Minecraft Server on Docker ⛏ 🐳

Introduction

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Minecraft is a great game that becomes even more enjoyable when played with friends. One of the best ways to do this is by setting up a dedicated server. This guide will help you do just that!

Setting up and running a Minecraft server does not require a lot of resources, but based on my experience, allocating more resources significantly enhances performance, especially when you start to add mods and increase player count.

Prerequisites

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• Docker
• Docker Compose

For more information about my Docker setup, see Pi Cluster

Requirements

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Requirements Gathered from here

Minimum (1-5 Players)

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- Intel Pentium 4 or AMD Athlon based CPU
- 512 MB RAM
- 2 GB Storage space

Recommended (10-15 Players)

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- Intel Core or AMD K8 based CPU
- 3 GB RAM
- 16 GB Storage Space

Optimal (20+ Players)

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- Intel i5/i7 or AMD Ryzen 5/7 Based CPU
- 6 GB RAM
- 35 GB Storage Space

My opinion:

I personally went with the optimal settings as I wanted to run mods as well as have the capacity for ~10 players. This gives the server breathing room.

However, if you will be running no mods or only a few lightweight mods and only a few players, there is no need to go higher than 3-4 GB.

Building the Container

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Let’s get started on building the Minecraft server.

1. Create a directory for the Minecraft server files:

# Make the folder
mkdir minecraft-server
# Enter the folder
cd minecraft-server

2. Create an environment file for the Docker Container:

• The .env file allows us to specify variables used in the build process.

# Create a .env file
touch .env
# Open in a text editor
vim .env
# Enter the following variables
CONTAINER_NAME=minecraft-server
SERVER_MEM=4096 # Change this to your desired value (in MB)
SERVER_JAR=<downloaded-server-file>.jar # Minecraft server jar file. Change this later

3. Create the docker-compose.yml file:

# Create the file
touch docker-compose.yml
# Open in a text editor
vim docker-compose.yml

• docker-compose.yml specifies the configuration of our Minecraft server: - Build a Docker image using the current context and pass some arguments. - Attach the volume .server-data where Minecraft’s files will be stored. - Open network ports to access the Docker container. - Name the Docker container. - Ensure the container always restarts unless explicitly stopped.

services:
  minecraft-server:
    build:
      context: .
      args:
        SERVER_MEM: ${SERVER_MEM}
        SERVER_JAR: ${SERVER_JAR}
    volumes:
      - .server-data:/server
    ports:
      - 25565:25565 # Game
      - 25575:25575 # RCON
    container_name: ${CONTAINER_NAME}
    restart: unless-stopped

volumes:
  server-data:

4. Create the Dockerfile:

• Referenced in the docker-compose.yml build stage as context ..
• The Dockerfile specifies the software running inside the container.

# Create the file
touch Dockerfile
# Open the file in a text editor
vim Dockerfile

• Use the eclipse-temurin:21 image to provide the Java JRE - Use the required Java version for the version of Minecraft you are running.
• Collect the arguments from the .env file.
• Set the environment variables.
• Set the working directory to /server, on our local system is .server-data.
• Run the Minecraft server jar with the environment variables.

FROM eclipse-temurin:21

ARG SERVER_MEM
ARG SERVER_JAR

ENV SERVER_MEM=${SERVER_MEM}
ENV SERVER_JAR=${SERVER_JAR}

WORKDIR /server

CMD echo "Minecraft Server is starting\n" && java -Xms128M -Xmx${SERVER_MEM}M -jar ${SERVER_JAR} nogui

Setup the Server Files

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We’re almost there, just a few steps to go.

When you try to start the container, you might encounter the following error:

Minecraft Server is starting

Error: Unable to access jarfile server.jar

This happens because we haven’t downloaded the server jar file yet. Let’s do that now.

1. Create a folder in the minecraft-server directory called .server-data:

mkdir .server-data
cd .server-data

2. Download a Minecraft server jar file:

• Vanilla Minecraft Server - Right-click the green link that says minecraft_server..jar and copy the link address. - Download with: curl -o server.jar
• Fabric Mod loader server - Select the Minecraft version, Fabric Loader Version, and the Installer Version of your choice. I tend to go with the latest. - Download with: Copy the curl command under CLI download

3. Go back to the root minecraft-server directory:

cd ..

4. Edit SERVER_JAR in .env with the name of the server file you just downloaded:

# Open in a text editor
vim .env
# Enter the following variables
CONTAINER_NAME=minecraft-server
SERVER_MEM=4096
SERVER_JAR=<downloaded-server-file>.jar # Change this to the name of the .jar you downloaded

5. Run the container to generate necessary files like eula.txt:

docker compose up

You will see something like this:

minecraft-server  | Starting net.minecraft.server.Main
minecraft-server  | [18:05:50] [ServerMain/INFO]: You need to agree to the EULA in order to run the server. Go to eula.txt for more info.
minecraft-server exited with code 0

6. Accept the EULA:

# Edit eula.txt in a text editor
vim .server-data/eula.txt
# Change `eula=false` to `eula=true`
eula=true

7. Make any additional changes you want:

• Notable files: - server.properties - Configure server name, game mode, world type, etc. - ops.json - Server operators (can be set in-game). - whitelist.json - Players allowed to join the server (can be set in-game).

Run the Server

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Run the container in detached mode:

# The -d flag allows the container to run in detached mode, i.e., in the background
docker compose up -d

To monitor the logs as the server starts:

# Monitor the logs as the server starts. Use CTRL+C to exit
docker logs minecraft-server --follow
# If you see the following lines, your server is up and running:
    [18:17:01] [Server thread/INFO]: Time elapsed: 25529 ms
    [18:17:01] [Server thread/INFO]: Done (34.571s)! For help, type "help"

Conclusion

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Congratulations! You’ve successfully set up a Minecraft server. Now it’s time to play!

There are many exciting possibilities from here, such as installing mods or creating scripts to manage the server. Enjoy your Minecraft adventures!