What is a synthetic / black-box check, and what would you monitor with one? [Intermediate]
Answer
A synthetic or black-box check is an automated external probe that simulates a user or client action. I use it for critical user journeys, public endpoints, DNS/TLS validity, login, checkout, and dependency reachability.
Technical explanation
Synthetic checks validate the full path, including network, gateway, routing, certificate, and application availability.
They should be simple enough to be reliable and scoped enough to avoid creating fake business transactions incorrectly.
For complex flows, use test accounts and cleanup logic.
Hands-on example
Hands-on: deploy blackbox_exporter and configure an HTTP probe for /health, a TLS probe for certificate expiry, and a scripted synthetic for login -> add item -> checkout preview. Alert if probes fail from two regions for more than five minutes.
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