A pod restarts every few minutes. The team digs through application logs looking for a crash that never happened, because the app did not crash. A probe killed it, on schedule, exactly as configured.

Probes are three small HTTP checks with outsized power. One of them can restart your containers, one controls whether traffic reaches them, and one decides how long they get to start up. Wire them up carelessly and Kubernetes will faithfully convert a small dependency hiccup into a fleet-wide restart storm. Wire them up well and most users never notice a bad deploy or a deadlocked process.

Three probes, three different jobs

Startup probe answers one question: has this container finished starting? While it is still failing, Kubernetes leaves the other probes alone and simply waits. Once it succeeds, it never runs again for that container.…