What types of metrics does Prometheus have?

Question

Accepted Answer

**4 types:**

**1. Counter** — only increases:
```promql
http_requests_total{method="GET", status="200"}
rate(http_requests_total[5m])
increase(http_requests_total[1h])
```

**2. Gauge** — current value:
```promql
node_memory_MemAvailable_bytes
node_filesystem_avail_bytes
up
```

**3. Histogram** — distribution by buckets:
```promql
histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))
histogram_quantile(0.99, rate(http_request_duration_seconds_bucket[5m]))
sum(rate(http_request_duration_seconds_sum[5m])) /
sum(rate(http_request_duration_seconds_count[5m]))
```

**4. Summary** — client-side percentile:
```promql
http_request_duration_seconds{quantile="0.95"}
```

**Histogram vs Summary:** Histogram can be aggregated (recommended). Summary cannot.

DevOps: What types of metrics does Prometheus have?