Discard Caddy's own diagnostics in front of the relay

[frahlg]

Problem

Caddy's global log on the relay host goes to /var/log/caddy/caddy.log at ERROR level with no filter (relay/deploy/Caddyfile). Two kinds of record end up there:

• A proxy error names the request URI, which carries the rendezvous handle, next to the client address.
• Go's "TLS handshake error from " puts the address in the message text itself. A field filter cannot reach it.

The iOS App Store work (srcfl/ftw-app#13) found this while it filled in the App Privacy answers. With this log, the honest answer would have to declare "Other Diagnostic Data". Fredrik chose to remove the addresses instead.

Change

• The global log block now uses output discard, as escrow/deploy/Caddyfile already does and for the same reason. A filter only covers the fields somebody thought of.
• The site access log stays. Its filter already deletes request>uri, request>headers, request>remote_ip and request>client_ip.
• relay/deploy/caddyfile.test.ts is new and holds both rules:
  • exactly two log blocks;
  • the global block discards;
  • the access log deletes the four fields;
  • no log goes to stdout or stderr.
• A changeset is included.

Cost: there is no Caddy log to read when a certificate stops renewing. An outside curl -sI https://relay.ftw.energy/healthz covers that.

Evidence

• The new test fails against the old Caddyfile (discards Caddy's own diagnostics) and passes against the new one.
• npm run verify: 105 files passed and 1 skipped; 1062 tests passed and 1 skipped; svelte-check reports 0 errors; the build passed.
• Not run: Caddy itself. No local Caddy binary was available. Validate it on the host before you reload.

After merge (operator, on the relay host)

1. Deploy as usual, then run docker compose exec caddy caddy validate --config /etc/caddy/Caddyfile.
2. Remove the old diagnostics, which may hold addresses and handles: docker compose exec caddy sh -c 'rm -f /var/log/caddy/caddy.log*'.
3. Check from outside: curl -sI https://relay.ftw.energy/healthz.

🤖 Generated with Claude Code

[chatgpt-codex-connector]

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-12T17:18:56.292948Z	7cc2f0e	PR opened

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[chatgpt-codex-connector]

Use GET for the external health check

When an operator adopts this command as the replacement for the discarded diagnostics, it never receives the health endpoint's successful response: curl --manual documents that HTTP -I uses HEAD, while RelayServer.start() accepts /healthz only when req.method === 'GET' and otherwise returns 426. This can produce a permanent false failure in monitoring; use the GET command already documented in relay/deploy/README.md or add HEAD handling to the endpoint.

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