minecraftd

Minecraft server daemonizer for systemd compatiblity

What dis?

This is a replacement for 'screen' when you run a Minecraft (or Spigot) using systemd (or any other init system).

Minecraftd daemonizes the minecraft server by capturing and buffering it's output, and giving commands to it, when needed. It also allows the administrator to access the server any time with a simple console.

Why dis?

I find it an ugly hack, to use screen with systemd, and I had weird issues with it. Since google led me nowhere with this problem, I decided to write my own script for it.

Features

• Service like start/stop/restart of a minecraft server. No more screens and tmuxes
• Easy to configure and run
• Attachable/detachable console with unix permissions
• Compatible with any flavour of minecraft server, or init system (example for systemd provided)

Usage

How to install & setup

Prerequirements

Git, python3, and pip3 are required by this software, so we install those first:

Debian

sudo apt install git python3 python3-pip

You'll also need java to run the minecraft server, but I assume you solved this already :)

Basic setup

First, clone the repo, and install minecraftd:

git clone https://github.com/marcsello/minecraftd.git
cd minecraftd
sudo ./install.sh

Next you should copy the example configuration file to it's place:
(in the folder you cloned the repo)

sudo cp minecraftd.json.example /etc/minecraftd.json

After that you should edit the config file:

sudo nano /etc/minecraftd.json

{

        "server": { // configurations related to your server
                "server_path" : "/opt/minecraft", // the path that contains your minecraft server
                "server_jar" : "server.jar", // the name of your server's jar file
                "java" : "java", // the command which launches java (usually java)

                "jvm_arguments" : [ // additional arguments to the JVM, only one argument per entry
                        "-XX:+UnlockExperimentalVMOptions",
                        "-XX:+UseG1GC",
                        "-XX:G1NewSizePercent=20",
                        "-XX:G1ReservePercent=20",
                        "-XX:MaxGCPauseMillis=50",
                        "-XX:G1HeapRegionSize=16M",
                        "-server",
                        "-Xms4G",
                        "-Xmx6G"
                ],


                "shutdown_commands" : [ // commands to run, when the daemon is about to shutdown
                        "save-all",
                        "stop"
                ]

        },

        "minecraftd": { // configurations related to minecraftd behaviour
		"logfile" : false, // Redirect logging from stderr to a file (won't ever needed probably)
                "console_socket_path" : "/var/lib/minecraftd/control.sock", // where to place the socket file that is used by the attachable console
                "history_length" : 10, // last n lines to transmit when a new client is connected (use false or null to disable)
                "log_level" : "INFO" // ... the log level
        }

}

You are done with the basic configuration of minecraftd
But you need to add it to your init system

If you are fine with the basic setup, you should change the "console_socket_path" entry in the above config to /tmp/mc.sock otherwise the daemon will fail to start, since we not created the default directory yet!

Installing systemd service

Now we need an user, that runs the minecraft server, and a system group which members are allowed to attach to the the console.

sudo groupadd -r minecraft
sudo useradd -d "YOUR MINECRAFT SERVER DIRECTORY" -M -r -s /bin/false -g minecraft minecraft

After that we should create the directory for the daemon's socket. (see the config above) We will give write permissions to the daemon user, and read permissions to it's group (so that anyone in the group can access to the socket):

sudo mkdir /var/lib/minecraftd
sudo chown minecraft:minecraft /var/lib/minecraftd
sudo chmod 750 /var/lib/minecraftd

Copy the systemd unit file to it's place:
(in the folder you cloned the repo)

sudo cp minecraftd.service.example /etc/systemd/system/minecraftd.service

And then enable and start it:

sudo systemctl daemon-reload
sudo systemctl enable minecraftd
sudo systemctl start minecraftd

Give permission to connect the server console

Add yourself to the minecraft group, so that you can use the console:

sudo usermod -a -G minecraft $USER

After that log out, and log back in.

And you are done! Enjoy your minecraft server!

How to use

When the minecraftd is running (and you have permission to access the console), you can access the console with the following command:

minecraftd

You can stop or restart the minecraft server with systemctl from now on:

sudo systemctl stop minecraftd
sudo systemctl restart minecraftd