soulsync/Support/REVERSE-PROXY.md
BoulderBadgeDad aa3aae695d Security: opt-in reverse-proxy mode (ProxyFix + Secure cookie) + nginx guide
Tier 1 of "secure behind a reverse proxy". STRICTLY opt-in so direct/LAN installs
are byte-for-byte unchanged.

- core/security/reverse_proxy.py: apply_reverse_proxy_mode(app, config_get) — a
  no-op unless security.trust_reverse_proxy=true. When OFF (default), the app is
  untouched: no ProxyFix, X-Forwarded-* stays UNtrusted (a direct client can't
  spoof its IP/scheme), session cookie keeps Flask defaults. When ON (operator is
  behind nginx/Caddy/Traefik with TLS): trust one proxy hop's X-Forwarded-*, and
  mark the session cookie Secure + SameSite=Lax. Any config error → safe no-op,
  never breaks startup.
- Wired once at app init.
- Support/REVERSE-PROXY.md: nginx (with the Socket.IO Upgrade headers people
  always miss) / Caddy / Traefik configs, the setting, and the "put auth in front
  (Authelia/Authentik/oauth2-proxy)" recommendation + the off-for-plain-HTTP note.

Tests: off (and missing-key, and a config exception) is a strict no-op — not
ProxyFix-wrapped, cookie defaults intact; on wraps ProxyFix + secures the cookie;
and the real web_server app is NOT in proxy mode by default. 5 tests pass.
2026-06-10 20:36:49 -07:00

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Markdown

# Running SoulSync behind a reverse proxy (nginx / Caddy / Traefik)
Putting SoulSync behind a reverse proxy lets you serve it over **HTTPS** and — the
important part — put **authentication** in front of it before exposing it to the
internet. This guide covers the safe setup.
> **The golden rule:** the safest way to expose *any* self-hosted app publicly is
> to require authentication at the proxy (an auth layer), **not** to rely on the
> app's own protection. SoulSync's launch PIN is a useful fallback, but it is not
> a substitute for a real auth layer on a public instance.
---
## 1. Turn on reverse-proxy mode
By default SoulSync does **not** trust proxy headers (so a direct client can't spoof
its IP or pretend the connection is HTTPS). If you're behind a proxy that
terminates TLS, opt in by setting this in your `config.json`:
```json
{
"security": {
"trust_reverse_proxy": true
}
}
```
When enabled, SoulSync trusts `X-Forwarded-For/Proto/Host/Port` from **one** proxy
hop and marks its session cookie `Secure` (HTTPS-only) + `SameSite=Lax`. **Leave
it off if you access SoulSync directly over http:// on your LAN** — turning it on
would make the session cookie HTTPS-only and break plain-HTTP access.
Restart SoulSync after changing it.
---
## 2. nginx
SoulSync uses WebSockets (Socket.IO), so the `Upgrade`/`Connection` headers are
**required** — without them live updates silently stop working.
```nginx
server {
listen 443 ssl;
server_name soulsync.example.com;
ssl_certificate /etc/letsencrypt/live/soulsync.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/soulsync.example.com/privkey.pem;
# Large library scans / uploads
client_max_body_size 0;
location / {
proxy_pass http://127.0.0.1:8008;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Host $host;
# Required for Socket.IO / live updates
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_read_timeout 3600s; # long-running scans
proxy_send_timeout 3600s;
}
}
```
---
## 3. Caddy
Caddy handles TLS automatically and proxies WebSockets out of the box:
```caddy
soulsync.example.com {
reverse_proxy 127.0.0.1:8008
}
```
Caddy sets `X-Forwarded-*` for you. (Add an auth provider directive if you want
auth at the proxy — see below.)
---
## 4. Traefik
Traefik proxies WebSockets automatically and forwards the headers. Point a router
at the SoulSync service on port `8008` with your TLS resolver; no extra WebSocket
config is needed.
---
## 5. Add authentication in front (recommended for public instances)
Pick one:
- **Auth proxy** — [Authelia](https://www.authelia.com/),
[Authentik](https://goauthentik.io/), or
[oauth2-proxy](https://oauth2-proxy.github.io/oauth2-proxy/). These sit in front
of SoulSync and force a login (with 2FA) before any request reaches it. Best
option for internet exposure.
- **HTTP Basic Auth** — quick and simple (nginx `auth_basic` / Caddy `basicauth`).
Better than nothing; weaker than an auth proxy.
- **SoulSync launch PIN** — set an admin PIN in Settings. Enforced server-side, so
it can't be bypassed by hitting the API directly — but it's a shared PIN, so
treat it as a fallback, not your only gate.
---
## Troubleshooting
- **Live updates / progress bars don't move** → the WebSocket `Upgrade`/`Connection`
headers are missing (nginx) or your proxy is buffering. Check section 2.
- **Login won't stick / "session expired"** → you enabled `trust_reverse_proxy` but
are reaching SoulSync over plain `http://`. The session cookie is now HTTPS-only;
use `https://`, or turn the setting off for direct HTTP access.
- **Scans time out** → raise `proxy_read_timeout` / `proxy_send_timeout`.