A Minimal Spring Boot Service: Endpoints and Configuration

Preamble

Spring Boot is the pragmatic JVM on-ramp: auto-configuration, actuator hooks, and dependency injection without XML-era pain. This month I care about structure—where beans wire, where domain rules stay framework-free—not every annotation in the reference manual.

Composition root

@SpringBootApplication and component scanning form the composition root: bind interfaces to implementations here, keep domain packages ignorant of Spring when feasible. That mirrors pushing Django or FastAPI to the edges in Python services.

Configuration layers

application.yml / profiles separate defaults from environment overrides. Treat secrets as injected config, not literals—same discipline as 12-factor Python deploys.

Testability

@SpringBootTest slices trade integration confidence for speed; pure domain tests stay fast and framework-free (Architecture for Evolvable Services After Polyglot Expansion on layers).

Conclusion

Frameworks belong at the boundary; rules live in the middle. itertools Recipes for Interview-Style Iteration plays with itertools for combinatorial iteration patterns.