Why not just use real user monitoring (RUM)?

Use both. RUM tells you what happened to real users; synthetics tell you what will happen next from controlled locations with zero sampling bias. Synthetics are your early-warning system and a safe canary gate.

Won’t synthetic tests be flaky and noisy?

Only if you treat them like afterthoughts. Keep the suite tiny, stabilize selectors, seed data, enforce strict timeouts, and page on burn rate across two windows. We delete or fix any synthetic that flakes twice without correlated impact.

Can I do this with Datadog/New Relic instead of Prometheus?

Yes. Datadog Synthetics and NR Synthetics ship browser checks and SLOs out of the box. The key is the same: emit leading indicators (p95/p99, success rate), define burn-rate alerts, and wire webhook/Argo integrations to gate rollouts.

Is Pushgateway safe for production signals?

It’s fine for low-frequency, short-lived jobs like synthetics if you treat it as an ingestion edge. Do not rely on it for high-cardinality or high-volume metrics. If you can, prefer native remote write (k6) or a lightweight sidecar that pushes OTLP to a collector.

How do I avoid false positives from regional blips?

Run from at least two regions and require both to violate the SLO before paging (route-level inhibition). Keep a ‘control’ synthetic that hits a static asset to distinguish app vs. network/CDN issues.

Reliability-observability · Oct 31, 2025 · 9 minute read

The Synthetic Checks That Saved Our Canary: Leading Indicators Wired to Argo Rollouts

Stop shipping blind. Build synthetic monitors that mirror real user journeys, surface leading indicators, and auto-drive canary decisions before customers ever feel it.

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The Synthetic Checks That Saved Our Canary: Leading Indicators Wired to Argo Rollouts

Key takeaways

Implementation checklist