Refactor image, Java sourcing, and add entrypoint

- Moved to debian-slim base image to minimize size
- Transitioned to Adoptium APT repos for flexibility in Java versions
- Added an entrypoint script that configures EULA and server settings
- Run server in resumable screen for console access in the container

.gitignore

@@ -0,0 +1,2 @@
+data
+.env

Dockerfile

@@ -1,34 +1,62 @@
-FROM debian:stable
+FROM debian:stable-slim
 
-ENV VERSION=1.20.1
+ARG VERSION=latest
-ENV JVM_OPTS="-Xmx2G -Xms1G"
+ARG JAVA_VERSION=latest
 ENV DEBIAN_FRONTEND=noninteractive
-ARG EULA=false
-
-# Install dependencies
-RUN apt-get update && \
-    apt-get install -y curl default-jre jq && \
-    apt-get clean && \
-    rm -rf /var/lib/apt/lists/*
 
 # Create minecraft user
 RUN groupadd -g 1000 minecraft && \
-    useradd -m -u 1000 -g 1000 -d /home/minecraft minecraft
+    useradd -m -u 1000 -g 1000 -d /app minecraft
 
-# Create directory
+# Install scripting dependencies
-RUN mkdir /app && \
+RUN apt-get update && \
-    chown minecraft:minecraft /app
+    apt-get install -y curl gpg jq screen && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Eclipse Adoptium DEB installer package
+RUN set -ux && \
+  # Download the Eclipse Adoptium GPG key
+  curl -s https://packages.adoptium.net/artifactory/api/gpg/key/public \
+    | gpg --dearmor | tee /etc/apt/trusted.gpg.d/adoptium.gpg > /dev/null && \
+  # Configure the Eclipse Adoptium apt repository
+  VERSION_CODENAME="$(awk -F= '/^VERSION_CODENAME/{print $2}' /etc/os-release)" && \
+  echo "deb https://packages.adoptium.net/artifactory/deb $VERSION_CODENAME main" \
+    | tee /etc/apt/sources.list.d/adoptium.list
+
+# Install Adoptium Temurin (OpenJDK Distribution)
+RUN set -ux && \
+  # Grab latest LTS version if not specified
+  if [ "$JAVA_VERSION" = "latest" ]; then \
+    JAVA_VERSION="$( \
+      curl -s https://api.adoptium.net/v3/info/available_releases \
+        | jq '.most_recent_lts' \
+    )"; \
+  fi && \
+  # Install the Temurin version
+  apt-get update && \
+  apt-get install -y "temurin-${JAVA_VERSION}-jre" && \
+  apt-get clean && \
+  rm -rf /var/lib/apt/lists/*
+
+# Download files and run as user
+USER minecraft
+WORKDIR /app
 
 # Download and verify sha1sum for server.jar
-WORKDIR /app
+RUN set -ux && \
-USER minecraft
+  # Grab latest version if not specified
-RUN set -ux; \
+  if [ "$VERSION" = "latest" ]; then \
+    VERSION="$( \
+      curl -s https://launchermeta.mojang.com/mc/game/version_manifest.json \
+        | jq -r '.latest.release' \
+    )"; \
+  fi && \
   # Get server.jar based on $VERSION
   curl -s https://launchermeta.mojang.com/mc/game/version_manifest.json \
-  | jq -r --arg id "$VERSION" '.versions[] | select(.id == $id) | .url' | xargs curl -s \
+    | jq -r --arg id "$VERSION" '.versions[] | select(.id == $id) | .url' \
-  | jq -r '.downloads.server' | tee "/tmp/dl.json" | jq -r '.url' | xargs curl -s -o server.jar && \
+    | xargs curl -s | jq -r '.downloads.server' | tee "/tmp/dl.json" \
-  java -jar server.jar --initSettings --nogui && \
+    | jq -r '.url' | xargs curl -s -o server.jar && \
-  sed -i "s/^eula=.*\$/eula=$EULA/" eula.txt && \
   # Get SHA1 hash of server.jar and compare
   SHA1="$(sha1sum server.jar | awk '{print $1}')" && \
   EXPECTED="$(jq -r .sha1 /tmp/dl.json)"; rm /tmp/dl.json && \
@@ -37,5 +65,21 @@ RUN set -ux; \
     exit 1; \
   fi
 
+# Generate initial settings
+RUN java -jar server.jar --initSettings --nogui
+
+# Back to root to copy the entrypoint in
+USER root
+WORKDIR /app
+
+# Copy in entrypoint script
+COPY entrypoint.sh /usr/local/bin/entrypoint.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh
+
+# Run app as minecraft user
+USER minecraft
+WORKDIR /app
+
+# Expose port and run entrypoint script
 EXPOSE 25565
-CMD ["java", "-jar", "server.jar", "$JVM_OPTS", "--nogui"]
+ENTRYPOINT ["entrypoint.sh"]

README.md

@@ -1,12 +1,17 @@
 # Minecraft Docker Image
+This Dockerfile sets up a Minecraft server based on the `debian-slim` image.
 
-This Dockerfile sets up a Minecraft server based on Debian stable. WIP.
+By running the following and building this image, you are agreeing to
-
+[Minecraft's EULA](https://www.minecraft.net/en-us/eula):
-To test image creation, run:
 ```
-docker build --build-arg EULA=true -t minecraft . && \
+echo "EULA=true" > .env
-docker run -d --name minecraft --rm minecraft && \
+```
-docker logs -f minecraft
+
+To build and test the image:
+```
+docker compose build
+docker compose up -d
+docker logs -f minecraft-minecraft-1
 ```
 
 ## Copyright and License

docker-compose.yml

@@ -0,0 +1,24 @@
+volumes:
+  minecraft:
+
+services:
+  minecraft:
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        VERSION: ${VERSION:-latest}
+        JAVA_VERSION: ${JAVA_VERSION:-latest}
+    image: ${IMAGE:-minecraft}:${TAG:-latest}
+    ports:
+      - "0.0.0.0:25565:25565"
+    #volumes:
+    #  - minecraft:/app/world
+    environment:
+      EULA: "${EULA:-false}"
+      DEBUG: "${DEBUG:-false}"
+      JVM_OPTS: "-Xms1G -Xmx2G"
+      SETTINGS_gamemode: "${GAMEMODE:-survival}"
+      SETTINGS_hardcore: "${HARDCORE:-false}"
+      SETTINGS_motd: "${MOTD:-A Minecraft Server}"
+      SETTINGS_pvp: "${PVP:-true}"

entrypoint.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+
+# Enable debug mode
+DEBUG="${DEBUG:-false}"
+if [ "$DEBUG" = "true" ]; then
+  echo "[DEBUG] Running entrypoint script at $(which entrypoint.sh)"
+  sleep 0.2
+  set -ux
+fi
+
+# Settings
+FILE="${FILE:-/app/server.properties}"
+EULAFILE="${EULAFILE:-/app/eula.txt}"
+PREFIX="${PREFIX:-SETTINGS_}"
+JVM_OPTS="${JVM_OPTS:--Xms1G -Xmx2G}"
+
+# Set EULA
+sed -i.bak "s/^eula=.*\$/eula=${EULA:-false}/" "$EULAFILE"
+diff --unified=1 "${EULAFILE}.bak" "$EULAFILE"
+rm "${EULAFILE}.bak"
+
+# Update server.properties using env
+while IFS='=' read -r ENVVAR VALUE ; do
+  if echo "$ENVVAR" | grep -q "^${PREFIX}.*$"; then
+    KEY="${ENVVAR#"$PREFIX"}"
+    if ! grep -q "^${KEY}=" "$FILE"; then
+      echo "[WARN]: \"$KEY\" does not exist in $FILE and was not updated"
+    else
+      [ "$DEBUG" = "true" ] && echo "[DEBUG] Updating \"$KEY\" to \"$VALUE\""
+      sed -i.bak "s/^${KEY}=.*/${KEY}=${VALUE}/" "$FILE"
+      diff --unified=1 "${FILE}.bak" "$FILE"
+      rm "${FILE}.bak"
+    fi
+  else
+    [ "$DEBUG" = "true" ] && \
+      echo "[DEBUG] \"$ENVVAR\" doesn't have the prefix \"$PREFIX\""
+  fi
+done < <(env)
+
+# Show server.properties in DEBUG mode
+if [ "$DEBUG" = "true" ]; then
+  echo "[DEBUG] Showing ${FILE}:"
+  cat "$FILE"
+fi
+
+# Pre-create the screen log
+touch screenlog.0
+
+# Run server in screen (without attaching)
+/usr/bin/screen -dmS minecraft -L \
+  bash -c "
+    sleep 0.5
+    [ $DEBUG = true ] && echo '[DEBUG] Starting server'
+    /usr/bin/java $JVM_OPTS -jar server.jar --nogui
+  "
+
+# Tail screen log to container stdout
+[ "$DEBUG" = "true" ] && echo "[DEBUG] Tailing screenlog.0"
+tail -f screenlog.0