Files
reverse-proxy/docs/architecture/README.md
glm-5.1 0d54eba41e Update architecture specs to reflect live deployment findings and fix two bugs
Architecture updates based on gaps discovered during live deployment testing:

- ADR-023: HTTP/2 client-facing support via ALPN-based protocol detection.
  The spec previously said HTTP/2 was out of scope, but the deployment
  revealed that modern browsers negotiate HTTP/2 via ALPN. The proxy now
  correctly detects the negotiated ALPN protocol and uses the appropriate
  HTTP server builder (http2::Builder for h2, auto::Builder for http/1.1).
  Upstream connections remain HTTP/1.1. Host resolution now falls back to
  URI host for HTTP/2 :authority pseudo-headers.

- ADR-024: ANSI-disabled logging. All tracing-subscriber layers now use
  with_ansi(false) to prevent ANSI escape codes in log output, which broke
  fail2ban regex matching in Docker deployments. Also documents the fail2ban
  regex anchor fix (^RATE_LIMIT → RATE_LIMIT).

Bug fixes found by architecture review:

- Fix missing ALPN protocols in manual TLS mode. build_manual_server_config
  and build_multi_domain_server_config did not set alpn_protocols, meaning
  manual TLS mode could not support HTTP/2. Added h2 and http/1.1 ALPN
  entries to both functions (acme-tls/1 only in ACME mode).

- Fix missing with_ansi(false) in JSON log format. The init_json function
  with file output did not disable ANSI on stdout or file layers, which would
  break fail2ban in production JSON logging mode.

Other spec updates:

- All document statuses updated from draft to reviewed
- proxy.md: documented Server header removal, upstream HTTPS client,
  two-phase timeout enforcement, HTTP/2 host resolution, connect timeout
- tls.md: documented ALPN configuration differing by mode (ACME vs manual)
- overview.md: added HTTP/2 client-facing support to scope, updated crate
  deps (hyper-rustls, rustls-native-certs, hyper-util), clarified out-of-scope
- config.md: fixed http_port type (u16→u32) to match implementation, added
  ANSI-disabled note for LoggingConfig
- operations.md: documented ANSI-disabled logging, fail2ban regex anchor
- open-questions.md: updated OQ-09 resolution (connect timeout fully
  implemented), OQ-10 (C2 bug is fixed)
2026-06-12 11:28:31 +00:00

5.8 KiB

status, last_updated
status last_updated
reviewed 2026-06-12

Reverse Proxy — Architecture

Current State

Phase 1 (Implementation) — Complete. The proxy is deployed and running in a Docker container, replacing our vulnerable nginx 1.24.0 installation.

This project replaces our vulnerable nginx 1.24.0 installation with a memory-safe Rust/axum reverse proxy. The primary motivation is CVE-2026-42945 (unauthenticated RCE in nginx's rewrite module) and the broader pattern of memory corruption bugs in nginx's C codebase.

The proxy supports multiple domains from initial release (git.alk.dev and alk.dev), with per-domain host-based routing and a single multi-domain SAN certificate via ACME. HTTP/2 is supported on the client-facing side (between the client and the proxy) with ALPN-based protocol detection. Upstream connections remain HTTP/1.1.

Architecture Documents

Document Status Description
overview.md Reviewed Vision, scope, crate dependencies, exports
proxy.md Reviewed Reverse proxy handler, request flow, header injection
tls.md Reviewed TLS termination, ACME, manual certs, SNI, ALPN
config.md Reviewed TOML config format, static/dynamic split, ArcSwap reload
operations.md Reviewed Rate limiting, logging, health check, systemd, shutdown

ADR Table

ADR Title Status
001 Rust with Axum Accepted
002 Custom Proxy Handler Accepted
003 TOML Configuration Format Accepted
004 ACME-Primary Certificate Management Accepted
005 tokio-rustls Directly, Not axum-server Accepted
006 Token Bucket Rate Limiting Accepted
007 Custom Structured Log Format Accepted
008 Static/Dynamic Config Split with ArcSwap Accepted
009 Signal Handling Strategy Accepted
010 Multi-Site Support in Phase 1 Accepted
011 Multi-Domain TLS Configuration Accepted
012 Restrict Cipher Suites to nginx Scope Accepted
013 Health Check on Separate Local Port Accepted
014 Unix Domain Socket Config Reload API Accepted
015 Per-Site Upstream Timeouts with Defaults Accepted
016 Explicit Bind Address Requirement Accepted
017 Upstream Connection Defaults Accepted
018 Request Body Size Limit Accepted
019 Multi-Config Listener Support Accepted
020 Container Deployment Model Accepted
021 X-Forwarded-For Edge Proxy Model Accepted
022 Health Check Scope — Local Port and Admin Socket Only Accepted
023 HTTP/2 Client-Facing Support Accepted
024 ANSI-Disabled Logging for Container Deployments Accepted

Open Questions

See open-questions.md for the full tracker.

OQ Question Priority Status
OQ-01 Should cipher suites be restricted beyond rustls defaults? medium resolved (ADR-012)
OQ-02 What log format should fail2ban consume? high resolved (ADR-007)
OQ-03 Should the health check endpoint be on a separate port? low resolved (ADR-013)
OQ-04 Config reload: SIGHUP only or also Unix socket API? low resolved (ADR-014)
OQ-05 Should the proxy bind to multiple addresses? low resolved (single bind_addr sufficient)
OQ-06 Should upstream timeouts be configurable per-site? low resolved (ADR-015)
OQ-07 Should per-site TLS overrides be supported for mixed ACME/manual domains? low resolved (ADR-019)
OQ-08 Should /health use a less common path to avoid upstream collision? medium resolved (ADR-022: no /health route on main listener)
OQ-09 How should upstream_connect_timeout_secs be enforced? medium resolved (implementation gap — ADR-015 already decides this)
OQ-10 Should ACME contact email be a required config field? high resolved (already specified in config.md; implementation bug C2)
OQ-11 How should X-Forwarded-Proto be derived per-listener? medium resolved (hardcoded https is correct for TLS-terminating proxy)
OQ-12 Should request access logging be mandatory or optional? high resolved (mandatory, always-on per operations.md)

Document Lifecycle

Status Meaning Transitions
draft Under active development. May change significantly. reviewed when open questions are resolved
reviewed Architecture is final. Implementation may begin. Changes require review. stable when implementation is complete
stable Locked. Changes require review and may warrant an ADR. deprecated when superseded
deprecated Superseded. Kept for reference. Removed when no longer referenced