Image & Ports
Configure the Docker image and port mappings for your game server.
Docker Image
Every game server runs a Docker image. The image is specified by two fields:
- Image Name — The repository path of the image (e.g.,
itzg/minecraft-server,ich777/steamcmd) - Image Tag — The version tag (e.g.,
latest,1.20.4,stable)
Together, these form the full image reference: itzg/minecraft-server:latest.
When you start a server, COSY pulls the image if it isn't already cached on the host. You can track the pull progress in real time from the UI.
Choosing an Image
Most game servers have community-maintained Docker images available on Docker Hub. When using a template, the image is pre-configured. For custom setups, search Docker Hub for your game.
Port Mappings
Ports define how players connect to your game server. Each port mapping consists of:
| Field | Description |
|---|---|
| Instance Port | The port on your host machine that maps to the container port |
| Container Port | The port inside the container that the game server listens on |
| Protocol | TCP or UDP — depends on the game |
Example
A Minecraft server typically uses:
| Container Port | Host Port | Protocol |
|---|---|---|
| 25565 | 25565 | TCP |
An ARK server might need multiple ports:
| Container Port | Host Port | Protocol |
|---|---|---|
| 7777 | 7777 | UDP |
| 7778 | 7778 | UDP |
| 27015 | 27015 | UDP |
Port Conflicts
Each host port can only be used by one container at a time. If you run multiple servers of the same game, you need to assign different host ports (e.g., 25565, 25566, 25567 for multiple Minecraft servers).