fix(grafana): correct metric names in fabric-overview dashboard

Changed from:
- gnmic_interfaces_interface_state_counters_* with target label

To:
- gnmic_interfaces_* with source label

Also added:
- Interfaces Monitored stat panel
- MLAG Peer-Link Traffic panel

These match the actual metrics generated by gNMIc.

monitoring/grafana/dashboards/fabric-overview.json

@@ -16,17 +16,27 @@
       "gridPos": {"h": 4, "w": 6, "x": 0, "y": 3},
       "id": 2,
       "options": {"colorMode": "background", "graphMode": "none", "justifyMode": "center", "orientation": "auto", "reduceOptions": {"calcs": ["lastNotNull"], "fields": "", "values": false}, "textMode": "auto"},
-      "targets": [{"expr": "count(up{job=\"gnmic\"} == 1)", "legendFormat": "Devices", "refId": "A"}],
+      "targets": [{"expr": "count(count by (source) (gnmic_interfaces_in_pkts))", "legendFormat": "Devices", "refId": "A"}],
       "title": "Devices Online",
       "type": "stat"
     },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "fieldConfig": {"defaults": {"mappings": [], "thresholds": {"mode": "absolute", "steps": [{"color": "green", "value": null}]}, "unit": "short"}},
+      "gridPos": {"h": 4, "w": 6, "x": 6, "y": 3},
+      "id": 6,
+      "options": {"colorMode": "background", "graphMode": "none", "justifyMode": "center", "orientation": "auto", "reduceOptions": {"calcs": ["lastNotNull"], "fields": "", "values": false}, "textMode": "auto"},
+      "targets": [{"expr": "count(count by (source, interface_name) (gnmic_interfaces_in_pkts{interface_name=~\"Ethernet.*\"}))", "legendFormat": "Interfaces", "refId": "A"}],
+      "title": "Interfaces Monitored",
+      "type": "stat"
+    },
     {
       "datasource": {"type": "prometheus", "uid": "prometheus"},
       "fieldConfig": {"defaults": {"color": {"mode": "palette-classic"}, "custom": {"axisLabel": "bps", "drawStyle": "line", "fillOpacity": 20, "lineWidth": 2, "showPoints": "never"}, "unit": "bps"}},
       "gridPos": {"h": 8, "w": 12, "x": 0, "y": 7},
       "id": 3,
       "options": {"legend": {"displayMode": "table", "placement": "right", "showLegend": true}, "tooltip": {"mode": "multi"}},
-      "targets": [{"expr": "rate(gnmic_interfaces_interface_state_counters_in_octets{target=~\"spine.*\"}[1m]) * 8", "legendFormat": "{{target}} {{interface_name}}", "refId": "A"}],
+      "targets": [{"expr": "rate(gnmic_interfaces_in_octets{source=~\"spine.*\"}[1m]) * 8", "legendFormat": "{{source}} {{interface_name}}", "refId": "A"}],
       "title": "Spine Interface Traffic (Ingress)",
       "type": "timeseries"
     },
@@ -36,7 +46,7 @@
       "gridPos": {"h": 8, "w": 12, "x": 12, "y": 7},
       "id": 4,
       "options": {"legend": {"displayMode": "table", "placement": "right", "showLegend": true}, "tooltip": {"mode": "multi"}},
-      "targets": [{"expr": "rate(gnmic_interfaces_interface_state_counters_out_octets{target=~\"spine.*\"}[1m]) * 8", "legendFormat": "{{target}} {{interface_name}}", "refId": "A"}],
+      "targets": [{"expr": "rate(gnmic_interfaces_out_octets{source=~\"spine.*\"}[1m]) * 8", "legendFormat": "{{source}} {{interface_name}}", "refId": "A"}],
       "title": "Spine Interface Traffic (Egress)",
       "type": "timeseries"
     },
@@ -46,9 +56,19 @@
       "gridPos": {"h": 8, "w": 24, "x": 0, "y": 15},
       "id": 5,
       "options": {"legend": {"displayMode": "table", "placement": "right", "showLegend": true}, "tooltip": {"mode": "multi"}},
-      "targets": [{"expr": "rate(gnmic_interfaces_interface_state_counters_in_octets{target=~\"leaf.*\", interface_name=~\"Ethernet1[12]\"}[1m]) * 8", "legendFormat": "{{target}} {{interface_name}} IN", "refId": "A"}],
+      "targets": [{"expr": "rate(gnmic_interfaces_in_octets{source=~\"leaf.*\", interface_name=~\"Ethernet1[12]\"}[1m]) * 8", "legendFormat": "{{source}} {{interface_name}} IN", "refId": "A"}],
       "title": "Leaf Uplinks to Spines",
       "type": "timeseries"
+    },
+    {
+      "datasource": {"type": "prometheus", "uid": "prometheus"},
+      "fieldConfig": {"defaults": {"color": {"mode": "palette-classic"}, "custom": {"axisLabel": "bps", "drawStyle": "line", "fillOpacity": 20, "lineWidth": 2, "showPoints": "never"}, "unit": "bps"}},
+      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 23},
+      "id": 7,
+      "options": {"legend": {"displayMode": "table", "placement": "right", "showLegend": true}, "tooltip": {"mode": "multi"}},
+      "targets": [{"expr": "rate(gnmic_interfaces_in_octets{source=~\"leaf.*\", interface_name=\"Ethernet10\"}[1m]) * 8", "legendFormat": "{{source}} MLAG Peer-Link IN", "refId": "A"}],
+      "title": "MLAG Peer-Link Traffic",
+      "type": "timeseries"
     }
   ],
   "refresh": "10s",