Observability for QA — Logs, Metrics, Traces (2026)
QA is not just pre-prod anymore. Learn how to instrument tests with OpenTelemetry, read distributed traces, and use production observability to find bugs users have not reported yet.
Last updated 2026-07-20 · 11 min read · By Avinash K
Shift-right is where the next 10 years of QA lives. Instead of only guarding merges, QA teams read production traces, catch anomalies before customers do, and instrument their own tests to produce first-class telemetry. This guide gets you literate in the 3 pillars — logs, metrics, traces — and shows the OpenTelemetry setup we ship on client projects.
Key takeaways
- The 3 pillars — logs, metrics, traces.
- OpenTelemetry from a Playwright test.
- Reading a distributed trace to root-cause a bug.
- Anomaly alerts QA should own.
1. The 3 pillars
| Pillar | Answers | Tool examples |
|---|---|---|
| Logs | What happened? | Loki, Datadog, Elasticsearch |
| Metrics | How much / how often? | Prometheus, Datadog |
| Traces | Where did the time go? | Jaeger, Tempo, Honeycomb |
2. OpenTelemetry from Playwright
import { trace } from '@opentelemetry/api';
const tracer = trace.getTracer('e2e-tests');
test('checkout flow', async ({ page }) => {
await tracer.startActiveSpan('checkout', async (span) => {
span.setAttribute('test.suite', 'smoke');
await page.goto('/');
// ... test steps
span.end();
});
});Every E2E run now shows up in your trace backend alongside prod traffic — you can see if a test slowed down because your code did.
3. Reading a distributed trace
A trace shows the request path across services: frontend → API gateway → auth → orders → DB. Look for: (a) the longest span (bottleneck), (b) error spans (red), (c) missing spans (gap = untraced service). That is 90% of root-causing.
4. Alerts QA should own
- Error rate spike per endpoint (>2x 7-day p99).
- Latency regression per endpoint (>30% p95 vs last week).
- Failed login rate (spam or auth outage).
- Checkout funnel drop-off (business metric).
Related: shift-left playbook, k6 tutorial, CI/CD for QA. Docs: opentelemetry.io/docs.