Configuration

Prometheus configuration

The Prometheus config file is at /etc/prometheus/prometheus.yml. It is pre-configured to scrape Node Exporter on localhost.

To add additional scrape targets, edit this file:

# /etc/prometheus/prometheus.yml
scrape_configs:
  - job_name: 'node'
    static_configs:
      - targets: ['localhost:9100']

  # Add your own targets:
  - job_name: 'my-app'
    static_configs:
      - targets: ['app-server-ip:8080']

After editing, reload Prometheus:

sudo systemctl reload prometheus
# or
curl -X POST http://localhost:9090/-/reload

Adding Grafana dashboards

1. Log in to Grafana at http://<ec2-ip>:3000
2. Go to Dashboards → Import
3. Enter a dashboard ID from grafana.com/grafana/dashboards

Popular dashboards:

• 1860 — Node Exporter Full
• 11074 — Node Exporter for Prometheus Dashboard
• 3662 — Prometheus 2.0 Stats

Grafana data source

Grafana is pre-configured with a Prometheus data source pointing to http://localhost:9090. You can verify or modify this at Configuration → Data Sources → Prometheus.

Alerting

To set up alerting rules in Prometheus, create rule files and reference them in prometheus.yml:

rule_files:
  - /etc/prometheus/rules/*.yml

Example alert rule:

# /etc/prometheus/rules/node-alerts.yml
groups:
  - name: node
    rules:
      - alert: HighCPU
        expr: 100 - (avg by(instance)(rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100) > 80
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High CPU usage on {{ $labels.instance }}"