blog-ahmza-com/content/posts/mc-server-on-docker/index.md

---
title: Minecraft Server on Docker ⛏ 🐳
date: 2022-05-24
author: "ahmza"
draft: false
weight:

tags: ["games", "docker"]
description: "Ever wanted to build a Minecraft server in docker !! Start here"
---

## **Introduction**

Minecraft is a great game and better with friends. A dedicated server allows you
to do that[^1].

A Minecraft server does not require a ton of resources to run, but from my
experience the more resources you can throw at it the better when you start to
introduce mods and more players.

I run our server on my main PC. This allows me to leverage the system resources
in my PC 🦾 leaving the [Pi
Cluster](https://blog.ahmza.com/posts/building-a-docker-swarm-with-pis/) system
resources to handle the rest of the stuff in my lab.

## **Prerequisites**

- Docker
- Docker Compose

## **Requirements**[^2]

#### **Minimum (1-5 Players)**

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

#### **Recommended (10-15 Players)**

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

#### **Optimal (20+ Players)**

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

## **Building the Container**

1. **Create a directory in which you will keep the Minecraft server files**

```bash
# Make the folder
mkdir minecraft-server
# Ender the folder
cd minecraft-server
```

2. **Create an environment file to be used by the Docker Container**
   - The _.env_ file allows us to specify variables used in the build process.

```bash
# 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=minecraft_server.<version>.jar # change the version
```

3. **Create the docker-compose.yml file**
   - The _docker-compose.yml_ file specifies the container that we want to build [^3]

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

```yaml
version: "3"

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

volumes:
  server-data:
```

4. **Create the Dockerfile file**

   - The Dockerfile builds the container image.

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

```Dockerfile
FROM eclipse-temurin:17-jre

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**

We’re almost there, just a few steps left !!

The curious among you may have realised when trying to start the container that
it fails with the error below:

```bash
Minecraft Server is starting

Error: Unable to access jarfile server.jar
```

This is because we have not downloaded the server jar file yet, that is
our next step.

1. **Navigate to one of the following sites:**[^4]
   - [Vanilla Minecraft Server](https://www.minecraft.net/en-us/download/server) - instructions found here[^5]
   - [Fabric Mod loader server](https://fabricmc.net/use/server/) - instructions found here [^6]
2. **Create a folder in the Minecraft-server folder called .server-data**

```bash
mkdir .server-data
cd .server-data
```

3. **Download the jar file - This will depend on the option above so read the instructions**
4. **Go back to the root minecraft-server folder**

```bash
cd ..
```

5. **Run the container**
   This will create our eula.txt as well as other files needed.

```bash
docker compose up # use CTRL+C to exit
```

```bash
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**

```bash
# enter the .server-data folder
cd .server-data
# edit eula.txt in a text editor
vim eula.txt
# change `eula=false` to `eula=true`
eula=true
```

7. **While in the .server-data folder make any changes you want**

   - Notable files:
     - **server.properties** - properties like server name, game mode, world type etc…
     - **ops.json** - list of server operators (easier to set ingame)
     - **whitelist.json** - list of players allowed to join the server everyone else rejected access.

8. **Run the container**

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

```bash
# monitor the logs as the server starts. CTRL+C to exit
docker logs minecraft-server --follow
# If you see the bottom line then 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

Well done you have setup a Minecraft server, now go play !!

There is a lot of cool stuff you can do from this point, for example installing
mods or creating scripts to manage the server.

[^1]:
    Hosting your own dedicated server allows you to modify every aspect of the
    server as you see fit. I.E you can modify the server-properties, you can
    implement a whitelist not to mention being able to add any mods you want

[^2]: Requirements Gathered from here [https://minecraft.fandom.com/wiki/Server/Requirements/Dedicated#Unix\_.28Linux.2C_BSD.2C_macOS.29](https://minecraft.fandom.com/wiki/Server/Requirements/Dedicated#Unix_.28Linux.2C_BSD.2C_macOS.29)
[^3]:
    Yaml is very picky 😞 when it comes to formatting so if you encounter any
    errors double check your formatting !!

[^4]:
    I have left Forge out as it is a more involved process plus Fabric is
    better 😜

[^5]:
    Right click the green link that says something like minecraft_server.x.xx.x.jar and copy the link address

    `curl -o server.jar \<link you copied here\>`

[^6]:
    Select the Minecraft version, Fabric Loader Version and the Installer Version of your choice. I tend to go with the latest.

    `Copy the curl command under CLI download`