Optimize position-service Dockerfile (#259)

Signed-off-by: Mathieu Benoit <mathieu-benoit@hotmail.fr>

Author: mathieu-benoit

position-service/Dockerfile

@@ -1,19 +1,10 @@
-# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.245.2/containers/java/.devcontainer/base.Dockerfile
-
-# [Choice] Java version (use -bullseye variants on local arm64/Apple Silicon): 11, 17, 11-bullseye, 17-bullseye, 11-buster, 17-buster
-ARG VARIANT="21"
-FROM mcr.microsoft.com/vscode/devcontainers/java:1-${VARIANT} AS build-stage
-
-# Copy code
-WORKDIR /position-service
+FROM --platform=$BUILDPLATFORM eclipse-temurin:21-jdk AS build-stage
+WORKDIR /app
 COPY . .
-
-# Build code
 RUN ./gradlew build
 
-FROM mcr.microsoft.com/openjdk/jdk:${VARIANT}-ubuntu
+FROM eclipse-temurin:21-jre-alpine
 RUN mkdir /app
-COPY --from=build-stage /position-service/build/libs/*.jar /app/position-service.jar
+COPY --from=build-stage /app/build/libs/*.jar /app/position-service.jar
 EXPOSE 18090
-# ENTRYPOINT ./gradlew bootRun
 ENTRYPOINT ["java","-jar","/app/position-service.jar"]