Summary

In this chapter, we saw how we can use Spring Data to add a persistence layer to the core microservices. We used the core concepts of Spring Data, repositories, and entities to store data in both MongoDB and MySQL. The programming model is similar for a NoSQL database such as MongoDB and a SQL database such as MySQL, even though it’s not fully portable. We also saw how Spring Boot’s annotations, @DataMongoTest and @DataJpaTest, can be used to conveniently set up tests targeted for persistence; this is where a database is started automatically before the test runs, but no other infrastructure that the microservice will need at runtime, for example, a web server such as Netty, is started up. To handle the startup and teardown of databases, we have used Testcontainers, which runs the databases in Docker containers. This results in persistence tests that are easy to set up and that start with minimum overhead.

We have also seen how the persistence layer can be...