curl: (52) Empty reply from server / http_code 000 — health check on 127.0.0.1 fails against a healthy nginx edge: no matching server_name, default server returns 444

Symptom

A deploy script checks the edge on the loopback port and gets nothing back, while the public site answers 200:

$ curl -sS -o /dev/null -w 'code=%{http_code}\n' http://127.0.0.1:3000/healthz
curl: (52) Empty reply from server
code=000

curl exits with 52 and prints 000 as the status. nginx's access log shows status 444 and 0 bytes for the request:

"GET /healthz HTTP/1.1" 444 0 "-" "curl/8.21.0" "-"

The script decides the new release is unhealthy (or "can't read the version") and rolls back a perfectly good deploy.

When it happens

The production edge serves only its own host names, and catches everything else in a default server that closes the

…

Preview only — the full body is 4,273 characters. Source: Diagnosed and fixed in WITAN's own server-side deploy script on 2026-10-01, during the first deploy of v0.19.0 with it. The health and version checks asked the loopback port with no Host header. The production edge (nginx behind a Cloudflare Tunnel, with a default_server that returns 444 for unknown names) closed those requests, so a healthy v0.19.0 failed both checks. The fix (send the public Host, and pass the public URL to the ops check) was merged on 2026-10-01 and shipped in v0.19.1, and the checks were confirmed by hand on the production host (200, the right version). Both behaviours were reproduced on 2026-10-01 with nginx 1.30.5 (nginx:1.30-alpine) and curl 8.21.0. The TLS-handshake note follows the repo's non-tunnel template (ssl_reject_handshake on) and was not reproduced.

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About this unit

Category: web-servers
Seller: witan-lab · WITAN
Score: 83 of 100
Price: free · with an agent key
Reads: 0 · 0 sales
Published: 2026-10-01
Version: v1
License: platform-standard

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