Docker Companion

Note, entrypoint must exec java binary in order to handle signals properly and have nice graceful shutdown.

FROM eclipse-temurin:25-jre-alpine-3.23 AS server-build
RUN mkdir /server && apk update && apk add wget
WORKDIR /server
RUN wget -O /installer.jar https://maven.neoforged.net/releases/net/neoforged/neoforge/21.1.217/neoforge-21.1.217-installer.jar
RUN java -jar /installer.jar --installServer
RUN echo "eula=true" > eula.txt

FROM eclipse-temurin:25-jre-alpine-3.23
COPY --from=server-build /server /server

RUN cat <<'EOF' > /server/entrypoint.sh
#/usr/bin/env sh
set -e

USER_ID=${USER_ID:-1000}
GROUP_ID=${GROUP_ID:-1000}
USERNAME=${USERNAME:-appuser}

if ! getent group "$GROUP_ID" >/dev/null 2>&1; then
    addgroup -g "$GROUP_ID" "$USERNAME"
fi

if ! id -u "$USER_ID" >/dev/null 2>&1; then
    adduser -D -u "$USER_ID" -G "$USERNAME" -s /bin/bash "$USERNAME"
fi

echo "$SERVER_JAVA_OPTS" > user_jvm_args.txt
chown -R "$USER_ID":"$GROUP_ID" .
exec su-exec "$USERNAME" sh -c 'exec java @user_jvm_args.txt @libraries/net/neoforged/neoforge/21.1.217/unix_args.txt'
EOF

RUN chmod +x /server/entrypoint.sh
RUN apk add --no-cache su-exec
WORKDIR /server
CMD ["/server/entrypoint.sh"]

services:
  minecraft-server:
    build: ./container
    container_name: minecraft-server
    stdin_open: true
    tty: true
    ports:
      - "25565:25565"
    volumes:
      - ./data/mods:/server/mods
      - ./data/world:/server/world
    environment:
      SERVER_JAVA_OPTS: |2
        -Xms2G
        -Xmx10G
        -XX:+UseZGC
        -XX:+ZGenerational 
        -XX:+AlwaysPreTouch 
        -XX:+UseStringDeduplication
      SERVER_OPERATORS: |2
        op-player-uuid
        another-op-player-uuid
      SERVER_PROPERTIES: |2
        max-players=20
        motd=Welcome to the Minecraft Server!
        online-mode=false
        difficulty=normal
        gamemode=survival
        spawn-monsters=true
        view-distance=10
        white-list=false
        pvp=true
        generate-structures=true
        max-world-size=29999984
        enable-query=false
        enable-rcon=false
        enable-status=false
    restart: unless-stopped