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
DISABLE_RENDERING	Disable VNC rendering for performance	true
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)

Discord Integration

Variable	Description	Default
DISCORD_BOT_TOKEN	Discord bot token	-
DISCORD_BOT_NICKNAME	Custom bot nickname	(farm name)
DISCORD_CHAT_CHANNEL_ID	Channel ID for chat relay	-

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 =====
GAME_PORT=24642
QUERY_PORT=27015
VNC_PORT=5800
API_PORT=8080

# ===== Performance =====
DISABLE_RENDERING=true

# ===== Security (optional) =====
# SERVER_PASSWORD=your_server_password
# MAX_LOGIN_ATTEMPTS=3
# AUTH_TIMEOUT_SECONDS=120
# API_KEY=your_api_key

# ===== Discord (optional) =====
# DISCORD_BOT_TOKEN=your_bot_token
# DISCORD_BOT_NICKNAME=My Stardew Server
# DISCORD_CHAT_CHANNEL_ID=123456789012345678

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

Variable Details

DISABLE_RENDERING

Controls whether the server renders graphics to its own display. This does not affect players — they always see the game normally on their own screens.

Value	What happens
true (default)	Server skips drawing graphics. VNC shows black screen. Server works normally. Players connect and play as usual. Uses less CPU.
false	Server draws graphics. VNC shows game display. Only needed for debugging visual issues.

Why is this 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. The server's DISABLE_RENDERING setting only affects the server's own display (viewed via VNC).

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, all API endpoints require an Authorization: Bearer <api-key> header (except /health and /docs).

Generate a secure key:

bun -e "console.log(require('crypto').randomBytes(32).toString('base64url'))"

When do I need this?

Currently, only the Discord bot uses the API. If you:

• Use the Discord bot — Set the same API_KEY for both server and bot
• Don't use the Discord bot — You can skip API_KEY if the API port (8080) is not exposed externally
• Build custom integrations (web dashboard, monitoring, etc.) — Set API_KEY and include it in your requests

WARNING

Without API_KEY, anyone with network access to port 8080 can read server data and control your server. Always set this if the API is accessible from untrusted networks.

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
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 internal container ports remain unchanged — only the host mapping changes.

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

WARNING

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