Add Active alerts panel to the top of the CNX DNS dashboard

Surfaces vmalert's firing ALERTS series as a table at the top of the dashboard,
so the minimal-delivery alerts are visible at a glance. Existing panels shift
down by one row.

modules/monitoring/dashboards/dns.json

@@ -4,17 +4,58 @@
   "tags": ["dns", "knot", "cnx"],
   "timezone": "browser",
   "schemaVersion": 39,
-  "version": 1,
+  "version": 2,
   "refresh": "30s",
   "time": { "from": "now-6h", "to": "now" },
   "templating": { "list": [] },
   "annotations": { "list": [] },
   "panels": [
+    {
+      "type": "row",
+      "title": "Alerts",
+      "id": 11,
+      "gridPos": { "h": 1, "w": 24, "x": 0, "y": 0 }
+    },
+    {
+      "type": "table",
+      "title": "Active alerts",
+      "description": "Firing vmalert alerts (the ALERTS series vmalert writes back to VictoriaMetrics). An empty table means all clear.",
+      "id": 12,
+      "datasource": { "type": "prometheus", "uid": "victoriametrics" },
+      "gridPos": { "h": 7, "w": 24, "x": 0, "y": 1 },
+      "options": { "showHeader": true },
+      "fieldConfig": {
+        "defaults": { "custom": { "align": "auto" } },
+        "overrides": []
+      },
+      "targets": [
+        {
+          "refId": "A",
+          "datasource": { "type": "prometheus", "uid": "victoriametrics" },
+          "expr": "ALERTS{alertstate=\"firing\"}",
+          "format": "table",
+          "instant": true
+        }
+      ],
+      "transformations": [
+        {
+          "id": "organize",
+          "options": {
+            "excludeByName": {
+              "Time": true,
+              "Value": true,
+              "__name__": true,
+              "alertstate": true
+            }
+          }
+        }
+      ]
+    },
     {
       "type": "row",
       "title": "DNS / Zones",
       "id": 1,
-      "gridPos": { "h": 1, "w": 24, "x": 0, "y": 0 }
+      "gridPos": { "h": 1, "w": 24, "x": 0, "y": 8 }
     },
     {
       "type": "table",
@@ -22,7 +63,7 @@
       "description": "ns1 and ns2 should report the same serial per zone. A divergence here is the secondary-out-of-sync condition.",
       "id": 2,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 1 },
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 9 },
       "options": { "showHeader": true },
       "fieldConfig": {
         "defaults": { "custom": { "align": "auto" } },
@@ -45,7 +86,7 @@
       "description": "On secondaries this counts down between successful transfers; a steady decline toward zero means transfers are failing.",
       "id": 3,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 1 },
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 9 },
       "fieldConfig": { "defaults": { "unit": "s" }, "overrides": [] },
       "targets": [
         {
@@ -61,7 +102,7 @@
       "title": "Query rate by nameserver",
       "id": 4,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 9 },
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 17 },
       "fieldConfig": { "defaults": { "unit": "qps" }, "overrides": [] },
       "targets": [
         {
@@ -77,7 +118,7 @@
       "title": "Response codes",
       "id": 5,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 9 },
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 17 },
       "fieldConfig": { "defaults": { "unit": "qps" }, "overrides": [] },
       "targets": [
         {
@@ -92,14 +133,14 @@
       "type": "row",
       "title": "Hosts",
       "id": 6,
-      "gridPos": { "h": 1, "w": 24, "x": 0, "y": 17 }
+      "gridPos": { "h": 1, "w": 24, "x": 0, "y": 25 }
     },
     {
       "type": "timeseries",
       "title": "CPU busy %",
       "id": 7,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 18 },
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 26 },
       "fieldConfig": {
         "defaults": { "unit": "percent", "min": 0, "max": 100 },
         "overrides": []
@@ -118,7 +159,7 @@
       "title": "Memory used %",
       "id": 8,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 18 },
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 26 },
       "fieldConfig": {
         "defaults": { "unit": "percent", "min": 0, "max": 100 },
         "overrides": []
@@ -137,7 +178,7 @@
       "title": "Root filesystem used %",
       "id": 9,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 26 },
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 34 },
       "fieldConfig": {
         "defaults": { "unit": "percent", "min": 0, "max": 100 },
         "overrides": []
@@ -156,7 +197,7 @@
       "title": "Load average (1m)",
       "id": 10,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
-      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 26 },
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 34 },
       "fieldConfig": { "defaults": { "unit": "short" }, "overrides": [] },
       "targets": [
         {