Using the Raspberry Pi as a Minecraft server

The Vanilla Server

The vanilla server needs a Java environment as a pre-condition. If an SSH connection exists, then you should enter java -version in the terminal to control the Java installation. The Raspberry Pi will then communicate the version number of the installed Java environment. Raspbian automatically installs Java as part of the standard installation. If, however, command not found appears, you should install Java via:

sudo apt-get install oracle-java8-jdk

For security reasons, you should create a single user for the server and a new directory, which you then designate the home directory for the user. From the home directory, you should download the server software file minecraft_server.<Version>.jar [9] from the Internet and adjust the file access rights (Listing 1). Be careful to download the most recent version, which will ensure that the server has the latest functionality. Older servers are not always compatible with a current Minecraft client.

$ sudo adduser --system --no-create-home minecraft
$ sudo mkdir /opt/minecraft
$ sudo usermod -d /opt/minecraft minecraft
$ cd /opt/minecraft
$ sudo wget https://s3.amazonaws.com/Minecraft.Download\
  /versions/<Version>/minecraft_server.<Version>.jar
$ sudo chown minecraft:nogroup -R /opt/minecraft

Now the installation process is complete. Specifying a special user makes installation a bit more complex than many of the other installation instructions available over the Internet; however, on principle, server services should always run in the context of their own user because of security concerns.

Because a Java archive is involved, the server must be started via a Java command. The simplest way to do this is to change to the archive directory and invoke the program as shown in Listing 2. The screen session lets you close the terminal window after starting the service and detach from the session via Ctrl+A,D.

$ screen -S minecraft
$ cd /opt/minecraft
$ sudo -H -u minecraft java -Xmx256M -Xms256M -jar minecraft_server.1.8.7.jar
### In case of problems, you should start the server \
  without any additional parameters.
$ sudo -H -u minecraft java -jar minecraft_server.1.8.7.jar

When the vanilla server starts for the first time, you will immediately get an error message about the lack of consent to the end user license agreement (EULA). Here, the software installs the text file eula.txt in the directory; enter

sudo nano eula.txt

to open the file in the standard Nano editor, and change the eula=false line to eula=true. Then, save the change with Ctrl+O and confirm the file name with Enter. You should then return to the terminal with Ctrl+X and reinvoke the Minecraft server. It will now indicate in the console that it is ready to operate (Figure 1).

Figure 1: You can follow what is happening on the Minecraft server from the console. For example, you can see the creation of game worlds and logins by users.

Cuberite

Cuberite servers are installed in a similar fashion. One advantage of these servers is that a compiled version exists for the ARM processor. Additionally, Cuberite offers a web interface for the configuration process. With the vanilla server, you need to edit configuration files or use commands to work on them from the Minecraft client.

To install Cuberite, download the current build for ARM processors [10], create your own user account for Cuberite, and unpack the program to the /opt/ directory (Listing 3). The files and folders that appear still have outdated project names, such as /opt/MCServer/.

$ sudo adduser --system --no-create-home cuberite
$ sudo tar -xf Cuberite.tar.gz -C /opt
$ sudo usermod -d /opt/cuberite cuberite
$ sudo chown cuberite:nogroup -R /opt/MCServer

Next, you should invoke Cuberite inside of a Screen session and use the account installed previously (Listing 4). When it starts, the program will automatically install the settings file webadmin.ini for the web interface. The login data will be missing from this file because of security concerns. Thus, you should shut the server down from the terminal by pressing Ctrl+C and open the file in Nano:

$ screen -S cuberite
$ cd /opt/MCServer
$ sudo -H -u cuberite /opt/MCServer/MCServer

$ sudo nano /opt/MCServer/webadmin.ini

Once the file is opened, delete the leading semicolon that appears in front of the user name and enter a password for the admin account (Listing 5). Pressing Ctrl+O and Enter saves the changes you have made. You can return to the terminal via Ctrl+X.

; This file controls the webadmin feature of MCServer
; Username format: [User:*username*]
; Password format: Password=*password*
; for example:
[User:admin]
Password=topsecret
[WebAdmin]
Ports=8080
Enabled=1

From the terminal, you should start Cuberite again. This time, you log into the web interface (Figure 2) with a browser by using the URL http://localhost:8080 or generally via http://<IP-Address>:8080. You also need to use the previously assigned user data. Most of the entries are self-explanatory. Typically, you will not have to change anything when you start out. (See the box "Compiling Cuberite" for more information.)

Figure 2: The web interface in Cuberite is especially helpful for beginners who are starting out for the first time with a Minecraft server.