Kill switch for noisy uptime checks: a feature flag to disable a polling client

Use a kill switch inside the checker when your uptime probes start amplifying an incident — one feature flag, read on every tick, that can disable the noisy checks and stop the retries at the source. Reach for tuned backoff and jitter instead when the retry storm stays inside a single process and never fans out onto a dependency somebody else is paging for. Both are cheap to build. Only one of them lets you quiet a polling client while its target is already on fire. I run cron and queue infrastructure, so most of my pages arrive as either "the job didn't run" or "the job ran four times." Health checking sits in the same family of problems: a small, frequent, automated request that multiplies badly when something upstream changes shape. What follows is the runbook I settled on after a fleet of pollers turned a non-incident into a real one — the failure mode, where the switch belongs, the implementation, and how to verify the flip before you walk away from the terminal. What actually turns a polling client's uptime checks into a retry storm? Amplification. A single check is one request every 15 or 30 seconds, which nobody notices; a fleet of checks with retries layered on top is a synchronized load generator pointed at whatever you decided was important enough to monitor. The math is unkind. Take 40 instances, a 5s interval, and 3 retries per failed attempt, and a dependency that normally handles a trickle of health traffic suddenly sees a couple thousand requests a minute — all of them arriving at the exact moment it's least able to absorb them. Retries stack on top of the polling interval rather than replacing it, and because every poller sees the same failure at the same time, they all back off together and return together. The Google SRE book calls out this shape under cascading failures, and the load pattern that comes out of it looks nothing like organic traffic: sawtooth spikes, perfectly aligned, growing until something sheds load. The worst one I've dealt wit