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A bucket is where exports, dumps and warehouse feeds land, and a bucket is very good at looking the same on the morning nothing was written to it. Point us at one prefix, and if the day’s object is not there on time, you hear about it.
One prefix per monitor. "New" means an object that was not under that prefix on the last look, and a name pattern narrows it further when several senders share a bucket.
We list, and we read what a listing carries: key, size and last-modified. Nothing fetches an object.
The bucket, the region, and the prefix to watch.
A key that can list that prefix and nothing else. It goes into the vault once, and after saving the field becomes a Replace button.
Healthy - A new object appeared under the prefix inside the window, or the window has not opened yet.
Missed - The listing never showed a new object before grace ran out.
Check broken - The key was revoked or rotated, or the policy no longer allows the listing. That is its own alert, never a miss.
Four steps, and one test that has to pass before anything is saved.
Common questions: A prefix that receives several files a day works: each schedule is its own monitor. Nothing else in the bucket is reachable with a key scoped to one prefix, which is the shape we ask for.
Free for 3 monitors. The test has to pass before anything is saved.