Initial commit.

Dockerfile

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+
+# Using Ubuntu because it's the most popular, which typically makes
+# troubleshooting easier
+FROM ubuntu:22.04
+
+WORKDIR /minecraft-server
+
+# Install dependencies
+COPY packages-ubuntu.txt .
+RUN apt-get update     \
+ && apt-get upgrade -y \
+ && apt-get install -y $(cat packages-ubuntu.txt)
+
+COPY get-papermc.sh .
+RUN ./get-papermc.sh
+
+# lightweight profiler
+COPY get-spark.sh .
+RUN ./get-spark.sh
+
+COPY entrypoint.sh .
+
+RUN groupadd -r mcserver            \
+ && useradd -r -g mcserver mcserver \
+ && chown mcserver:mcserver --recursive /minecraft-server
+
+USER mcserver:mcserver
+
+ENTRYPOINT ["./entrypoint.sh"]
+
+EXPOSE 25565/tcp
+EXPOSE 25565/udp

entrypoint.sh

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+#!/bin/bash
+
+set -eu
+
+memory_heuristic () {
+	if [[ -v memory_heuristic_cache ]]; then
+		echo $memory_heuristic_cache
+		return
+	fi
+
+	local total_memory=$(free | awk  '/Mem:/{print $2}')
+
+	# Below 8 GB we assume this is running on a dedicated server, so we
+	# allocate all but 10mb of the RAM. Otherwise allocate 30%. This is not
+	# based on any profiling or testing
+	if [[ total_memory -lt 8388608 ]]; then
+		memory_heuristic_cache=$((total_memory - 10240))
+	else
+		memory_heuristic_cache=$((total_memory * 3/10))
+	fi
+
+	memory_heuristic_cache+=k
+
+	echo $memory_heuristic_cache
+}
+
+# https://docs.papermc.io/paper/aikars-flags
+args=()
+args+=("-Xms$(memory_heuristic)")
+args+=("-Xmx$(memory_heuristic)")
+args+=("-XX:+UnlockExperimentalVMOptions")
+args+=("-XX:+ParallelRefProcEnabled")
+args+=("-XX:+DisableExplicitGC")
+args+=("-XX:+AlwaysPreTouch")
+args+=("-XX:+PerfDisableSharedMem")
+args+=("-XX:MaxGCPauseMillis=200")
+args+=("-XX:InitiatingHeapOccupancyPercent=15")
+args+=("-XX:SurvivorRatio=32")
+args+=("-XX:MaxTenuringThreshold=1")
+# G1 options
+args+=("-XX:+UseG1GC")
+args+=("-XX:G1NewSizePercent=30")
+args+=("-XX:G1MaxNewSizePercent=40")
+args+=("-XX:G1HeapRegionSize=8M")
+args+=("-XX:G1ReservePercent=20")
+args+=("-XX:G1HeapWastePercent=5")
+args+=("-XX:G1MixedGCCountTarget=4")
+args+=("-XX:G1MixedGCLiveThresholdPercent=90")
+args+=("-XX:G1RSetUpdatingPauseTimePercent=5")
+mkdir -p logs
+args+=("-Xlog:gc*:logs/gc.log:time,uptime:filecount=5,filesize=1M")
+args+=("-Dcom.mojang.eula.agree=true")
+
+args+=("-jar" "paper.jar" "--nogui")
+
+exec java ${args[@]}

get-papermc.sh

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+#!/bin/bash
+
+set -eu
+
+# print msg to stderr
+debug_msg () {
+	echo "$@" >/dev/stderr
+}
+
+# get the download url for the latest version
+latest_url() {
+	if [[ -v latest_url_cache ]]; then
+		echo $latest_url_cache
+		return
+	fi
+	debug_msg "finding download url to latest version..."
+
+	local url=https://papermc.io/api/v2/projects/paper
+
+	local minecraft_version=$(curl --silent "$url" | jq -r '.versions[-1]')
+	url+=/versions/$minecraft_version
+
+	local papermc_build=$(curl --silent $url | jq -r '.builds[-1]')
+	url+=/builds/$papermc_build
+
+	latest_url_cache=$url/downloads/paper-$minecraft_version-$papermc_build.jar
+	debug_msg "Found url" $latest_url_cache
+	echo $latest_url_cache
+}
+
+debug_msg "downloading..."
+curl --silent $(latest_url) > paper.jar
+
+

get-spark.sh

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+#!/bin/bash
+
+set -eu
+
+# print msg to stderr
+debug_msg () {
+	echo "$@" >/dev/stderr
+}
+
+if ! [[ -d plugins ]]; then
+	debug_msg Creating directory \'plugins\'...
+	mkdir plugins
+fi
+
+cd plugins
+
+debug_msg downloading spark...
+curl --silent \
+	https://ci.lucko.me/job/spark/400/artifact/spark-bukkit/build/libs/spark-*-bukkit.jar/*zip*/libs.zip \
+	    > spark.zip
+
+debug_msg unzipping...
+unzip -oq spark.zip # -o is not 'output', but 'overwrite'. -q is quiet
+
+debug_msg deleting zip...
+rm spark.zip

packages-ubuntu.txt

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+openjdk-21-jre-headless
+curl
+jq
+bash
+unzip