1. Where is JRE ? If you haven't worked with Java for a long time and have just returned, you may be surprised to find that no JRE packages are included with Java 17. The reason for that is because Oracle no longer expects the general end user to have a Java runtime installed on their system, hence only JDK is provided (see here ). 2. Does it means that I have to use JDK to dockerise my Spring application ? Well, you obviously can use JDK to dockerise your application. However, as JDK is generally large in size and consumes quite a lot of resources, it is not really a good idea to embed JDK inside your application to run in a microservices environment. There are two better choices to dockerise your Spring applications: Use a pre-built JRE from other providers, e.g., https://hub.docker.com/_/eclipse-temurin Build your own JRE with only the components that you need with jlink and jdeps For the first option, it can be seen that there are some pre-built JRE v...