Spring Boot

Spring Boot was released in 2014. The idea behind this project was to present a way to deploy the web application outside of any container, such as Apache Tomcat, Jetty, and so on. The benefit of this kind of deployment is the independence from any external service. It allows us to run the web applications with one JAR file. Nowadays, this is an excellent approach because this forms the most natural way to adopt DevOps culture.

Spring Boot provides embedded servlet containers, such as Apache Tomcat, Jetty, and Undertow. It makes the development process more productive and comfortable when testing our web applications. Also, customizations during configuration are allowed via a configuration file, or by providing some beans.

There are some advantages when adopting the Spring Boot framework. The framework does not require any XML for configuration. This is a fantastic thing because we will find all the dependencies in the Java files. This helps the IDEs to assist developers, and it improves the traceability of the code. Another important advantage is that the project tries to keep the configuration as automatic as possible. Some annotations make the magic happen. The interesting thing here is that Spring will inject the implementation of any code that is generated at runtime.

The Spring Boot framework also provides interesting features to help developers and operations, such as health checks, metrics, security, and configuration. This is indispensable for modern applications where the modules are decomposed in a microservices architecture.

There are some other interesting features that can help the developers DevOps-wise. We can use the application-{profile}.properties or application.yaml files to configure different runtime profiles, such as development, testing, and production. It is a really useful Spring Boot feature.

Also, the project has full support for the tests, since the web layer up to the repository layer.

The framework provides a high-level API to work with unit and integration tests. Also, the framework supplies many annotations and helpers classes for developers.

The Spring Boot project is a production-ready framework with default optimized configurations for the web servers, metrics, and monitoring features to help the development team deliver high-quality software.

We can develop applications by coding in the Groovy and Java languages. Both are JVM languages. In version 5.0, the Spring Team announced the full support for Kotlin, the new language for JVM. It enables us to develop consistent and readable codes. We will look at this feature in depth in Chapter 7, Airline Ticket System.