Technical requirements

In this chapter, we won’t need any additional tools apart from the JDK and the IDE, as in the previous chapters.

Keep in mind that Spring Boot 3.0 requires Java 17 or a later version. To migrate an existing project to Spring Boot 3.0 and use Java 11, you must upgrade to Java 17.

Before migrating to Spring Boot 3.0, I recommend that you upgrade to the latest Spring Boot 2 version, 2.7.x.

In this chapter, we’ll use a Spring Boot 2 sample and make changes to it until it’s finally migrated to the latest version of Spring Boot 3. This application accesses a PostgreSQL database and a Cassandra database. We’ll run both servers using Docker. The official page for running Docker on your computer is https://docs.docker.com/engine/install/. The application has some Testcontainers-based tests, so that you will need Docker on your computer.

To run PostgreSQL on Docker, you can run the following command in your terminal:

docker run...