Core Keeper Dedicated Server

Explore an endless cavern of creatures, relics and resources in a mining sandbox adventure for 1-8 players. Mine, build, fight, craft and farm to unravel the mystery of the ancient Core. Get Core Keeper at the Steam Store

Supported tags and respective Dockerfile links

• latest (Dockerfile)

How to run

ARM based configuration

This image currently includes the following Box64 build variants for the following devices:

• Generic [generic]
• Raspberry Pi 3 [rpi3]
• Raspberry Pi 4 [rpi4-pre3]
• Raspberry Pi 5 (4K page size) [rpi5]
• Raspberry Pi 5 (16K page size) [rpi5_16k]
• M1 (M-Series) Mac [m1]
• ADLink Ampere Altra (Oracle ARM CPUs) [adlink]

By default it is set to use generic. If you want to use another one, change the enviromental variable ARM64_DEVICE at the core.env file.

Volumes

Create two directories where you want to run your server :

• server-data: mandatory if you want to keep configuration between each restart
• server-files: optional, contains all the files of the application

Then modify /host/path/to/server-data and/or /host/path/to/server-files in one of the examples below to match the paths of the folders you created.

Using Docker CLI:

docker run -d \
  --name core-keeper-dedicated \
  -e WORLD_NAME="Core Keeper Server" \
  -e MAX_PLAYERS=5 \
  -v /host/path/to/server-data:/home/steam/core-keeper-data \
  -v /host/path/to/server-files:/home/steam/core-keeper-dedicated \
  escaping/core-keeper-dedicated:latest

Using Docker Compose

Create a docker-compose.yml with the following content:

services:
  core-keeper:
    image: escaping/core-keeper-dedicated:latest
    container_name: core-keeper-dedicated
    restart: unless-stopped
    stop_grace_period: 2m
    # Port is only needed if using direct connection mode
    # ports:
    #   - "$SERVER_PORT:$SERVER_PORT/udp"
    volumes:
      - /host/path/to/server-files:/home/steam/core-keeper-dedicated
      - /host/path/to/server-data:/home/steam/core-keeper-data
    env_file:
      - path: core.env
        required: false

Create a core.env file and override the desired environmental variables for the dedicated server, see configuration for reference. Example:

ARM64_DEVICE=rpi5
MAX_PLAYERS=3

On the folder which contains the files run docker compose up -d.

A GameID.txt file will be created next to the executable containing the Game ID. If it doesn't appear you can check the docker logs (docker logs core-keeper-dedicated or docker compose logs) for errors.

To query the game ID run: docker exec -it core-keeper-dedicated cat /home/steam/core-keeper-dedicated/GameID.txt

Configuration

These are the arguments you can use to customize server behavior with default values.

Argument	Default	Description
PUID	1000	The user ID on the host that the container should use for file ownership and permissions.
PGID	1000	The group ID on the host that the container should use for file ownership and permissions.
ARM64_DEVICE	generic	The Box64 build variants. Accepts generic, rpi5, m1 and adlink.
USE_DEPOT_DOWNLOADER	false	Use Depot downloader instead of steamcmd. Useful for system not compatible with 32 bits.
WORLD_INDEX	0	Which world index to use.
WORLD_NAME	"Core Keeper Server"	The name to use for the server.
WORLD_SEED	""	The seed to use for a new world. Set to "" to generate random seed.
HASHED_WORLD_SEED	""	The hashed seed to use for a new world, added in v1.1. Set to "" to generate random seed.
WORLD_MODE	0	Sets the world mode for the world. Can be Normal (0), Hard (1), Creative (2), Casual (4).
SEASON	No Default	Overrides current season by setting to any of None (0), Easter (1), Halloween (2), Christmas (3), Valentine (4), Anniversary (5), CherryBlossom (6), LunarNewYear(7). Do not set this env var if you want real date season.
GAME_ID	""	Game ID to use for the server. Need to be at least 15 characters, no longer than 28 characters and alphanumeric, excluding I,l,Y,y,x,0,O,o. Empty or not valid means a new ID will be generated at start.
MAX_PLAYERS	10	Maximum number of players that will be allowed to connect to server.
SERVER_IP	No Default	Only used if port is set. Sets the address that the server will bind to.
SERVER_PORT	No Default	Port used for direct connection mode. Setting an value to this will cause the server behaviour to change! See Network Mode
PASSWORD	No Default	Password players should use when trying to join using direct connections. Maximum length password can be 28 characters. If omitted or invalid, a random password will be generated.
ALLOW_ONLY_PLATFORM	No Default	Allow only players from given platform. If not set all platforms are allowed. Has no effect unless -port is also set enabling Direct Connections. Can be Steam (1), Epic (2), Microsoft (3), GOG (4).
DISCORD_WEBHOOK_URL	""	Webhook url (Edit channel > Integrations > Create Webhook).
DISCORD_PLAYER_JOIN_ENABLED	true	Enable/Disable message on player join
DISCORD_PLAYER_JOIN_MESSAGE	"$${char_name} ($${steamid}) has joined the server."	Embed message
DISCORD_PLAYER_JOIN_TITLE	"Player Joined"	Embed title
DISCORD_PLAYER_JOIN_COLOR	"47456"	Embed color
DISCORD_PLAYER_LEAVE_ENABLED	true	Enable/Disable message on player leave
DISCORD_PLAYER_LEAVE_MESSAGE	"$${char_name} ($${steamid}) has disconnected. Reason: $${reason}."	Embed message
DISCORD_PLAYER_LEAVE_TITLE	"Player Left"	Embed title
DISCORD_PLAYER_LEAVE_COLOR	"11477760"	Embed color
DISCORD_SERVER_START_ENABLED	true	Enable/Disable message on server start
DISCORD_SERVER_START_MESSAGE	"**World:** $${world_name}\n**GameID:** $${gameid}"	Embed message. Available variables are world_name, gameid, (the following only in direct connection mode) allowed_platforms, public_ip, port, password, join_string
DISCORD_SERVER_START_TITLE	"Server Started"	Embed title
DISCORD_SERVER_START_COLOR	"2013440"	Embed color
DISCORD_SERVER_STOP_ENABLED	true	Enable/Disable message on server stop
DISCORD_SERVER_STOP_MESSAGE	""	Embed message
DISCORD_SERVER_STOP_TITLE	"Server Stopped"	Embed title
DISCORD_SERVER_STOP_COLOR	"12779520"	Embed color
MODS_ENABLED	false	Enable/Disable mod support
MODIO_API_KEY	""	mod.io API key
MODIO_API_URL	""	mod.io API path
MODS	""	List of mods to install
ACTIVATE_CONTENT	""	Comma separated list to turn on biomes for worlds created prior to v1.1. Valid values are GiantCicadaBossDungeon, NatureBiomeCicadas, GuaranteedOases, and AbioticFactor. Once enabled, they cannot be disabled!

Mod Support

The container supports automatically installing mods from mod.io.

1. Get a mod.io API key from mod.io/me/access
   • You'll need the API path that is generated along with the key (e.g. https://u-*.modapi.io/v1)
2. Set the necessary environment variables in your core.env file (or in your docker-compose.yml)

• MODS_ENABLED=true
• MODIO_API_KEY=your_api_key
• MODIO_API_URL=your_api_url
• MODS=mod1,mod2 (see below)

Specify mods to install

Warning

Installing a client-only mod can cause the server to not start. Don't install client-only mods (they wouldn't do anything on the server anyway).

Important

Mod dependencies are not automatically installed. You must look at the dependencies for each mod you want to install and add their dependencies to the list.

You'll need to get the mod string ID from mod.io for each mod you want to install. The easiest way to do this is to grab it from the URL.

For example, looking at the URL for CoreLib (https://mod.io/g/corekeeper/m/core-lib), you would use core-lib.

Specify mods as a comma-separated list, optionally providing a version:

# Format: <mod_id>[:<version>], ...
MODS=core-lib,coreliblocalization,corelibrewiredextension,ck-qol

Example using specific versions:

MODS=core-lib,coreliblocalization,corelibrewiredextension:3.0.1,ck-qol:1.9.4

• If version is not specified, the latest version will be installed.
• Mods are reinstalled whenever the container is started, so to update mods to their latest version, simply restart the container.

Network Mode

Currently Core Keeper supports two network modes: SDR (Steam Datagram Relay) and Direct Connect.

SDR (Steam Datagram Relay)

In this mode, the server uses Valve's Virtual Network to route traffic through Steam's relay infrastructure. Instead of players connecting directly to the server's IP address, all communication goes through secure relay nodes managed by Steam. This hides the server’s real IP, protects against DDoS attacks, and improves NAT traversal.

Because of this relay system, server operators do not need to open any ports on their router or firewall—as long as outbound connections to Steam are allowed, the server can communicate with clients reliably.

Direct Connection

In Direct Connect mode, players connect straight to the server’s public IP address without going through Steam's relay network. This can result in lower latency and more direct communication, but it requires the server to be reachable from the internet.

Server operators must open and forward the necessary ports on their router or firewall to allow incoming connections. Unlike SDR, this mode exposes the server’s IP address to clients and may be more vulnerable to connection issues or attacks.

Important

The SERVER_PORT environment variable determines the server's network mode.
Leave it empty to use SDR (no port forwarding needed).
Setting a value switches to Direct Connect, which requires opening and forwarding ports.
Only set this if you specifically want Direct Connect.

Contributors

Made with contrib.rocks.