Skip to content
Watasu Docs

Metrics

The metrics add-on scrapes Prometheus-style metrics from your app and surfaces them in Grafana, alongside platform metrics that Watasu reports for you.

Attach it

Section titled “Attach it”
Terminal window
watasu addons:create metrics --app my-app

If this is your first observability add-on, Grafana is provisioned automatically.

What gets collected

Section titled “What gets collected”

Two streams flow into Grafana:

Your app’s metrics — anything your processes expose on a Prometheus-compatible endpoint. Use any standard client library (prometheus_client in Python, prom-client in Node, prometheus-client for Ruby/Rails, etc.). Watasu scrapes them on a regular interval.

Platform metrics — Watasu publishes runtime data without you instrumenting it:

  • pod CPU and memory usage
  • pod restarts and OOMKilled events
  • attached add-on metrics (PostgreSQL, Valkey, object storage, and so on)

You get both in the same Grafana, ready to query.

Best-effort scraping

Section titled “Best-effort scraping”

If a process doesn’t expose metrics, or exposes them on a different port, Watasu skips it gracefully. Metrics collection failing never blocks an app from running.

What to instrument first

Section titled “What to instrument first”

Don’t try to instrument everything on day one. The high-leverage metrics for most apps:

  • request latency (histogram, p50/p95/p99)
  • request rate by endpoint
  • error rate (HTTP 5xx, exceptions)
  • queue depth or job latency for workers
  • one or two domain-specific business metrics (“orders per minute”, “active sessions”)

Wider coverage can come later. Five well-named, well-shaped metrics beat fifty noisy ones.

Cardinality discipline

Section titled “Cardinality discipline”

Every unique combination of labels is a separate time series. High-cardinality labels (user IDs, request IDs, full URLs) explode storage and query cost. Stick to low-cardinality dimensions: status code, method, route name, queue name, region.

Alerts

Section titled “Alerts”

Grafana’s alerting UI lets you build alerts on top of any metric query. Hook them up to whatever paging or notification system your team already uses.

Set alerts on operational thresholds people will actually act on. Alerts that fire and get ignored train the team to ignore alerts.