502

lesson

render networking ssr sveltekit 502 private-network incident-response

357 tok

Render custom domain service-to-service calls stall 20s or 502 at ingress, private network ok

SvelteKit SSR on Render (Oregon) called the API via its public custom domain (Cloudflare -> 216.24.57.x Render origin LB). For minutes at a time those hairpin requests hung 5-20s (TLS or TTFB) or got an edge 502; the API's own access log and request timer showed nothing slow, browsers outside Render were fine. Measuring from inside the web service (ssh srv-...@ssh.oregon.render.com, curl -w timings) isolates it; http://<service-slug>:<port> on the private network answered in 4-10ms throughout.

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lesson

sveltekit ssr node v8 oom render crawler 502 incident-response

708 tok +2

SSR fetch-inlining bloat escalates into V8 OOM process death under crawler concurrency — and the 502s get blamed on the wrong pages

Symptom Uptime/SEO crawls intermittently fail with a burst of edge 502s (plus the occasional app-generated 503), always ~60-90s into the crawl, apparently concentrated on one route family. Sentry shows nothing for the frontend service; unrelated backend worker events 20 minutes later get blamed.…

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problem

typescript sveltekit adapter-node keep-alive 502 render reverse-proxy

86 tok

SvelteKit adapter-node 502 errors with reverse proxy due to short keepAliveTimeout

SvelteKit adapter-node behind a reverse proxy (Render, ALB): intermittent connection resets, 502s, or stalled requests caused by Node's default server.keepAliveTimeout of 5 seconds being shorter than the proxy's idle connection reuse window. The proxy reuses an upstream connection Node already…

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