Running a Minecraft Server with Docker on Ubuntu

Managing your Mincraft server with docker is a little bit nicer than just using the old "screen -r Mincraft" trick. docker can do snaphoting and auto restarting, and will allow you to think of the Mincraft server as a service, not just a java file that is being executed. Heres how I built mine. You should not have to edit the docker files. Just make sure you replace minecraft jar file version inside the code blocks when specified.

obviosly the only difference if your not using Ubuntu is the installation of java and the installation of docker

how to build it

Install all the things

Install Docker Im hesitant to put this step in here because docker changes there crap alot. I recomment just following dockers install steps in the link above. But here is what i did.

sudo apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    software-properties-common

sudo apt-key fingerprint 0EBFCD88

sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"
   
sudo apt-get update && sudo apt-get install docker-ce

Install java. Make sure you pick the lastest stable version.

sudo apt update && sudo apt install openjdk-8-jre

Config of Mincraft Server

Download and run Minecraft Server once manually. This will generate the eula.txt file. Make sure to update the minecraft_server.jar in the command below to your current version.

java -Xmx1024M -Xms1024M -jar minecraft_server<VERSION>.jar nogui

Edit the eula.txt file. Change "eula=false" to "eula=true".

nano eula.txt

Adding minecraft operators

Before moving on i do remmend you grant players operator permissions before building a docker image out of it. becuase its kind annoying to do afterwards.

java -Xmx1024M -Xms1024M -jar minecraft_server<VERSION>.jar nogui

You should see out put like this eventually

[06:12:34] [Server thread/INFO]: Starting minecraft server version 1.12.2
[06:12:34] [Server thread/INFO]: Loading properties
[06:12:34] [Server thread/INFO]: Default game type: SURVIVAL
[06:12:34] [Server thread/INFO]: Generating keypair
[06:12:35] [Server thread/INFO]: Starting Minecraft server on *:25565
[06:12:35] [Server thread/INFO]: Using epoll channel type
[06:12:35] [Server thread/INFO]: Preparing level "world"
[06:12:35] [Server thread/INFO]: Loaded 488 advancements
[06:12:35] [Server thread/INFO]: Preparing start region for level 0
[06:12:36] [Server thread/INFO]: Preparing spawn area: 0%
[06:12:37] [Server thread/INFO]: Preparing spawn area: 27%
[06:12:38] [Server thread/INFO]: Preparing spawn area: 76%
[06:12:39] [Server thread/INFO]: Done (3.961s)! For help, type "help" or "?"

Then issue the mincraft command

op <Your Players Name>

Configure Docker

Add a Dockerfile in the same directory as the the minecraft server files.

nano Dockerfile

Past this in the Dockerfile. Make sure to update the minecraft_server.jar in the command below to your current version.

FROM java:8
WORKDIR /app/
ADD . /app/
EXPOSE 25565:25565
CMD java -Xmx1024M -Xms1024M -jar minecraft_server<VERSION>.jar nogui

Build Docker image

sudo docker build . --tag minecraft

Create a docker volume so the server data is persistant if the docker containers stops for any reason.

sudo docker volume create minecraftvol

Run your docker image. this will set the mincraft container to auto restart should anthing happen to your Ubuntu server, unless you stop the docker conatiner manually.

sudo docker run -d -p 25565:25565 --restart unless-stopped --mount source=mincraftvol,target=/app minecraft

Ready to Play

you can now connect to the server using the servers ipaddress or Domain name if you have mapped one.

Some Issues I havent quite resolved.

I dont yet know how to attach the mincraft containers java terminal that is already running. This is important becasue it is only though this process that you can grant players the "operators" permissions so players can run cheats and stuff. currently I have to stop the container, then run the container without the '-d' flag to gain access to the java terminal which allows you issue mincraft commands in "god mode".

basic steps

list containers, take note of the Container ID. should be a random string of numbers and letters.

sudo docker container list

Stop the mincraft Container

sudo docker container stop <ContainerID>

To run the Container and get the java terminal.

sudo docker run -p 25565:25565 --mount source=mincraftvol,target=/app minecraft

after your finished with the java terminal

list containers again

sudo docker container list