new: [minecraft] add charm

minecraft/build/Dockerfile

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+FROM docker.0k.io/alpine:3.18
+
+RUN apk add openjdk17 && \
+    mkdir /var/lib/minecraft
+
+WORKDIR /var/lib/minecraft

minecraft/hooks/init

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+#!/bin/bash
+
+## Init is run on host
+## For now it is run every time the script is launched, but
+## it should be launched only once after build.
+
+## Accessible variables are:
+## - SERVICE_NAME        Name of current service
+## - DOCKER_BASE_IMAGE   Base image from which this service might be built if any
+## - SERVICE_DATASTORE           Location on host of the DATASTORE of this service
+## - SERVICE_CONFIGSTORE         Location on host of the CONFIGSTORE of this service
+
+
+. lib/common
+
+set -e
+
+version=$(options-get version) || exit 1
+
+minecraft:init-binary "$version"
+
+threads=$(options-get threads) || exit 1
+mem=$(options-get mem) || exit 1
+
+minecraft:init-command "$threads" "$mem"

minecraft/lib/common

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+# -*- mode: shell-script -*-
+
+
+MINECRAFT_PATH="$SERVICE_CONFIGSTORE/opt/apps/minecraft"
+MINECRAFT_DATA="/var/lib/minecraft"
+
+minecraft:init-binary() {
+    local version="$1"
+
+    MINECRAFT_BINARY="${MINECRAFT_PATH}/minecraft_server.${version}.jar"
+    if ! [ -f "$MINECRAFT_BINARY" ]; then
+        mkdir -p "${MINECRAFT_PATH}"
+        wget "https://docker.0k.io/downloads/minecraft_server.${version}.jar" \
+             -O "$MINECRAFT_BINARY"
+    fi
+    init-config-add "
+$SERVICE_NAME:
+  volumes:
+    - \"${MINECRAFT_BINARY}:${MINECRAFT_DATA}/server.jar\"
+"
+
+}
+
+
+minecraft:init-command() {
+    local threads="${1:-4}" mem="${2:-2048M}"
+    init-config-add "
+$SERVICE_NAME:
+  command:
+  - java
+  - -Xmx${mem}
+  - -Xms${mem}
+  - -XX:ParallelGCThreads=${threads}
+  - -jar
+  - server.jar
+  - nogui
+"
+    echo "eula=TRUE" > "$SERVICE_DATASTORE/${MINECRAFT_DATA}/eula.txt"
+}

minecraft/metadata.yml

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+description: "Minecraft"
+maintainer: "Valentin Lab <valentin.lab@kalysto.org>"
+
+data-resources:
+  - /var/lib/minecraft
+default-options:
+  version: 1.19.4
+  forge: true
+  threads: 2
+  mem: 2048M
+uses:
+  backup:
+    constraint: recommended
+    auto: pair
+    solves:
+      backup: "Automatic regular backup"
+    default-options:
+      ## First pattern matching wins, no pattern matching includes.
+      ## include-patterns are checked first, then exclude-patterns
+      ## Patterns rules:
+      ##  - ending / for directory
+      ##  - '*' authorized
+      ##  - must start with a '/', will start from $SERVICE_DATASTORE