FROM openjdk:15 EXPOSE 80 # Heroku uses the PORT environment variable, it ignores EXPOSE. # This also allows to specify a custom port when running the container even outside of Heroku. ENV PORT 80 ARG JAR_FILE=build/libs/sw-server.jar COPY ${JAR_FILE} app.jar ENTRYPOINT ["sh", "-c", "java -Dserver.port=$PORT -jar /app.jar"]