Four conditions gate every emergency container this watchdog is allowed to start

live-app-watchdog.sh is allowed to start an emergency container only when four things are true at once. No healthy backend is serving the domain, no deployment or maintenance window is active, the locally retained image has been verified by digest and configuration, and an exclusive lock is held so two watchdog runs cannot start two bridges ^[10]. The lock came out of an incident. Two overlapping runs each decided the app was down, each started a container, and the proxy had two backends running different code ^[11]. "The lock is one line. It is the most important line in the file," the post says ^[12]. That condition travels only as far as the lock's scope, and two watchdog processes on one box are a different problem from two hosts that can each serve the same domain.

post-deploy-repair-loop.sh is the tightest of the three at 187 lines because it fires immediately after every deployment, and a bad pattern there would spread across thirteen apps before lunch ^[13]. It runs an HTTP check, then a visual check on whether the rendered page looks right and not only whether it returned 200. Then a fix from a short list of known remediations, then the checks again, three iterations at most ^[14]. The ceiling is in the file as max_attempts=3 ^[15]. When the budget is spent the script stops, marks the incident open and wakes a human after the third attempt ^[7]. The alternative the post documents is a well-meant loop that restarted the same container forty times while the actual cause was a full disk ^[6].

The two named scripts account for 476 lines of the just-over-a-thousand-line total, which leaves roughly 530 for the third; the excerpt breaks off before naming it ^[1]. The spike the monitoring loop caught was a load average of 33.59 against a normal of about four, roughly eight times normal ^[4][2].

For the 01:00 all-green to mean anything on someone else's box, a few things have to hold. Deployments have to leave a window state the watchdog can read, and images have to be retained locally and checkable by digest, or the script cannot safely start anything ^[10]. Half an hour of degradation has to be acceptable for whatever is degraded ^[3]. The author reads the incident at breakfast, and the entry sits in an operations journal, timestamped, with the load numbers and the action taken ^[16].

The prediction the post opens with is one operator's expectation: in three weeks most of the new installs will be a process on a box nobody watches, failing in a way nobody notices until a customer or a cron job does ^[17]. The recovery record behind it is a single journal entry from one night on the two servers he runs ^[4][2].