webgrind/docker/grafana/dashboard.json

{
    "title": "Loki",
    "panels": [
      {
        "title": "Error Rate",
        "type": "graph",
        "datasource": "Loki", 
        "targets": [
          {
            "expr": 'sum(rate({job="my-app", level="error"}[1m])) by (level)',
            "legendFormat": "{{level}}",
            "refId": "A" 
          }
        ]
      }
    ]
  }