Environment Variables

Environment variables in the .env file control Docker infrastructure, credentials, and networking. They are not used for game settings (use server-settings.json for those).

Required Variables

These must be set for the server to function:

Variable	Description
STEAM_USERNAME	Steam account username
STEAM_PASSWORD	Steam account password
VNC_PASSWORD	Password for VNC web interface

Runtime Variables

Variable	Description	Default
GAME_PORT	UDP port for multiplayer connections	24642
QUERY_PORT	UDP port for Steam query protocol	27015
VNC_PORT	TCP port for VNC web interface	5800
API_PORT	Port for the HTTP REST API	8080
API_ENABLED	Enable HTTP API for external tools	true
PUBLIC_HOST	Public IP or domain of the HTTPS proxy; when set, VNC_PORT and API_PORT bind to loopback	-
SERVER_NAME	Display name shown as the Discord bot nickname and on status widgets	(farm name)
SERVER_URL_NAME	This server's name in its URL behind the proxy	server
PROXY_ROUTING	path (https://HOST/NAME/) or subdomain (https://NAME.HOST/)	path
COMPOSE_PROFILES	proxy starts the bundled HTTPS proxy; leave unset to use your own	-
SERVER_FPS	Render rate: 0 = rendering disabled, N > 0 = render at N fps	0
VERBOSE_LOGGING	Override verbose logging setting	-

Security Variables

Variable	Description	Default
STEAM_REFRESH_TOKEN	Pre-existing refresh token (for CI/automation)	-
SERVER_PASSWORD	Server password for player authentication	(empty = disabled)
MAX_LOGIN_ATTEMPTS	Failed login attempts before kick	3
AUTH_TIMEOUT_SECONDS	Seconds before unauthenticated players are kicked	120
API_KEY	API key for authenticating write requests	(empty = disabled)
ALLOW_INSECURE_SETUP	Allow startup when VNC_PASSWORD or API_KEY is empty	false

Host / Permissions

Variable	Description	Default
USER_ID	User ID (UID) the game runs as inside the container	1000
GROUP_ID	Group ID (GID) of that user	1000

The game runs as a normal user inside the container rather than as root, so a misbehaving mod cannot touch anything outside the game's own files. The container starts as root only long enough to prepare the server's files and assign their ownership.

On Linux, files written to .local-container/settings and diagnostics are owned by this UID/GID on the host as well, so set them to your own user and group to access those files normally.

• Windows and macOS: no configuration required. Docker Desktop handles file ownership for you.

• Linux: set both values to your user and group IDs. If both commands print 1000, the defaults are already correct.

  id -u   # USER_ID
  id -g   # GROUP_ID

• Rootless Docker: set both to 0. In rootless Docker, UID/GID 0 inside the container maps to your host user.

• Root: setting both to 0 on regular Docker runs the game as root inside the container. Not needed; on Linux the two folders above are then owned by root on the host.

You can change the values later. On the next start, the container updates the ownership of the server's files to match.

Discord Integration

Variable	Description	Default
DISCORD_BOT_TOKEN	Discord bot token	-
DISCORD_CHAT_CHANNEL_ID	Channel ID for chat relay	-
STATUS_DASHBOARD_CHANNEL_ID	Channel ID for the status dashboard	-
STATUS_DASHBOARD_REFRESH_RATE	Dashboard update interval in seconds	30

See Discord Integration for setup instructions.

Example .env File

# ===== Required =====
STEAM_USERNAME=your_steam_username
STEAM_PASSWORD=your_steam_password
VNC_PASSWORD=your_secure_password

# ===== Ports (uncomment to change from defaults) =====
# GAME_PORT=24642
# QUERY_PORT=27015
# VNC_PORT=5800
# API_PORT=8080

# ===== Performance (uncomment to change from defaults) =====
# SERVER_FPS=10

# ===== Security (optional) =====
# SERVER_PASSWORD=your_server_password
# API_KEY=your_api_key

# ===== Discord (optional) =====
# DISCORD_BOT_TOKEN=your_bot_token
# DISCORD_CHAT_CHANNEL_ID=123456789012345678
# STATUS_DASHBOARD_CHANNEL_ID=123456789012345678

# ===== CI/Automation (optional) =====
# STEAM_REFRESH_TOKEN=your_refresh_token

Variable Details

SERVER_FPS

Controls the rate at which the server draws graphics to its own display. This does not affect players — they always see the game normally on their own screens.

Value	What happens
0 (default)	Rendering disabled. The server installs a null display device and suppresses draws; VNC shows a "Rendering Disabled" notice. The server works normally — players connect and play as usual — and it uses less CPU.
N > 0	Server draws at up to N frames per second. VNC shows the game display. Useful for debugging visual issues; a low value like 10 keeps CPU cost modest.

Why is 0 the default?

A dedicated server doesn't need to display anything. It just processes game logic and sends updates to players. Skipping the graphics rendering saves significant CPU resources.

Players are not affected

When you connect to the server with your game client, you see the game on your screen rendered by your computer. SERVER_FPS only affects the server's own display (viewed via VNC).

Changing the rate at runtime

You don't have to restart to enable rendering for debugging. Both of these take effect immediately:

• HTTP: POST /rendering?fps=10 (use fps=0 to disable again).
• Console: docker compose exec server attach-cli, then rendering 10 (or rendering 0, rendering status).

Driving the game over VNC

While rendering is off (SERVER_FPS=0), VNC input is fully suppressed — there is nothing to see, so input has no meaning. While rendering is on, the VNC view is input-blocked except F9 (toggle host automation) and F10 (toggle visibility). Press F9 to drop automation and gain full keyboard/mouse control; press it again to re-arm the guard.

STEAM_REFRESH_TOKEN

Alternative to username/password for automated environments. Export after initial setup:

docker compose run --rm steam-auth export-token

See Steam Authentication for CI/CD usage.

SERVER_PASSWORD

When set, players must authenticate with !login <password> before they can play. Leave empty to disable password protection.

See Password Protection for full documentation.

API_ENABLED

When true, the REST API is available for external tools and monitoring. See REST API for endpoints.

API_KEY

When set, API endpoints require an Authorization: Bearer <api-key> header. The API reference marks which endpoints are public.

Generate a secure key:

openssl rand -base64 32

Who needs the key

• Discord bot: set the same API_KEY for the server and the bot.
• diagnostics command: reads the key from the container environment.
• Your own integrations: send the Authorization header.

ALLOW_INSECURE_SETUP

The server refuses to start without VNC_PASSWORD, or without API_KEY while API_ENABLED=true. Set ALLOW_INSECURE_SETUP=true to start anyway. Only do this on networks where the VNC and API ports are not reachable by untrusted clients.

Port Summary

Port	Protocol	Purpose	Expose Externally?
24642	UDP	Game (Steam SDR)	No (relay handles NAT)
27015	UDP	Steam query	No (relay handles NAT)
5800	TCP	VNC web interface	Only for remote access
8080	TCP	REST API	Only for external tools
80, 443	TCP	HTTPS proxy (optional)	Only with the proxy profile
3001	TCP	Steam auth (internal)	No

Changing Ports

To avoid port conflicts, you can change the host-side mappings in .env:

VNC_PORT=5801
API_PORT=8081

The VNC container port stays fixed; only its host mapping changes. API_PORT changes the API port both on the host and inside the container, so the server, its health check, and the Discord bot all follow it.

Advanced Variables

These are rarely needed but available for advanced use cases:

Variable	Description	Default
HEALTH_CHECK_SECONDS	Interval for internal health checks	300
ENABLE_MOD_INCOMPATIBLE_OPTIMIZATIONS	Enable performance optimizations that may break some mods	true
FORCE_NEW_DEBUG_GAME	Force creation of a new debug game on startup	false
AUTO_SLEEP_GRACE_SECONDS	Wall-clock seconds an empty server waits past 1:00 AM in-game before the host sleeps and closes the day	300

WARNING

These variables are for advanced users. Changing them may cause unexpected behavior.