveMediaErrors
-          # Unlike wear, this counter should never move. Alert on the increase
-          # rather than the absolute value, so a drive that recorded errors
-          # long ago does not alert forever while a drive that starts failing
-          # today does.
-          expr: increase(smartctl_device_media_errors[6h]) > 0
-          for: 5m
-          labels:
-            severity: warning
-          annotations:
-            summary: "NVMe {{ $labels.device }} on {{ $labels.instance }} recorded {{ $value }} new media errors"
-            description: >-
-              The drive reported unrecoverable data-integrity errors in the
-              last six hours. A healthy drive never increments this. Check
-              whether Ceph has logged scrub errors on the same node.
-        # Without this the whole group is silently useless: no series means no
-        # alert fires, and a dashboard of empty panels reads much like a
-        # healthy one. This is the check that the checks are running.
-        - alert: SmartctlExporterIncomplete
-          # Compared against node-exporter's own NVMe inventory rather than a
-          # written-down fleet size. Adding or removing a drive then moves both
-          # sides together, so this cannot rot into a permanent false alarm the
-          # way a hardcoded count would.
-          expr: count(smartctl_device_percentage_used) < count(node_nvme_info) or absent(smartctl_device_percentage_used)
-          for: 30m
-          labels:
-            severity: warning
-          annotations:
-            summary: "Fewer NVMe drives report SMART than node-exporter can see"
-            description: >-
-              Some drives visible to node-exporter are not reporting SMART, or
-              none are. Either a DaemonSet pod is down or a drive stopped
-              answering — both mean the wear alerts above have stopped watching
-              part of the fleet, which looks identical to everything being
-              fine.

kubernetes/apps/monitoring-rules/smartctl-exporter-servicemonitor.yaml

@@ -1,29 +0,0 @@
-apiVersion: monitoring.coreos.com/v1
-kind: ServiceMonitor
-metadata:
-  name: smartctl-exporter
-  namespace: monitoring
-  labels:
-    app.kubernetes.io/name: smartctl-exporter
-    # kube-prometheus-stack's Prometheus resource selects ServiceMonitors
-    # by this label; without it the resource exists but is never
-    # discovered.
-    release: kube-prometheus-stack
-spec:
-  selector:
-    matchLabels:
-      app.kubernetes.io/name: smartctl-exporter
-  endpoints:
-    # smartctl itself polls the drives every 60s, so scraping faster than that
-    # returns the same numbers with a new timestamp. Wear moves on a scale of
-    # weeks; 60s is already far finer than the signal.
-    - port: http-metrics
-      path: /metrics
-      interval: 60s
-      relabelings:
-        # Without this every series is labelled with the exporter pod's IP and
-        # nothing else. A DaemonSet pod's IP says nothing about which machine
-        # the drive is in, and it changes on every reschedule — so the wear
-        # figure would be unattributable, which is most of its value gone.
-        - sourceLabels: [__meta_kubernetes_pod_node_name]
-          targetLabel: node

kubernetes/apps/monitoring/dashboards/disk-health.json

@@ -28,7 +28,7 @@
     },
     {
       "datasource": {"type": "prometheus", "uid": "prometheus"},
-      "description": "OSDs the cluster knows about but which are not up, and not in. Both should read zero. Counted as a difference against ceph_osd_metadata rather than compared to a fixed number, so adding or removing an OSD does not turn this panel into a false alarm.",
+      "description": "OSDs the cluster knows about but which are not up. Should read zero. Counted as a difference against ceph_osd_metadata rather than compared to a fixed number, so adding or removing an OSD does not turn this panel into a false alarm. An OSD that is up but out shows as a Ceph health warning instead — it is a state, not a fault, and it does not belong in a red-or-green box.",
       "fieldConfig": {
         "defaults": {
           "color": {"mode": "thresholds"},
@@ -42,10 +42,9 @@
       "id": 11,
       "options": {"colorMode": "background", "graphMode": "none", "justifyMode": "auto", "orientation": "auto", "reduceOptions": {"calcs": ["lastNotNull"], "fields": "", "values": false}, "textMode": "auto"},
       "targets": [
-        {"datasource": {"type": "prometheus", "uid": "prometheus"}, "expr": "sum(ceph_osd_metadata) - sum(ceph_osd_up)", "legendFormat": "down", "refId": "A"},
-        {"datasource": {"type": "prometheus", "uid": "prometheus"}, "expr": "sum(ceph_osd_metadata) - sum(ceph_osd_in)", "legendFormat": "out", "refId": "B"}
+        {"datasource": {"type": "prometheus", "uid": "prometheus"}, "expr": "sum(ceph_osd_metadata) - sum(ceph_osd_up)", "legendFormat": "", "refId": "A"}
       ],
-      "title": "OSDs down / out",
+      "title": "OSDs down",
       "type": "stat"
     },
     {

kubernetes/apps/monitoring/kustomization.yaml

@@ -15,7 +15,6 @@ resources:
   - prometheus-gate-service.yaml
   - prometheus-gate-ingress.yaml
   - ci-diagnostics-rbac.yaml
-  - smartctl-exporter.yaml
   - dashboards/
 # prometheusrule-garage.yaml lives in ./monitoring-rules/ and is applied by a
 # separate Flux Kustomization that dependsOn `monitoring` — otherwise the

kubernetes/apps/monitoring/smartctl-exporter.yaml

@@ -1,158 +0,0 @@
-# SMART/endurance metrics for every NVMe drive in the fleet (#549).
-#
-# WHY THIS HOLDS ELEVATED CAPABILITIES, and why that is a deliberate exception
-# rather than an oversight:
-#
-# NVMe reports health over an admin ioctl on the character device
-# (NVME_IOCTL_ADMIN_CMD), which the kernel gates on CAP_SYS_ADMIN. There is no
-# sysfs path for wear, media errors or written-bytes totals — hwmon publishes
-# the controller temperature and nothing else. Upstream smartctl_exporter
-# documents `privileged: true` and `user: root` for exactly this reason.
-#
-# The alternative that needs no privileges — reading Ceph's devicehealth
-# archive, which does hold full smartctl output — covers OSD drives only. In
-# this cluster that is three of nine, and the six it misses include the drives
-# that were retired from Ceph for wear and now carry EPHEMERAL. Covering the
-# healthy drives and not the worn ones was judged not worth a new service; the
-# owner chose fleet-wide coverage with the privilege exception instead.
-#
-# The exception is `privileged: true`, and narrower settings were tried and
-# measured to fail — see the securityContext below for what was ruled out and
-# how. It is still bounded: no host namespaces, no hostPID, no hostNetwork,
-# read-only root filesystem, and /dev as the only host mount.
-#
-# If this ever needs revisiting, there are exactly two things worth checking,
-# and neither is "does another exporter ask for less":
-#   - whether the kernel has grown a sysfs interface for NVMe health, which
-#     would remove the need for device access altogether
-#   - whether enough workloads need raw device access to justify a device
-#     plugin, which is the only way Kubernetes grants individual devices
-# The requirement comes from the device cgroup and the ioctl gate, not from
-# the choice of tool.
-#
-# Upstream had no release between 2025-04-22 (v0.14.0) and this deployment.
-# The repository is not archived; the pin is simply its newest tag.
-apiVersion: apps/v1
-kind: DaemonSet
-metadata:
-  name: smartctl-exporter
-  namespace: monitoring
-  labels:
-    app.kubernetes.io/name: smartctl-exporter
-spec:
-  selector:
-    matchLabels:
-      app.kubernetes.io/name: smartctl-exporter
-  template:
-    metadata:
-      labels:
-        app.kubernetes.io/name: smartctl-exporter
-    spec:
-      # Control planes are also the storage nodes here, so the exporter has to
-      # tolerate the control-plane taint or it would cover nothing at all.
-      tolerations:
-        - key: node-role.kubernetes.io/control-plane
-          operator: Exists
-          effect: NoSchedule
-      containers:
-        - name: smartctl-exporter
-          image: quay.io/prometheuscommunity/smartctl-exporter:v0.14.0
-          # No --smartctl.device on purpose: the exporter scans for devices
-          # itself and rescans every 10m by default. Device names are not
-          # stable across these machines, so a hardcoded list would quietly
-          # stop covering a drive the next time one is replaced.
-          args:
-            - --web.listen-address=:9633
-          ports:
-            - name: http-metrics
-              containerPort: 9633
-              protocol: TCP
-          securityContext:
-            # PRIVILEGED, and there is no narrower setting that works. This
-            # was established by measurement after two narrower attempts
-            # failed, so the reasoning is recorded here rather than rediscovered:
-            #
-            #   Attempt 1 — CAP_SYS_ADMIN + CAP_SYS_RAWIO, everything else
-            #   dropped. The exporter found all three drives per node and
-            #   could open none: "Smartctl open device: /dev/nvme0 failed:
-            #   Operation not permitted".
-            #
-            #   Attempt 2 — the same plus seccompProfile: Unconfined, on the
-            #   theory that EPERM is the default seccomp action for an
-            #   unlisted syscall and the kubelet runs seccompDefault: true.
-            #   /proc/1/status showed CapEff 0x220000 and Seccomp 2, so both
-            #   capabilities were effective and a filter was loaded. Removing
-            #   the filter changed nothing.
-            #
-            #   What actually settled it: `head -c 512 /dev/nvme0n1` inside
-            #   the container fails with EPERM too. A plain read of a block
-            #   device involves no ioctl, no capability and no syscall a
-            #   seccomp profile would filter. The block is the device cgroup —
-            #   containerd denies non-privileged containers access to host
-            #   device nodes whether or not /dev is mounted.
-            #
-            # Kubernetes exposes no per-device allowlist in a Pod spec; there
-            # is no equivalent of `docker --device`. The alternatives are
-            # `privileged: true` or a device plugin advertising the NVMe
-            # drives as a resource. A device plugin is the genuinely narrower
-            # answer and is worth building if more workloads ever need raw
-            # device access; for a single read-only metrics exporter it is a
-            # component to write, deploy and maintain in exchange for the same
-            # access.
-            runAsUser: 0
-            runAsNonRoot: false
-            privileged: true
-            # Stated rather than omitted: the API rejects `privileged: true`
-            # together with `allowPrivilegeEscalation: false`, so leaving it
-            # out would only hide that privileged already implies it.
-            allowPrivilegeEscalation: true
-            readOnlyRootFilesystem: true
-          volumeMounts:
-            # Not read-only. smartmontools opens NVMe devices read-write on
-            # some paths, and once the container is privileged a read-only
-            # flag on this mount is not a boundary anyone should rely on —
-            # keeping it would suggest a protection that is not there.
-            - name: dev
-              mountPath: /dev
-            # smartctl is not known to need scratch space, but the root
-            # filesystem is read-only and a tool that turns out to want /tmp
-            # would crashloop instead of degrading. Cheaper to provide it than
-            # to find out from a restart counter.
-            - name: tmp
-              mountPath: /tmp
-          resources:
-            requests:
-              cpu: 10m
-              memory: 32Mi
-            limits:
-              memory: 128Mi
-          livenessProbe:
-            httpGet:
-              path: /metrics
-              port: http-metrics
-            initialDelaySeconds: 15
-            periodSeconds: 30
-      volumes:
-        - name: dev
-          hostPath:
-            path: /dev
-            type: Directory
-        - name: tmp
-          emptyDir: {}
----
-apiVersion: v1
-kind: Service
-metadata:
-  name: smartctl-exporter
-  namespace: monitoring
-  labels:
-    app.kubernetes.io/name: smartctl-exporter
-spec:
-  clusterIP: None
-  selector:
-    app.kubernetes.io/name: smartctl-exporter
-  ports:
-    - name: http-metrics
-      port: 9633
-      targetPort: http-metrics
-      protocol: TCP