Grafana

Grafana is a data visualization and monitoring tool. It connects to various data sources (like Prometheus, InfluxDB, MySQL, etc.) and allows one to create dashboards, graphs, and alerts to monitor metrics in real time.

Here is a quick example with grafana + prometheus + node exporter on localhost (macos).

Component	Port	Purpose
Node Exporter	9100	Exposes system metrics (CPU, memory, disk, etc.)
Prometheus	9090	Collects metrics and stores them
Grafana	3000	Visualizes metrics in dashboards

Assuming Node Exporter and Prometheus are already running.

brew install grafana
brew services start grafana

Open browser(admin/admin): http://localhost:3000/login

Go to Settings → Data Sources → Add data source → Prometheus. Then add http://localhost:9090.

To add node exporter; go to Dashboards, then import the dashboard using this ID: 1860. This will import a pre-built dashboard for node exporter.

To stress cpu and see changes in the dashboard:

brew install stress
stress --cpu 4 --timeout 60

Alternatively, one can import dashboards:

cpu

{
  "id": null,
  "title": "CPU Utilization",
  "tags": [
    "example"
  ],
  "timezone": "browser",
  "schemaVersion": 39,
  "version": 1,
  "refresh": "5s",
  "panels": [
    {
      "type": "timeseries",
      "title": "CPU Utilization (%)",
      "datasource": {
        "type": "prometheus",
        "uid": "prometheus"
      },
      "targets": [
        {
          "expr": "100 * (1 - avg(rate(node_cpu_seconds_total{mode=\"idle\"}[2m])))",
          "legendFormat": "CPU Utilization",
          "refId": "A"
        }
      ],
      "fieldConfig": {
        "defaults": {
          "unit": "percent",
          "min": 0,
          "max": 100
        },
        "overrides": []
      },
      "gridPos": {
        "x": 0,
        "y": 0,
        "w": 24,
        "h": 9
      }
    }
  ]
}

cpuanddisk

{
  "id": null,
  "title": "CPU and Disk Usage",
  "tags": [
    "example"
  ],
  "timezone": "browser",
  "schemaVersion": 39,
  "version": 1,
  "refresh": "5s",
  "panels": [
    {
      "type": "timeseries",
      "title": "CPU Utilization (%)",
      "datasource": {
        "type": "prometheus",
        "uid": "prometheus"
      },
      "targets": [
        {
          "expr": "100 * (1 - avg(rate(node_cpu_seconds_total{mode=\"idle\"}[2m])))",
          "legendFormat": "CPU Utilization",
          "refId": "A"
        }
      ],
      "fieldConfig": {
        "defaults": {
          "unit": "percent",
          "min": 0,
          "max": 100
        },
        "overrides": []
      },
      "gridPos": {
        "x": 0,
        "y": 0,
        "w": 24,
        "h": 9
      }
    },
    {
      "type": "timeseries",
      "title": "Disk Usage (%)",
      "datasource": {
        "type": "prometheus",
        "uid": "prometheus"
      },
      "targets": [
        {
          "expr": "100 - (100 * (node_filesystem_avail_bytes{fstype!=\"tmpfs\",mountpoint!=\"/boot\"} / node_filesystem_size_bytes{fstype!=\"tmpfs\",mountpoint!=\"/boot\"}))",
          "legendFormat": "{{mountpoint}}",
          "refId": "B"
        }
      ],
      "fieldConfig": {
        "defaults": {
          "unit": "percent",
          "min": 0,
          "max": 100
        },
        "overrides": []
      },
      "gridPos": {
        "x": 0,
        "y": 9,
        "w": 24,
        "h": 9
      }
    }
  ]
}