What are Prometheus and Grafana?

Question

Accepted Answer

**Prometheus** — metrics collection.
**Grafana** — visualization.

```yaml
# prometheus.yml
global:
  scrape_interval: 15s

scrape_configs:
  - job_name: "node"
    static_configs:
      - targets: ["localhost:9100"]
  - job_name: "app"
    static_configs:
      - targets: ["localhost:8080"]
```

```promql
# PromQL queries
rate(http_requests_total[5m])  # Request rate
histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))  # P95
up == 0  # Down targets
```

**Components:**
- Prometheus — metrics collection and storage.
- AlertManager — alerting.
- Grafana — dashboards.
- Node Exporter — server metrics.

DevOps: What are Prometheus and Grafana?