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/dashboards/disk-health.json

@@ -1,6 +1,6 @@
 {
   "annotations": {"list": []},
-  "description": "NVMe throughput, latency and temperature per node. Every panel joins node_disk_* to node_nvme_info and node_uname_info on purpose: device names are NOT stable across nodes (nvme0 is the Kingston system disk on k8s-1 and k8s-3, but the Crucial on k8s-2), so a legend keyed on the device alone compares different hardware. Endurance/wear is deliberately absent — see the note at the bottom and issue #549.",
+  "description": "NVMe health and performance per node. The top row answers 'is anything wrong'; the graphs below answer 'why'. Panels resolve each drive through node_nvme_info and node_uname_info rather than plotting the Linux device name, because NVMe enumeration order is not guaranteed to agree across machines — the same name can be a different drive on the next node. Which drive currently holds which role is in the inventory table, deliberately not in this text. Endurance/wear is absent; see the note at the bottom and issue #549.",
   "editable": true,
   "fiscalYearStartMonth": 0,
   "graphTooltip": 1,
@@ -9,7 +9,89 @@
   "panels": [
     {
       "datasource": {"type": "prometheus", "uid": "prometheus"},
-      "description": "Which physical drive is which, resolved live rather than written down. The OSD column comes from ceph_disk_occupation, so it follows Rook instead of restating a device list that would go stale the next time a drive is swapped.",
+      "description": "Ceph's overall verdict. A HEALTH_WARN is frequently raised by something unrelated to the drives, so read the detail before treating it as a storage problem.",
+      "fieldConfig": {
+        "defaults": {
+          "color": {"mode": "thresholds"},
+          "mappings": [{"options": {"0": {"color": "green", "index": 0, "text": "HEALTH_OK"}, "1": {"color": "orange", "index": 1, "text": "HEALTH_WARN"}, "2": {"color": "red", "index": 2, "text": "HEALTH_ERR"}}, "type": "value"}],
+          "thresholds": {"mode": "absolute", "steps": [{"color": "green", "value": null}, {"color": "orange", "value": 1}, {"color": "red", "value": 2}]},
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 6, "x": 0, "y": 0},
+      "id": 10,
+      "options": {"colorMode": "background", "graphMode": "none", "justifyMode": "auto", "orientation": "auto", "reduceOptions": {"calcs": ["lastNotNull"], "fields": "", "values": false}, "textMode": "auto"},
+      "targets": [{"datasource": {"type": "prometheus", "uid": "prometheus"}, "expr": "ceph_health_status", "legendFormat": "", "refId": "A"}],
+      "title": "Ceph health",
+      "type": "stat"
+    },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "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"},
+          "mappings": [],
+          "thresholds": {"mode": "absolute", "steps": [{"color": "green", "value": null}, {"color": "red", "value": 1}]},
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 6, "x": 6, "y": 0},
+      "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": "", "refId": "A"}
+      ],
+      "title": "OSDs down",
+      "type": "stat"
+    },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "description": "Raw Ceph capacity in use. The cluster average is the optimistic number: Ceph stops writing when a single OSD crosses the full ratio, so per-OSD headroom is what actually bites.",
+      "fieldConfig": {
+        "defaults": {
+          "color": {"mode": "thresholds"},
+          "mappings": [],
+          "max": 1,
+          "min": 0,
+          "thresholds": {"mode": "absolute", "steps": [{"color": "green", "value": null}, {"color": "orange", "value": 0.75}, {"color": "red", "value": 0.85}]},
+          "unit": "percentunit"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 6, "x": 12, "y": 0},
+      "id": 12,
+      "options": {"colorMode": "background", "graphMode": "area", "justifyMode": "auto", "orientation": "auto", "reduceOptions": {"calcs": ["lastNotNull"], "fields": "", "values": false}, "textMode": "auto"},
+      "targets": [{"datasource": {"type": "prometheus", "uid": "prometheus"}, "expr": "ceph_cluster_total_used_bytes / ceph_cluster_total_bytes", "legendFormat": "", "refId": "A"}],
+      "title": "Ceph capacity used",
+      "type": "stat"
+    },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "description": "Fullest EPHEMERAL volume across the fleet — Talos's /var, holding container images, pod scratch space and kubelet state. A full /var takes the node down, and unlike Ceph nothing rebalances away from it.",
+      "fieldConfig": {
+        "defaults": {
+          "color": {"mode": "thresholds"},
+          "mappings": [],
+          "max": 1,
+          "min": 0,
+          "thresholds": {"mode": "absolute", "steps": [{"color": "green", "value": null}, {"color": "orange", "value": 0.7}, {"color": "red", "value": 0.85}]},
+          "unit": "percentunit"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 6, "x": 18, "y": 0},
+      "id": 13,
+      "options": {"colorMode": "background", "graphMode": "area", "justifyMode": "auto", "orientation": "auto", "reduceOptions": {"calcs": ["lastNotNull"], "fields": "", "values": false}, "textMode": "auto"},
+      "targets": [{"datasource": {"type": "prometheus", "uid": "prometheus"}, "expr": "max(1 - node_filesystem_avail_bytes{mountpoint=\"/var\"} / node_filesystem_size_bytes{mountpoint=\"/var\"})", "legendFormat": "", "refId": "A"}],
+      "title": "EPHEMERAL used (worst node)",
+      "type": "stat"
+    },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "description": "Which physical drive is which, resolved live rather than written down — this table is the answer to 'what is in the machines', so that no panel description has to be. The OSD column is joined from ceph_disk_occupation, so it follows Rook; a drive with no OSD is carrying either the system disk or EPHEMERAL.",
       "fieldConfig": {
         "defaults": {
           "color": {"mode": "thresholds"},
@@ -19,13 +101,13 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 9, "w": 24, "x": 0, "y": 0},
+      "gridPos": {"h": 9, "w": 24, "x": 0, "y": 4},
       "id": 1,
       "options": {"cellHeight": "sm", "footer": {"countRows": false, "fields": "", "reducer": ["sum"], "show": false}, "showHeader": true, "sortBy": [{"desc": false, "displayName": "node"}]},
       "targets": [
         {
           "datasource": {"type": "prometheus", "uid": "prometheus"},
-          "expr": "node_nvme_info * on (instance) group_left(nodename) node_uname_info",
+          "expr": "(label_replace(node_nvme_info * on (instance) group_left(nodename) node_uname_info, \"nvmedev\", \"$1\", \"device\", \"(nvme[0-9]+)\") * on (nodename, nvmedev) group_left(ceph_daemon) label_replace(label_replace(ceph_disk_occupation, \"nodename\", \"$1\", \"instance\", \"(.*)\"), \"nvmedev\", \"$1\", \"devices\", \"(nvme[0-9]+)n[0-9]+\")) or (label_replace(node_nvme_info * on (instance) group_left(nodename) node_uname_info, \"nvmedev\", \"$1\", \"device\", \"(nvme[0-9]+)\") unless on (nodename, nvmedev) label_replace(label_replace(ceph_disk_occupation, \"nodename\", \"$1\", \"instance\", \"(.*)\"), \"nvmedev\", \"$1\", \"devices\", \"(nvme[0-9]+)n[0-9]+\"))",
           "format": "table",
           "instant": true,
           "legendFormat": "",
@@ -37,9 +119,9 @@
         {
           "id": "organize",
           "options": {
-            "excludeByName": {"Time": true, "Value": true, "__name__": true, "cntlid": true, "container": true, "endpoint": true, "instance": true, "job": true, "namespace": true, "pod": true, "service": true, "domainname": true, "machine": true, "release": true, "sysname": true, "version": true, "state": true},
+            "excludeByName": {"Time": true, "Value": true, "__name__": true, "cntlid": true, "container": true, "endpoint": true, "instance": true, "job": true, "namespace": true, "pod": true, "service": true, "domainname": true, "machine": true, "release": true, "sysname": true, "version": true, "state": true, "nvmedev": true},
             "indexByName": {},
-            "renameByName": {"nodename": "node", "device": "device", "model": "model", "serial": "serial", "firmware_revision": "firmware"}
+            "renameByName": {"nodename": "node", "device": "device", "model": "model", "serial": "serial", "firmware_revision": "firmware", "ceph_daemon": "ceph OSD"}
           }
         }
       ],
@@ -58,7 +140,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 9, "w": 12, "x": 0, "y": 9},
+      "gridPos": {"h": 9, "w": 12, "x": 0, "y": 13},
       "id": 2,
       "options": {"legend": {"calcs": ["mean", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
       "targets": [
@@ -91,7 +173,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 9, "w": 12, "x": 12, "y": 9},
+      "gridPos": {"h": 9, "w": 12, "x": 12, "y": 13},
       "id": 3,
       "options": {"legend": {"calcs": ["mean", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
       "targets": [
@@ -124,7 +206,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 9, "w": 12, "x": 0, "y": 18},
+      "gridPos": {"h": 9, "w": 12, "x": 0, "y": 22},
       "id": 4,
       "options": {"legend": {"calcs": ["mean", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
       "targets": [
@@ -162,7 +244,7 @@
           }
         ]
       },
-      "gridPos": {"h": 9, "w": 12, "x": 12, "y": 18},
+      "gridPos": {"h": 9, "w": 12, "x": 12, "y": 22},
       "id": 5,
       "options": {"legend": {"calcs": ["mean", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
       "targets": [
@@ -184,7 +266,7 @@
     },
     {
       "datasource": {"type": "prometheus", "uid": "prometheus"},
-      "description": "Composite temperature reported by each controller, read from hwmon in sysfs. This is the one health value available without an admin ioctl, which is why it is the only SMART-adjacent series on this dashboard.",
+      "description": "Composite temperature reported by each controller, read from hwmon in sysfs. This is the one health value available without an admin ioctl, which is why it is the only SMART-adjacent series on this dashboard. The thresholds are generic NVMe limits rather than any particular drive's rating — check the datasheet before treating a crossing as urgent.",
       "fieldConfig": {
         "defaults": {
           "color": {"mode": "palette-classic"},
@@ -195,7 +277,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 9, "w": 12, "x": 0, "y": 27},
+      "gridPos": {"h": 9, "w": 12, "x": 0, "y": 31},
       "id": 6,
       "options": {"legend": {"calcs": ["mean", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
       "targets": [
@@ -222,7 +304,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 9, "w": 12, "x": 12, "y": 27},
+      "gridPos": {"h": 9, "w": 12, "x": 12, "y": 31},
       "id": 7,
       "options": {"legend": {"calcs": ["mean", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
       "targets": [
@@ -244,11 +326,40 @@
     },
     {
       "datasource": {"type": "prometheus", "uid": "prometheus"},
-      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 36},
+      "description": "EPHEMERAL fill level per node. Growth here is usually container images and pod scratch space rather than anything Ceph does.",
+      "fieldConfig": {
+        "defaults": {
+          "color": {"mode": "palette-classic"},
+          "custom": {"axisCenteredZero": false, "axisColorMode": "text", "axisPlacement": "auto", "barAlignment": 0, "drawStyle": "line", "fillOpacity": 10, "gradientMode": "none", "hideFrom": {"legend": false, "tooltip": false, "viz": false}, "lineInterpolation": "smooth", "lineWidth": 2, "pointSize": 5, "scaleDistribution": {"type": "linear"}, "showPoints": "never", "spanNulls": false, "stacking": {"group": "A", "mode": "none"}, "thresholdsStyle": {"mode": "dashed"}},
+          "mappings": [],
+          "max": 1,
+          "min": 0,
+          "thresholds": {"mode": "absolute", "steps": [{"color": "green", "value": null}, {"color": "orange", "value": 0.7}, {"color": "red", "value": 0.85}]},
+          "unit": "percentunit"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 40},
+      "id": 9,
+      "options": {"legend": {"calcs": ["last", "max"], "displayMode": "table", "placement": "bottom", "showLegend": true}, "tooltip": {"mode": "multi", "sort": "desc"}},
+      "targets": [
+        {
+          "datasource": {"type": "prometheus", "uid": "prometheus"},
+          "expr": "(1 - node_filesystem_avail_bytes{mountpoint=\"/var\"} / node_filesystem_size_bytes{mountpoint=\"/var\"}) * on (instance) group_left(nodename) node_uname_info",
+          "legendFormat": "{{nodename}} /var",
+          "refId": "A"
+        }
+      ],
+      "title": "EPHEMERAL usage",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "gridPos": {"h": 11, "w": 24, "x": 0, "y": 48},
       "id": 8,
       "options": {
         "code": {"language": "plaintext", "showLineNumbers": false, "showMiniMap": false},
-        "content": "### What this dashboard cannot tell you\n\n**Endurance is missing.** There is no wear, no written-bytes total, no power-on hours and no media-error count here, because no exporter in this cluster produces them. NVMe reports those over an admin ioctl that needs elevated privileges, and temperature is the only health value the kernel publishes through sysfs. Tracked as **#549** — do not read a healthy dashboard as a healthy drive.\n\n**The three roles are not interchangeable.** Each node carries a Kingston OM8PGP41024Q as the Talos system disk, a Samsung PM983 that Rook claims as the Ceph OSD, and a Crucial P3 that was retired from Ceph and now carries the EPHEMERAL volume. The Crucial drives were replaced *because* they were worn, so the drive with the least endurance left is the one holding container state — and it is the one nothing is watching.\n\n**Device names are not identity.** `nvme0` is the Kingston on k8s-1 and k8s-3 and the Crucial on k8s-2. Every panel here resolves the model through `node_nvme_info` for that reason; a query written against a bare device name compares different hardware and will keep doing so silently.",
+        "content": "### What this dashboard cannot tell you\n\nThese notes are about mechanisms, not about the drives currently fitted. The inventory table above is the live answer to what is in the machines; nothing here restates it, because prose does not get re-read when hardware is swapped.\n\n**Endurance is missing.** No wear, no written-bytes total, no power-on hours, no media-error count — no exporter here produces them. NVMe reports those over an admin ioctl that needs elevated privileges; temperature is the only health value the kernel publishes through sysfs. Tracked as **#549**. Do not read a green top row as a healthy drive.\n\nCeph does record wear, but only inside its own devicehealth module and not in Prometheus: `kubectl -n rook-ceph exec deploy/rook-ceph-tools -- ceph device ls`. It covers OSDs and nothing else, and a drive removed from Ceph is purged from that registry — its history goes with it, so the wear figure of a retired drive is not recoverable after the fact.\n\n**Roles are assigned in configuration, not by device name.** Talos selects the system disk and the EPHEMERAL volume by serial, Rook selects the OSD by `/dev/disk/by-id` path. Two consequences outlive any particular set of drives: a broad selector such as `disk.transport == 'nvme'` matches every drive in the box, with the installer taking the OSD as the failure mode — and a drive retired from Ceph is not necessarily out of service, so the drive with the least endurance left can be the one carrying container state.\n\n**A dying NVMe here hangs rather than errors.** Talos boots with `nvme_core.io_timeout=4294967295`, so NVMe commands never time out. Expect a stall, not an I/O error, and expect the latency panel to go flat rather than spike.\n\n**Kernel messages are not retained.** Talos kernel logs do not reach Loki — the only log jobs are Kubernetes pods and a systemd-journal from elsewhere. `talosctl -n <node> dmesg` is the only source, it is a ring buffer, and a reboot empties it. An NVMe error from before the last reboot left no trace anywhere.",
         "mode": "markdown"
       },
       "title": "Gaps and caveats",