Use JRE instead of JDK to reduce image size

Author: morey-tech

kanban-app/Dockerfile

@@ -5,7 +5,7 @@ COPY pom.xml /workspace
 COPY src /workspace/src
 RUN mvn -f pom.xml clean package
 
-FROM openjdk:8-alpine
+FROM openjdk:8-jre-alpine
 COPY --from=build /workspace/target/*.jar app.jar
 EXPOSE 8080
 ENTRYPOINT ["java","-jar","app.jar"]