| `HOST` | Bind address for the HTTP server (e.g. `127.0.0.1`, `10.0.0.72`). **Source / Proxmox installs only** — do not set this in Docker or any containerized deployment. See note below. | all interfaces |
| `DEFAULT_LANGUAGE` | Default language on the login page — see supported codes below | `en` |
| `ALLOWED_ORIGINS` | Comma-separated origins for CORS and email notification links | same-origin |
| `ALLOW_INTERNAL_NETWORK` | Allow outbound requests to private/RFC-1918 IPs. Set `true` if Immich or other integrated services are on your local network. Loopback (`127.x`) and link-local (`169.254.x`) addresses remain blocked regardless. | `false` |
| `APP_URL` | Public base URL (e.g. `https://trek.example.com`). Required when OIDC is enabled — must match the redirect URI registered with your IdP. Also used as the base URL for email notification links. | — |
By default TREK binds to all network interfaces (`0.0.0.0`), which is the correct behaviour inside a container because Docker handles port exposure at the host level. Setting `HOST` overrides the bind address at the Node.js level.
**When to use it:** only when running TREK directly on a host (git sources or the [Proxmox community script](Install-Proxmox)) and you need to restrict which interface the server listens on — for example, to expose TREK only on a LAN interface while keeping it off the public-facing one.
**Never set `HOST` in Docker, Docker Compose, Helm, or Unraid deployments.** Use Docker's `-p <host-ip>:<host-port>:<container-port>` syntax or your orchestrator's port binding instead.
```
# .env — source / Proxmox installs only
HOST=10.0.0.72 # bind only on this LAN interface
PORT=3001
```
When `HOST` is set, the startup banner includes a `Host:` line confirming the bound address.
2.**`data/.encryption_key` file** — present on any install that has started at least once.
3.**`data/.jwt_secret` file** — one-time fallback for existing installs upgrading without a pre-set key. The value is immediately persisted to `data/.encryption_key` so JWT rotation cannot break decryption later.
4.**Auto-generated** — fresh install with none of the above; persisted to `data/.encryption_key`.
Setting `ENCRYPTION_KEY` explicitly is recommended so you can back it up independently of the data volume.
> **Note:** `id` (Indonesian / Bahasa Indonesia) appears in `client/src/i18n/supportedLanguages.ts` but is not in the server's supported-codes list in `config.ts`. Setting `DEFAULT_LANGUAGE=id` will fall back to `en` with a warning in the server log.
| `HSTS_INCLUDE_SUBDOMAINS` | When `true`: adds the `includeSubDomains` directive to the HSTS header, extending HTTPS enforcement to all subdomains. Only effective when HSTS is active (`FORCE_HTTPS=true` or `NODE_ENV=production`). Leave `false` if you run other services on sibling subdomains over plain HTTP. | `false` |
| `TRUST_PROXY` | Number of trusted proxy hops. Tells Express to read the real client IP from `X-Forwarded-For` and protocol from `X-Forwarded-Proto`. Defaults to `1` automatically in production. Required for `FORCE_HTTPS` to detect the forwarded protocol. | `1` (production) |
| `COOKIE_SECURE` | Controls the `secure` flag on the `trek_session` cookie. Auto-derived as `true` when `NODE_ENV=production` or `FORCE_HTTPS=true`. Set to `false` only as an escape hatch for LAN testing without TLS — not recommended in production. | auto |
> **Warning:** `FORCE_HTTPS=true` without `TRUST_PROXY` set causes a redirect loop.
| `OIDC_DISPLAY_NAME` | Label shown on the SSO login button | `SSO` |
| `OIDC_ONLY` | Force SSO-only mode: disables password login and registration, overrides Admin > Settings toggles, cannot be changed at runtime. First SSO login becomes admin on a fresh instance. | `false` |
| `OIDC_ADMIN_CLAIM` | OIDC claim used to identify admin users (e.g. `groups`) | — |
| `OIDC_ADMIN_VALUE` | Value of the OIDC claim that grants admin role (e.g. `app-trek-admins`) | — |
| `OIDC_SCOPE` | Space-separated OIDC scopes to request. **Fully replaces** the default — always include `openid email profile` plus any extra scopes (e.g. add `groups` when using `OIDC_ADMIN_CLAIM`) | `openid email profile` |
| `OIDC_DISCOVERY_URL` | Override the auto-constructed OIDC discovery endpoint. Required for providers with a non-standard path (e.g. Authentik) | — |
---
## Email / SMTP
SMTP settings can be configured via the Admin panel or overridden with environment variables. Env vars take priority over the database values.
| `SMTP_SKIP_TLS_VERIFY` | Set `true` to disable TLS certificate validation. Useful for self-signed certs on internal SMTP relays — not recommended in production. | `false` |
`SMTP_HOST`, `SMTP_PORT`, and `SMTP_FROM` are all required for email delivery to work. `SMTP_USER` and `SMTP_PASS` are optional (for unauthenticated relays).
---
## Initial Setup
These variables only take effect on first boot, before any user exists.
| Variable | Description | Default |
|---|---|---|
| `ADMIN_EMAIL` | Email for the first admin account | `admin@trek.local` |
| `ADMIN_PASSWORD` | Password for the first admin account | random |
Both variables must be set together. If either is omitted, the account is created with email `admin@trek.local` and a randomly generated password that is printed to the server log. Once any user exists, these variables have no effect.
