A lightweight, serverless Minecraft server watcher and auto-starter.

mcservernap monitors incoming Minecraft client connections and automatically launches (and later stops) a local Minecraft server process via RCON. It enables you to avoid running your server 24/7 by:

• Listening for the first legitimate Minecraft LoginStart handshake.
• Spinning up the server process on-demand when a player attempts to join.
• Watching the server via RCON for player activity.
• Stopping the server after an idle timeout.

There is also a stop subcommand to immediately send a /stop command via RCON.

• On-demand startup: server only runs when a player actually joins.
• Idle shutdown: automatically stops server when no players remain for a set duration.
• Cross-platform: spawns a new terminal window on Windows, runs directly on Linux systems.
• Extensible: configure RCON settings, startup command and ports.

1. Ensure you have Rust and Cargo installed (see rustup.rs).

2. Clone this repository:

   git clone https://github.com/yourusername/MCServerNap.git
   cd MCServerNap

3. Build the binary:

   cargo build --release

   The executable can be found under target/release/mcservernap.exe

4. (Optional) If you wish to install globally:

   cargo install --path .

mcservernap <COMMAND> [OPTIONS]

• listen — Listen for incoming connections and start the server on first join.
• stop — Immediately send a /stop command via RCON to shut down an already-running server.

mcservernap listen 0.0.0.0 25565 --server-port 25566 --rcon-port 25575 --rcon-pass rconpasswordmeow java -- -Xmx5G -Xms5G -jar server.jar nogui

mcservernap listen 0.0.0.0 25565 "C:\path\to\your\script\start_server.bat" --server-port 25566 --rcon-port 25575 --rcon-pass rconpasswordmeow

IMPORTANT: When using a script, make sure the script closes its window at the end of the script (Windows .bat example: exit), or else this application won't detect that the Minecraft server process has shut down!

Once a client sends a LoginStart packet, the tool:

1. Drops the listener and launches your server command.
2. Starts an idle watchdog task that polls RCON according to rcon_poll_interval.
3. If no players remain for the defined amount of rcon_idle_timeout time, sends /stop and exits.

mcservernap stop --rcon-port 25575 --rcon-pass rconpasswordmeow

This immediately connects via RCON and sends the /stop command.

env_logger::Builder::from_default_env()
        .filter_level(log::LevelFilter::Info) // Change this LevelFilter to change logging level (e.g. Debug)
        .init();

You need to rebuild the project for the change to take effect.

Configuration Options:

• Timeouts & Intervals: set via rcon_idle_timeout and rcon_poll_interval in seconds
• Message of the day (MOTD): The message shown to the user in the server browser menu. set via motd_text, motd_color and motd_bold
• Connection Message: The message shown to the user when they try to connect. Set via connection_msg_text, connection_msg_color and connection_msg_bold
• Server Icon: The icon of the server within the server browser menu. Set by inserting a .png file in the config/ folder with the name server-icon.png. The image must be 64x64 pixels big. If it's not, this application will automatically resize the image to meet this requirement
• Configuration Directory: The location of the cfg.toml can be changed from the standard config/ directory by editing the value of config_directory_name. This will delete the previous directory and move the files to the new one

Contributions are welcome! Feel free to open issues or pull requests to:

• Support TLS or SSH tunnels for RCON

This project is licensed under the MIT License. See LICENSE for details.