Grafana

Dashboard JSON Gotchas

Required Fields

{
  "dashboard": {
    "id": null,           // null for new, existing ID for update
    "uid": "unique-id",   // Stable identifier for API/links
    "title": "Name",
    "panels": []
  },
  "overwrite": true       // Required at root level for updates
}

Panel Positioning

gridPos uses 24-column grid. Panels auto-stack if positions overlap.

"gridPos": {"h": 8, "w": 12, "x": 0, "y": 0}

Data Source Reference

Always use UID, not name (names can change):

"datasource": {"type": "prometheus", "uid": "prometheus-uid"}

Template Variable Syntax

Variable Query Refresh

• 0: Never (on dashboard load only)
• 1: On dashboard load
• 2: On time range change (use this for most cases)

Alerting (Grafana 9+)

Alert Rule Data Array

"data": [
  {"refId": "A", "model": {"expr": "..."}},           // Query
  {"refId": "B", "reducer": "last", "expression": "A"}, // Reduce
  {"refId": "C", "type": "threshold", "expression": "B", "conditions": [...]} // Condition (must be last)
]

The condition field in the rule must reference the final refId (here "C").

No Data / Error States

• NoData: Query returns empty
• Alerting: Treat no data as firing
• OK: Treat no data as resolved
• Error: Evaluation failed

Common Panel Configs

Thresholds

"thresholds": {
  "mode": "absolute",  // or "percentage"
  "steps": [
    {"color": "green", "value": null},  // null = base
    {"color": "yellow", "value": 70},
    {"color": "red", "value": 90}
  ]
}

Value Mappings

"mappings": [
  {"type": "value", "options": {"0": {"text": "Down", "color": "red"}}},
  {"type": "range", "options": {"from": 1, "to": 100, "result": {"text": "OK"}}}
]

Units

• percentunit: 0-1 displayed as 0%-100%
• percent: Already 0-100, displayed as-is
• bytes vs decbytes: Binary (1024) vs decimal (1000)
• s, ms, µs, ns: Auto-scales appropriately