add Dockerfile, docker-compose, dependencies, and documentation

Dockerfile

@@ -0,0 +1,22 @@
+# extract mcrcon
+FROM debian:bookworm-slim AS builder
+
+ADD https://github.com/Tiiffi/mcrcon/releases/download/v0.7.2/mcrcon-0.7.2-linux-x86-64-static.zip /usr/bin/mcrcon.zip
+RUN apt-get update && apt-get install -y unzip 
+
+RUN unzip -j /usr/bin/mcrcon.zip -d /usr/bin/mc-rcon && chmod a+x /usr/bin/mc-rcon/mcrcon
+
+
+# actual image
+FROM eclipse-temurin:21
+
+COPY --from=builder /usr/bin/mc-rcon /usr/bin/mc-rcon
+COPY start-server.sh /usr/bin/start-server.sh
+RUN chmod a+x /usr/bin/start-server.sh
+COPY mcrcon /usr/bin/mcrcon
+RUN chmod a+x /usr/bin/mcrcon
+COPY template/ /defaults/
+
+WORKDIR /minecraft_data
+ENTRYPOINT ["/usr/bin/start-server.sh"]
+

README.md

@@ -0,0 +1,69 @@
+# Minecraft Docker Server
+A docker image and compose build for running and controlling a Minecraft server from inside a Docker container. 
+* Supports any version of Minecraft; you just need a link to the server.jar
+    * tested on 1.21, more to come
+* Server console access via [RCON](https://minecraft.wiki/w/RCON)
+    * uses [Tiiffi/mcrcon](https://github.com/Tiiffi/mcrcon) as a prepackaged RCON client
+* All server files stored in a Docker volume
+* Graceful shutdown handling (SIGTERM / SIGINT)
+
+## Usage
+Requires [Docker](https://docs.docker.com/engine/install/), [Git](https://git-scm.com/install/), and a clone of this repository:
+```sh
+git clone https://gitea.jovan04.com/evan/minecraft-docker && cd minecraft-docker
+```
+
+### Build the Image
+```sh
+docker build -t minecraft_server .
+```
+
+### Run with Docker Compose
+`docker-compose.yml` (included in this repository):
+```sh
+docker compose up -d
+```
+(or `docker-compose` for older versions of Docker Compose)
+
+### First Startup
+On first startup (when the data volume is empty):
+* `server.properties` is created from a template
+* `eula.txt` is generated and automatically accepted
+* A default RCON configuration is written
+* `server.jar` is downloaded from a provided link
+
+On subsequent startups, existing files are reused unchanged and environment variables are unused.
+
+### RCON Access
+Minecraft implements the Remote Console (RCON) protocol, which allows server administrators to remotely execute commands. See more info [here](https://minecraft.wiki/w/RCON) and [here](https://developer.valvesoftware.com/wiki/Source_RCON_Protocol). RCON access is enabled automatically from inside the container. **Do not expose the RCON service to the internet directly!!!** RCON is not encrypted, so exposing this service can give hackers direct access to your server's administrator console.
+
+Log into the container:
+```sh
+docker exec -it minecraft_server bash
+```
+Use the provided wrapper script (located at `/usr/bin/mcrcon`). The script dynamically reads the password from `/minecraft_data/server.properties`. 
+
+Send a single command: 
+```sh
+mcrcon list
+mcrcon stop
+```
+
+For an interactive console (`Ctrl-C` or `Ctrl-D` to quit):
+```sh
+mcrcon
+```
+Use this the same as typing into the actual server console
+
+### Graceful Shutdown Behavior
+When the container receives SIGTERM or SIGINT:
+1. A 10-second warning message is broadcast to the server
+2. All chunks are saved manually
+3. A `stop` command is sent to the Minecraft server
+4. The server shuts down normally
+5. The container waits up to a configurable timeout before force-exiting, in case large worlds take a long time to save or the server hangs
+    * default 120s; configure this by changing the `stop_grace_period` time in `docker-compose.yml`
+
+### Configuration
+All Minecraft configuration is done through `server.properties`. Make any necessary changes before **building the image** to the file in this repository, or manually edit the `server.properties` file in the Minecraft server's Docker volume. More info about Docker volumes can be found [here](https://docs.docker.com/engine/storage/volumes). This container should work fine with a relative path in `docker-compose.yml` instead of a named volume. 
+

docker-compose.yml

@@ -0,0 +1,22 @@
+services:
+  minecraft_server:
+    image: minecraft_server
+    container_name: minecraft_server
+    restart: unless-stopped
+    stop_grace_period: 120s
+    volumes:
+      - data:/minecraft_data
+    ports:
+      - 25565:25565
+    environment:
+      # note: this is only used when initializing a new volume (technically, initializing a new server.properties file)
+      # if you want to change the password to your RCON server, edit it in your existing volume's server.properties file
+      MCRCON_PASS: YourPasswordHere
+      # note: again, this download URL is only used when initializing a new volume
+      # this is where the container will attempt to download a server.jar from
+      SERVER_JAR_DOWNLOAD_URL: https://piston-data.mojang.com/v1/objects/450698d1863ab5180c25d7c804ef0fe6369dd1ba/server.jar
+
+volumes:
+  data:
+    name: minecraft_server_data
+

mcrcon

@@ -0,0 +1,4 @@
+#!/bin/bash
+exec /usr/bin/mc-rcon/mcrcon -p "$(
+  grep '^rcon.password=' /minecraft_data/server.properties | cut -d= -f2-
+)" "$@"

start-server.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+
+# initialize required files for an empty volume
+# server.jar
+if ! test -f /minecraft_data/server.jar; then
+    if [ -z "$SERVER_JAR_DOWNLOAD_URL" ]; then
+        echo "ERROR: SERVER_JAR_DOWNLOAD_URL not set for initial volume creation"
+        exit 1
+    fi
+    wget -O /minecraft_data/server.jar "${SERVER_JAR_DOWNLOAD_URL}"
+fi
+
+# server.properties
+if ! test -f /minecraft_data/server.properties; then
+    if [ -z "$MCRCON_PASS" ]; then
+        echo "ERROR: MCRCON_PASS not set for initial volume creation"
+        exit 1
+    fi
+    cat /defaults/server.properties | sed "s/<password_will_auto_populate>/${MCRCON_PASS}/" | tee /minecraft_data/server.properties
+fi
+
+# eula.txt
+if ! test -f /minecraft_data/eula.txt; then
+    cp /defaults/eula.txt /minecraft_data/eula.txt
+fi
+
+export MCRCON_PASS=$(grep "^rcon.password=" /minecraft_data/server.properties | cut -d '=' -f 2- | head -n 1)
+
+# shutdown process
+function shutdown {
+    echo "stopping Minecraft server..."
+    /usr/bin/mc-rcon/mcrcon -p ${MCRCON_PASS} -w 5 "say Server is restarting!" save-all stop
+    wait $SERVER_PID
+}
+
+trap shutdown SIGTERM SIGINT
+
+java -jar /minecraft_data/server.jar --nogui & 
+SERVER_PID=$!
+
+wait $SERVER_PID
+

template/eula.txt

@@ -0,0 +1 @@
+eula=true

template/server.properties

@@ -0,0 +1,9 @@
+# Template server.properties file that allows remote control of the server
+# see https://minecraft.wiki/w/RCON
+broadcast-rcon-to-ops=true
+enable-rcon=true
+# don't change the next line! initializing a new Docker volume will automatically populate 
+rcon.password=<password_will_auto_populate>
+rcon.port=25575
+# the rest of the settings are automatically generated on server startup
+