Configuration

Guestroll is configured with environment variables only. Every variable is optional: an empty instance starts with safe defaults. A complete template is in .env.example.

Invalid values stop the server at startup with a message naming the variable, instead of running with a silent fallback.

Docker and network

These are read by the container or by docker-compose.yml, not by the app itself.

Variable	Default	Description
PORT	3000	Port the server listens on inside the container (or on the machine without Docker). The health check follows it.
HOSTNAME	0.0.0.0	Interface the server binds to inside the container.
HOST_PORT	3000	Compose only: port published on the host.
HOST_BIND	0.0.0.0	Compose only: host interface to publish on. 127.0.0.1 keeps Guestroll reachable only through a local reverse proxy.
DATA_PATH	guestroll-data	Compose only: named volume or host path mounted on /data.
PUID / PGID	1001	User and group that own the data folder and run the server. Match your host user for bind mounts.
TZ	UTC	Time zone of the stats (hourly and daily buckets), e.g. Europe/Paris.
GUESTROLL_IMAGE	ghcr.io/achedon12/guestroll:latest	Compose only: image to run. Pin a version in production.
CONTAINER_NAME	guestroll	Compose only: lets you run several instances side by side.

Instance

Variable	Default	Description
APP_NAME	Guestroll	Shown in page titles, the admin header and social cards.
PUBLIC_URL	(request host)	Public origin encoded in QR codes and social cards, e.g. https://photos.example.com. Set it: behind a proxy, the request host may be an internal name.
DATA_DIR	./data (/data in Docker)	Where the SQLite database and photos live.

Languages

Guestroll speaks English (en), French (fr), Italian (it) and Spanish (es). Each visitor gets, in this order:

1. the language they picked with the language menu (kept in their browser);
2. the album's language, if the hosts set one in the event settings;
3. their browser's language, if supported and DETECT_BROWSER_LOCALE is on;
4. DEFAULT_LOCALE.

Variable	Default	Description
DEFAULT_LOCALE	en	Language used when nothing more specific applies.
DETECT_BROWSER_LOCALE	true	false skips step 3: everyone without a choice gets the album's language or DEFAULT_LOCALE.

Security

Variable	Default	Description
ADMIN_PASSWORD	(generated)	Admin password. When set, it wins on every start and can't be changed from the UI. When empty, a password is generated on first start and printed once in the logs; change it in Admin → Settings.
SESSION_SECRET	(generated)	Key that signs and encrypts cookies, 32+ characters. When empty, one is generated and stored in DATA_DIR/.session-secret. Changing it signs everyone out.
TRUST_PROXY	false	Read the client IP from X-Forwarded-For and the host from X-Forwarded-Host. Turn it on only behind a reverse proxy you control, or rate limits can be dodged with a forged header.
SECURE_COOKIES	true in production	Cookies only travel over HTTPS. Set to false only to test over plain HTTP on a local network.

Uploads

Variable	Default	Description
MAX_UPLOAD_MB	25	Largest accepted photo. Phones resize before sending, so most uploads weigh 1–4 MB. Raise your reverse proxy's body limit above this.
MAX_IMAGE_MEGAPIXELS	80	Images above this are refused before decoding, which protects memory from "decompression bombs".
DEFAULT_CAPTURE_MODE	camera	Capture mode preselected for new events: camera, picker or both.

Rate limits

Per minute. Upload limits apply per guest, login limits per client IP.

Variable	Default	Description
RATE_LIMIT_UPLOADS_PER_MINUTE	30	Photos one guest can send per minute.
RATE_LIMIT_LOGIN_PER_MINUTE	5	Admin login attempts per IP.
RATE_LIMIT_UNLOCK_PER_MINUTE	10	Access-code attempts per guest; three times this value is the ceiling for wrong codes on one event, across all guests.

Email

Optional. Without SMTP, everything else works and no email is ever sent. SMTP can also be set in Admin → Settings → Email, where the password is stored encrypted (AES-256-GCM, key derived from SESSION_SECRET). When SMTP_HOST is set, the environment wins and the admin form is read-only.

Variable	Default	Description
SMTP_HOST	(none)	SMTP server, e.g. smtp.fastmail.com. Setting it turns email on.
SMTP_PORT	587	587 (STARTTLS) or 465 (TLS).
SMTP_SECURE	false	true for implicit TLS on port 465.
SMTP_USER / SMTP_PASSWORD	(none)	Credentials, when the server asks for them.
SMTP_FROM	SMTP_USER	Sender, e.g. Guestroll <photos@example.com>.
ADMIN_EMAIL	(none)	Where alerts and event summaries go. Settable in the admin when empty.
SCHEDULER_INTERVAL_SECONDS	60	How often the background worker sends queued mail, closes scheduled events and checks alerts. 0 turns it off.

Emails wait in a queue in the database and are retried after 1, 5, 15 minutes, 1 and 6 hours, then marked failed (Admin → Settings shows them, with a retry button). Set PUBLIC_URL: links in emails are built from it, since a background job has no request to read the host from.