jrtechs-NodeJSBlog/content/posts/java/running-a-minecraft-server-with-docker.md

Close your eyes for one moment and imagine that everything you host runs in docker containers. You no longer need to battle system dependencies, and configurations are more manageable; it is now easier to backup and transfer your applications.

In my quest to dockerize everything, I am now dockerizing my Minecraft server. Minecraft is a relatively simple application to host since it is just a single Java application that you need to run. To put this in Docker, we need to declare a Java Docker image that launches our Minecraft server.

FROM openjdk:8u232

WORKDIR /root/minecraft

CMD java -Xmx2048M -jar spigot-1.10.jar -o true

To make this Docker container work, we need to mount the volume containing our Minecraft files to the path "/root/minecraft" in our Docker container. By mounting the volume, it enables us the persist the data between consecutive runs.

To orchestrate all of my Docker containers, I am using Docker-compose. Although there is only one container for this instance, I can add additional services to this file; for example, If I had a website that went along with my server, I could use docker-compose to launch both the Minecraft server and the server's website.

version: "2.2"

networks:
  bridge-network:
    external:
      name: bridge-network

services:
  minecraft:
    restart: always
    image: minecraft
    build: ./minecraft-docker
    networks:
      - bridge-network
    volumes:
      - "./minecraft:/root/minecraft"
    ports:
      - "8123:8123"
      - "25565:25565"

To expose the Minecraft server to the internet, we need to tell docker-compose the applications ports. I am using a bridged docker network along with appending the ports in the docker-compose configuration file. Port 25565 is the default Minecraft server port, and port 8123 gets used by Dynmap. To create the network bridge, you need to run this command once.

docker network create -d bridge bridge-network

We need to execute the build command to generate our new Minecraft Docker container:

docker-compose build

To launch the server, we just run the compose-up command.

docker-compose up

One quick note on the file structure that I am employing for this project: I like to keep the Dockerfiles in a directory separate from any volumes that I am mounting within those containers. Additionally, it is a good practice to have your docker-compose file at the root directory.

╭─jeff@dangerous ~/Docker 
╰─$ tree -L 2
.
├── docker-compose.yml
├── minecraft
│   ├── banned-ips.json
│   ├── banned-players.json
│   ├── bukkit.yml
│   ├── commands.yml
│   ├── crash-reports
│   ├── eula.txt
│   ├── logs
│   ├── ops.json
│   ├── permissions.yml
│   ├── plugins
│   ├── run.bat
│   ├── server-icon.png
│   ├── server.properties
│   ├── spigot-1.10.jar
│   ├── spigot.yml
│   ├── survival
├── minecraft-docker
│   └── Dockerfile
└── README.md

Docker will scan the entire director before building a project-- Docker does this so it knows what caches it can use during an incremental build. To improve the build time, I add the Minecraft server folder to the docker-ignore file to prevent Docker from scanning all the world artifacts.

# .dockerignore file
minecraft