Micronaut Core Guidelines
Apply Micronaut core guidelines for DI, configuration, HTTP adapters, and operations.
What is covered in this Skill?
- Thin
main with Micronaut.run(Application.class, args)
- Bean scopes: @Singleton, @Prototype; request scope only when justified
- Constructor injection with
jakarta.inject.Inject
- @Factory for third-party or explicit bean construction
- @ConfigurationProperties (grouped settings) vs scattered @Property
- @Requires and environments instead of env branching in domain code
- Thin @Controller types delegating to @Singleton services
- @Scheduled with explicit failure visibility
- @ExecuteOn(TaskExecutors.BLOCKING) (or virtual-thread executors) for blocking I/O off the event loop
- Netty graceful shutdown properties
- AOP interceptors for cross-cutting concerns
Scope: Apply recommendations based on the reference rules and good/bad code examples.
Constraints
Before applying Micronaut changes, ensure the project compiles. If compilation fails, stop immediately. After applying improvements, run full verification.
- MANDATORY: Run
./mvnw compile or mvn compile before applying any change
- PREREQUISITE: Project must compile successfully before applying Micronaut core improvements
- SAFETY: If compilation fails, stop immediately — compilation failure is a blocking condition
- VERIFY: Run
./mvnw clean verify or mvn clean verify after applying improvements
- BEFORE APPLYING: Read the reference for detailed rules, good/bad patterns, and constraints
When to use this skill
- Review Java code for Micronaut application structure and beans
- Apply best practices for Micronaut configuration, @Requires, and factories
- Improve scheduling, shutdown, or threading in Micronaut services
- Review Micronaut dependency injection scopes and factories
- Configure Micronaut @Requires conditions for environments
Workflow
- Read reference and assess project context
Read references/501-frameworks-micronaut-core.md and inspect the current project setup before proposing changes.
- Gather scope and decide target improvements
Identify requested outcomes, constraints, and the minimum safe set of changes to apply.
- Apply framework-aligned changes
Implement or refactor configuration/code following the reference patterns and project conventions.
- Run verification and report results
Execute appropriate build/tests and summarize what changed, what was verified, and any follow-up actions.
Reference
For detailed guidance, examples, and constraints, see references/501-frameworks-micronaut-core.md.