If you like late night debugging and the smell of stack traces, you will love this guide. This article walks through building production ready Spring Boot REST APIs with sensible architecture, less accidental complexity, and a soothing amount of automated tests. Technical facts intact, snark included.

Project setup and dependencies

Start with Spring Initializr or a standard Maven setup and add the essentials. You want Spring Web and Spring Data JPA for the HTTP and persistence plumbing, Lombok if you enjoy less boilerplate, Spring Security for the part where you stop pretending every endpoint is public, and H2 or PostgreSQL depending on whether you like in memory miracles or long term data grudges.

• Spring Web
• Spring Data JPA
• Lombok
• Spring Security
• H2 or PostgreSQL

Dependency management will save you many hours of crying later, and will also stop your CI from learning creative new failure modes.

Domain model and data access

Design your JPA entities with meaningful relationships and indexes. That means use proper @OneToMany and @ManyToOne where they make sense, add indexes on query heavy columns, and keep lazy loading in mind unless you enjoy surprise N plus one problems.

Create Spring Data repositories to keep CRUD trivial and queries readable. Prefer method names and @Query only when it improves clarity, not to show off your JPQL acrobatics.

DTOs and mapping

Do not expose entities directly. DTOs decouple your API from the database schema and make versioning less painful. Map between entities and DTOs in the service layer or with a mapper library. The goal is clean input validation and predictable output, not subtle coupling that haunts future you.

Service layer and business logic

Put business rules in services to keep controllers thin and boring. Mark transactional boundaries clearly and throw well typed exceptions when rules are violated. Services reduce duplication and make unit testing realistic instead of mythical.

• Encapsulate business logic in @Service beans
• Keep transactions focused and short lived
• Throw domain specific exceptions for clear error mapping

Controllers and request handling

Design REST controllers that accept DTOs and return DTOs. Use validation annotations and spring validation to reject bad input early. Map endpoints with @RequestMapping or the more specific @GetMapping and friends, and return proper HTTP status codes so clients do not have to guess what happened.

Examples will look familiar in every Spring Boot project. Use @Valid on incoming DTOs and convert domain exceptions into clean responses with a central handler.

Validation error handling and testing

Centralize exception handling in a @ControllerAdvice so clients receive consistent API error objects instead of stack traces and cryptic messages. Convert validation errors into useful fields so front end developers stop inventing new curse words.

Write unit tests for services and controllers. Add integration tests with MockMvc or TestRestTemplate so the application behaves as expected when wired together. Tests catch regressions early and keep your CI from staging a mutiny.

• Unit test services and edge cases
• Use MockMvc for controller level integration testing
• Use TestRestTemplate for full stack integration checks

Security and deployment

Protect endpoints with Spring Security. Choose JWT for stateless APIs or session based auth when sessions fit your needs. Configure CORS and role based authorization so only the right people can do the wrong things.

When it is time to ship, package your app as a runnable jar or build a Docker image and deploy to your cloud of choice or the humble VM the team already ignores. Include health checks, sensible logging, and readiness probes so the runtime behaves like a responsible adult.

Final checklist

• Project scaffolded with necessary dependencies
• Entities and repositories modeled with indexes
• DTOs used for API boundaries and clear validation
• Service layer with transactions and typed exceptions
• Controllers with validation and correct status codes
• Centralized exception handling with @ControllerAdvice
• Unit tests and integration tests with MockMvc or TestRestTemplate
• Spring Security configured and app packaged for deployment

If you follow these steps you will end up with maintainable Spring Boot REST APIs that do what they are meant to do, and with fewer surprises at 3 a.m. Now go write code and try not to break production. If you do, at least have good logs.