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fix(journal): reuse a dedicated pool for /api/health instead of per-call connect

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The previous handler opened a fresh postgres client (max: 1) on every
call to /api/health and tore it down in the finally block. Under the
prod monitoring cadence (probes every few seconds), that's a fresh
TCP + TLS + auth handshake on every probe, plus connection-table
churn on the Postgres side — fine for the trickle of curl-ish manual
checks, slow-bleed under blackbox monitoring.

Now we cache a module-level singleton postgres client dedicated to
/api/health (max: 2, idle_timeout: 30) and reuse it across calls.
Separate from the app's main DB pool (via @trails-cool/db's createDb)
on purpose — so a starvation event on the main pool doesn't fail the
liveness check and trigger a restart loop.

Full repo: pnpm typecheck, pnpm lint, pnpm test all green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Ullrich Schäfer 2026-05-24 12:37:09 +02:00
parent dfdb8b6daf
commit 8675c1f7c3
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1 changed files with 15 additions and 5 deletions
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20
apps/journal/server.ts
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@ -9,7 +9,7 @@ import { randomUUID } from "node:crypto";
import { httpRequestDuration, registry } from "./app/lib/metrics.server.ts";
import { createBoss, startWorker } from "@trails-cool/jobs";
import { getDatabaseUrl } from "@trails-cool/db";
import postgres from "postgres";
import postgres, { type Sql } from "postgres";
// Sentry DSN is read from env so self-hosted instances don't ship their
// errors to the trails.cool flagship Sentry by default. The flagship
@ -76,17 +76,27 @@ async function handleMetrics(_req: IncomingMessage, res: ServerResponse): Promis
const version = process.env.SENTRY_RELEASE ?? "dev";
// Module-level singleton postgres client dedicated to /api/health. The
// previous handler opened a fresh client + connection on every call,
// which OOM'd the process under monitoring load (probes hit /api/health
// every few seconds). `max: 2` is plenty for liveness checks; the main
// app DB pool is separate (via @trails-cool/db's createDb).
let healthClient: Sql | null = null;
function getHealthClient(): Sql {
if (!healthClient) {
healthClient = postgres(getDatabaseUrl(), { max: 2, idle_timeout: 30 });
}
return healthClient;
}
async function handleHealth(_req: IncomingMessage, res: ServerResponse): Promise<void> {
const client = postgres(getDatabaseUrl(), { max: 1 });
try {
await client`SELECT 1`;
await getHealthClient()`SELECT 1`;
res.writeHead(200, { "Content-Type": "application/json" });
res.end(JSON.stringify({ status: "ok", version, db: "connected" }));
} catch {
res.writeHead(503, { "Content-Type": "application/json" });
res.end(JSON.stringify({ status: "degraded", version, db: "unreachable" }));
} finally {
await client.end();
}
}