-Write builder for CurseForge2Discord

-Write container with Openjdk-15

Dockerfile

-FROM lsiobase/alpine:3.12
+FROM openjdk:15-jdk-alpine3.12 AS builder
 
-LABEL maintainer="Griefed <griefed@griefed.de>"
+RUN \
+  apk add --no-cache \
+    git && \
+  git clone \
+    https://github.com/ijo42/CurseForge2Discord.git \
+      /tmp/curseforgebot
+
+WORKDIR /tmp/curseforgebot
+
+RUN \
+  ./gradlew
 
-ARG BOT_VERSION=1.2.3
+FROM lsiobase/ubuntu:bionic
+
+LABEL maintainer="Griefed <griefed@griefed.de>"
 
 RUN \
   echo "**** install dependencies and build tools and stuff ****" && \
-  apk add --no-cache \
-    openjdk8-jre \
-    curl && \
-  echo "**** prepare environment ****" && \
-    mkdir -p \
-      /app/curseforgebot && \
-  echo "**** installing application ****" && \
-    curl -o \
-      /app/curseforgebot/curseforgebot.jar -L \
-        "https://github.com/ErdbeerbaerLP/Curseforge-Bot/releases/download/${BOT_VERSION}/Curseforge-Bot-${BOT_VERSION}.jar" && \
+  curl -o \
+    /tmp/openjdk-15.tar.gz \
+      "https://download.java.net/openjdk/jdk15/ri/openjdk-15+36_linux-x64_bin.tar.gz" && \
+  tar -xf \
+    /tmp/openjdk-15.tar.gz -C \
+       /usr/lib/jvm/ && \
+  mkdir -p \
+    /app/curseforgebot
+
+COPY --from=builder /build/libs/CurseForge2Discord-master.jar /app/curseforgebot/CurseForge2Discord.jar
+
+RUN \
   echo "**** Cleanup ****" && \
     rm -rf \
       /root/.cache \