Spring Boot - Spring Modulith
Apply Spring Modulith guidelines for Spring Boot modular monoliths.
What is covered in this Skill?
- Spring Modulith BOM and starter dependency selection
- Business-capability package structure for application modules
- ApplicationModules verification and architecture tests
- Named interfaces and explicit allowed dependencies
- Domain events for loose coupling between modules
- @ApplicationModuleTest and Scenario-based module integration tests
- Generated module documentation, actuator exposure, and observability
- Event publication registry choices for reliable domain events
Scope: Apply recommendations based on the reference rules, official Spring Modulith documentation, and good/bad examples.
Constraints
Before applying Spring Modulith changes, ensure the project compiles. After improvements, run full verification including module structure tests.
- MANDATORY: Run
./mvnw compile or mvn compile before applying any change
- PRECONDITION: The project must be a Spring Boot application; for non-Boot Java modularity use architecture or design skills instead
- BASELINE: Align dependency choices with Spring Boot 4.0.x and the Spring Modulith compatibility matrix
- SAFETY: If compilation fails, stop immediately
- VERIFY: Run
./mvnw clean verify or mvn clean verify after applying improvements
- BEFORE APPLYING: Read the reference for detailed rules, good/bad patterns, and official documentation links
When to use this skill
- Add Spring Modulith to a Spring Boot application
- Review Spring Modulith module boundaries
- Improve modular monolith architecture in Spring Boot
- Add @ApplicationModuleTest tests
- Generate Spring Modulith documentation
- Refactor Spring Boot modules with Spring Modulith
Workflow
- Read reference and inspect project structure
Read references/305-frameworks-spring-boot-modulith.md and inspect the Spring Boot version, Maven dependencies, main application package, and current package/module boundaries.
- Model application modules
Identify business-capability modules, public APIs, internal packages, named interfaces, and intentional allowed dependencies.
- Apply framework-aligned changes
Add or refine Spring Modulith dependencies, package annotations, architecture verification tests, domain events, and module tests following the reference patterns.
- Run verification and report results
Execute appropriate build/tests, especially ApplicationModules.verify() and @ApplicationModuleTest coverage, then summarize changes, risks, and follow-up module design work.
Reference
For detailed guidance, examples, and constraints, see [references/305-frameworks-spring-boot-modulith.md](references/305-frameworks-spring-boot-modulith.md).
