Auto-configuration

Spring Boot auto-configuration automatically sets up your application based on added jar dependencies, such as configuring an in-memory HSQLDB if present and unconfigured. Opt-in via @EnableAutoConfiguration or @SpringBootApplication annotations on a @Configuration class, adding only one to your primary configuration. This process is non-invasive; defining custom beans like DataSource causes default embedded database support to recede. To diagnose applied auto-configuration, start with the --debug switch, enabling debug logs and printing a conditions report to the console. To disable unwanted classes, use the exclude attribute on annotations or the spring.autoconfigure.exclude property. If a class is absent from the classpath, use the excludeName attribute with its fully qualified name. Both @SpringBootApplication and @EnableAutoConfiguration support these exclusions. Note that while auto-configuration classes are public, only the class name constitutes a public API aspect. Scope: Spring Boot. Reviewed October 4, 2026.