Spring Boot Microservice Maintainer

This skill helps you maintain and upgrade Spring Boot microservices following production-ready best practices for dependency management, testing, code quality, and build configuration.

What This Skill Does

Guides you through maintaining a Spring Boot microservice project with:

Instructions

When a user asks to maintain, upgrade, or troubleshoot a Spring Boot microservice:

1. **Assess Current Project State**

- Read the project's CLAUDE.md or README.md for project-specific context

- Check pom.xml files (root and module-level) for current versions

- Identify module structure (domain, application, tests, etc.)

- Note Java version and Spring Boot version in use

2. **Understand the Request**

- Dependency upgrade (Spring Boot, libraries, plugins)

- Build issues (compilation, test failures)

- Code quality improvements (ErrorProne, Checkstyle)

- Performance or stability assessment

- Migration guidance (Java version, Spring Boot major version)

3. **Execute Appropriate Actions**

**For Dependency Upgrades:**

- Check compatibility (e.g., Spring Boot 3.x requires Java 17+)

- Update parent POM version properties

- Run module-by-module builds to catch issues early

- Test compilation: `mvn clean compile -pl <module>`

- Test execution: `mvn test -pl <module>`

- Document any breaking changes or required configuration updates

**For Build Issues:**

- Start with domain module (lowest dependency level)

- Progress to application module

- Finally test acceptance-tests and benchmark modules

- Check for reflective access warnings (Java 11+) and provide MAVEN_OPTS fix

- Identify ErrorProne warnings vs. compilation errors

**For Code Quality:**

- Enable ErrorProne: `mvn clean compile -Derrorprone=true`

- Review warnings (UnnecessaryLambda, UnusedVariable, etc.)

- Propose fixes for non-blocking issues

- Update Checkstyle configuration if needed

**For Stability Assessment:**

- Compile all modules

- Run all test suites

- Check dependency health (avoid slow security scans in dev)

- Provide module-by-module status table

4. **Provide Clear Guidance**

- Show exact Maven commands to run

- Explain what each command does

- Highlight blocking vs. non-blocking issues

- Provide environment variable fixes (MAVEN_OPTS for Java 11+)

- Document successful changes in project notes

5. **Best Practices to Follow**

- Test module-by-module before full build

- Keep domain module lean (no Spring dependencies)

- Use centralized Checkstyle config (config/checkstyle.xml pattern)

- Avoid slow security scans in dev builds (OWASP removed pattern)

- Update Java version when upgrading Spring Boot major versions

- Document stability status after major changes

Example Usage

**User:** "Upgrade this Spring Boot project to the latest stable version"

**Response:**

1. Read CLAUDE.md and root pom.xml

2. Check current Spring Boot version (e.g., 2.7.5)

3. Identify target version (e.g., 3.2.12)

4. Note Java version requirement (Spring Boot 3.x requires Java 17+)

5. Update pom.xml properties

6. Test domain module: `mvn clean compile test -pl domain`

7. Test application module: `mvn clean compile test -pl application`

8. Run full build: `mvn clean install`

9. Document changes and any breaking changes encountered

**User:** "Fix ErrorProne reflective access warnings"

**Response:**

1. Identify Java version (11+ triggers warnings)

2. Provide MAVEN_OPTS with --add-opens flags

3. Explain this is non-functional (Java module system compatibility)

4. Show command: `export MAVEN_OPTS="--add-opens=jdk.compiler/..."`

Constraints