Verifying against reality.
WHY IT IS NECESSARY
No environment reproduces production entirely.
WHAT IT INCLUDES
Monitoring and alerting Synthetic transactions Gradual rollout Feature flags Comparison of old and new behaviour
WHAT SYNTHETIC MONITORING IS
Automated journeys run continuously against production.
WHAT IT CATCHES
Failures affecting real users, before they report them.
WHAT TO MONITOR SYNTHETICALLY
Sign-in The primary workflow Payment, where applicable
WHAT FEATURE FLAGS PROVIDE
Enabling changes for a subset, and disabling instantly.
WHY THAT MATTERS
Recovery in seconds rather than a release cycle.
WHAT CANARY RELEASE MEANS
Sending a small proportion of traffic to the new version.
WHAT TO COMPARE
Error rates, latency, and business outcomes between versions.
WHAT SHADOW TRAFFIC IS
Sending real requests to a new version without using its responses.
WHAT IT PROVIDES
Real-world verification with no risk.
WHAT TO BE CAREFUL WITH
Side effects from shadowed requests Test data entering production systems Synthetic transactions distorting analytics
WHAT TO MARK
Synthetic activity, so it can be excluded.
WHAT TO ALWAYS HAVE
A rollback path that works.
