Spring Lessons is a personal reference project built with Spring Boot 4.1.0 and Java 25, designed to explore and consolidate modern enterprise development patterns in a single, runnable application.
The project covers a wide range of topics: REST API design with OAuth2/JWT security via Keycloak, asynchronous event processing with Apache Kafka, relational persistence with JPA and Hibernate, database migration with Flyway, full audit trail via Hibernate Envers, distributed tracing and metrics with OpenTelemetry, and CSV-based bulk import/export. The entire supporting infrastructure (database, broker, identity provider, observability stack) runs locally via Podman Compose.
It serves as a hands-on lab for learning and experimenting with the Spring ecosystem and its integrations.