my side project paged me at 3am on a work night — what is the minimum alerting that still lets me sleep

Two changes and my nights came back.

First, require consecutive failures. A single 60 second check firing on the first bad response is a blip detector, not an outage detector. Three consecutive failures means you find out about three minutes late and you stop hearing about every deploy, every certificate renewal, every provider hiccup. Nearly all of my noise was in that window.

Second, split the alert channels by what you would actually do. Down and staying down goes to push. Everything else — error rate up, queue backing up, disk at 80% — goes to an email that you read with coffee. If you would not get out of bed and open a laptop for it, it is not a page, it is a note.

Your real bug is the connection pool, and it will come back. Exhausted pools on a small box are almost always one of three things: a route that opens a connection per request and never returns it, a long-running job holding a transaction open, or your pool size multiplied by your process count being higher than the database will accept.

Put a connection pooler in front of the database, cap the pool per process, and set a statement timeout so a single stuck query cannot hold a slot forever. Then add a restart policy so the process dies and comes back instead of sitting there wedged. That one turns a page into a log line.

Nothing wakes me. Nothing. The app restarts itself on failure, there is a status page that updates automatically, and there is a digest at 08:00 with everything that happened. Two years of that and I have lost exactly one customer to overnight downtime, which is fewer than I lost to being visibly exhausted in customer calls.

Cheapest setup that works, in order of what I would add: an external uptime check with a multi-failure threshold, an auto-restart on the process, a static status page on a different host than the app, and error tracking with a daily digest rather than instant alerts. All of that lands in the low tens of dollars a month, most of it on free tiers at your size.

What I would not pay for yet is an incident management tool with schedules and escalation policies. You are the schedule. There is nobody to escalate to.

Separate thought: write the downtime expectation on your own site before someone asks. One line saying you aim for business-hours response and that overnight incidents are picked up in the morning. It costs you almost no customers at a small price point and it converts a 3am panic into a policy you already published.