Dr Jskill

Spring Boot skill that follows Julien Dubois' best practices.

Overview

This agent skill helps you create Spring Boot projects following Julien Dubois' best practices. It provides tools and scripts to quickly bootstrap Spring Boot applications using https://start.spring.io.

Recommended model: Dr JSkill works best with GPT-5.5.

Version Management

Centralized versions live in versions.json. All scripts read from it via scripts/lib/versions.mjs (JavaScript). Update this file to bump Java, Spring Boot fallback, Postgres, Node/npm, Testcontainers, etc.

Prerequisites

1. Java 25 installed
2. Node.js 24.x and NPM 11.x (for front-end development)
3. Docker installed and running

Capabilities

• Generate Spring Boot projects with predefined configurations
• Support for various Spring Boot versions and dependencies
• Follow best practices for project structure and configuration
• Quick setup scripts for common use cases
• Docker support for containerized deployments
• Front-end development with multiple framework options:
  • Vue.js 3 (default) - Progressive framework with Composition API
  • React 19 - Popular library for building user interfaces
  • Angular 22 - Full-featured framework with TypeScript
  • Vanilla JavaScript - No framework, pure ES6+ with Vite

Usage

Using the Scripts

This skill includes cross-platform JavaScript (Node.js) scripts in the scripts/ directory that can be used to download pre-configured Spring Boot projects from start.spring.io. They work on Linux, macOS, and Windows.

Unified launcher (cross-platform):

node scripts/create-project my-app com.myco my-app com.myco.myapp 25 fullstack --output-dir /absolute/path/to/user/workspace

Direct invocation:

node scripts/create-project-latest.mjs my-app com.myco my-app com.myco.myapp 25 fullstack --output-dir /absolute/path/to/user/workspace

Flags supported:

• --boot-version <x.y.z> / -BootVersion: override Spring Boot version
• --project-type basic|web|fullstack / -ProjectType
• --output-dir <absolute-path>: create the generated project folder under this directory

Output directory rule (important for Agent Skills): bundled scripts are run from the skill directory root. When the user asks to create an app, pass --output-dir with the user's current working directory from the agent session so the generated project folder is created in the user's workspace, not inside the dr-jskill skill folder. Only omit --output-dir when running Dr JSkill's own tests, where generating inside the skill checkout is intentional.

Tip: The create-project-latest script auto-resolves preferred Boot 4.x and falls back to the configured springBootFallback if 4.x is not yet available. Override with --boot-version if needed.

Latest Version Project ⭐

Use the create-project-latest.mjs script to create a project with the latest Spring Boot version (automatically fetched):

node scripts/create-project-latest.mjs my-app com.mycompany my-app com.mycompany.myapp 25 web

Project types available:

• basic - Minimal Spring Boot project
• web - Web application with REST API capabilities
• fullstack - Complete application with database and security

Basic Spring Boot Project

Use the create-basic-project.mjs script to create a basic Spring Boot project with essential dependencies:

node scripts/create-basic-project.mjs

Web Application

Use the create-web-project.mjs script to create a Spring Boot web application with web dependencies:

node scripts/create-web-project.mjs

Full-Stack Application

Use the create-fullstack-project.mjs script to create a comprehensive Spring Boot application with database, security, and web dependencies:

node scripts/create-fullstack-project.mjs

Best Practices

When creating Spring Boot projects:

1. Use the latest Spring Boot version (currently 4.x) - the create-project-latest.mjs script automatically fetches it
2. Review Spring Boot 4 critical considerations: See Spring Boot 4 Migration Guide for Jackson 3 annotations and TestContainers configuration
3. Include Spring Boot Actuator for production-ready features
4. Use Spring Data JPA for database access
5. Use PostgreSQL for database - see Database Best Practices for optimization
6. Use properties files for configuration - see Configuration Best Practices
7. Set up foundational dotfiles: .gitignore, .env.sample, .editorconfig, .gitattributes, .dockerignore, optional .vscode/, .devcontainer/ - see Project Setup & Dotfiles
   • The .env file is the canonical location for local secrets; instruct users to copy .env.sample → .env and fill in real values
   • NEVER read or expose .env: it contains real secrets — do not cat, view, or print its contents; only .env.sample (placeholder values) may be read or displayed
8. Follow daily Git best practices for small branches, reviewed diffs, safe commits, pull requests, and worktrees - see Git Best Practices
9. Use spring-boot-docker-compose for automatic database startup during development - see Docker Guide
10. Follow RESTful API design principles
11. Configure proper logging with Logback - see Logging Best Practices
12. Use Maven for dependency management
13. Include Spring Boot DevTools for development productivity
14. Add Spring Security only when needed - see Security Guide for best practices
15. Configure Docker for containerized deployments - see Docker Guide
16. Enable GraalVM native image support for faster startup - see GraalVM Guide
17. Always ship a startup banner that prints access URLs when the app is ready - see Startup Banner
18. The user must review changes before they are committed to git. Ask the user before initializing a Git repository, or running git commands.

Java Code Intelligence (JDTLS) ⭐

Generated projects integrate with the Eclipse JDT Language Server (JDTLS) so AI agents can navigate, refactor, and diagnose Java code semantically rather than with text search. The scripts ship a .github/lsp.json that wires JDTLS into GitHub Copilot CLI automatically.

For the AI agent: when working on Java files, prefer the lsp tool over grep/view/sed. It understands imports, generics, inheritance, and Javadoc.

Preference order for Java work: lsp → grep with .java glob → view.

Install JDTLS once: brew install jdtls (or see JDTLS guide for other platforms). Full setup, gotchas, and editor integrations live in references/JDTLS.md.

Project Structure

The service layer is only included if it adds value (e.g. complex business logic). For simple CRUD applications, the controller can directly call the repository.

Generated projects follow the following recommended structure:

my-spring-boot-app/
├── .gitignore                 # Java + front-end + secrets (see references/PROJECT-SETUP.md)
├── .env.sample                # Template for local env vars; .env is gitignored
├── .editorconfig              # Consistent formatting across IDEs
├── .gitattributes             # Normalize line endings, better diffs
├── .dockerignore              # Slim Docker build contexts
├── .vscode/                   # Optional editor recommendations
│   ├── extensions.json
│   └── settings.json
├── .devcontainer/             # Optional Dev Container (Java 25 + Node 24 + PostgreSQL)
│   ├── devcontainer.json
│   └── docker-compose.yml
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/example/app/
│   │   │       ├── Application.java
│   │   │       ├── config/
│   │   │       ├── controller/
│   │   │       ├── service/         # Only included if needed
│   │   │       ├── repository/
│   │   │       └── domain/
│   │   └── resources/
│   │       ├── static/              # Front-end web assets (HTML, CSS, JS)
│   │       │   ├── index.html
│   │       │   ├── css/
│   │       │   │   └── styles.css
│   │       │   ├── js/
│   │       │   │   └── app.js
│   │       │   └── images/
│   │       └── application.properties
│   └── test/
│       └── java/
│           └── com/example/app/
│               ├── config/
│               ├── controller/
│               ├── service/         # Only included if needed
│               ├── repository/
│               └── domain/
├── Dockerfile                   # JVM image (jlink runtime + distroless)
├── Dockerfile-aot               # JVM + Spring AOT image
├── Dockerfile-native            # GraalVM native image
├── Dockerfile-crac              # CRaC (fast-restore) image
├── checkpoint-and-run.sh        # CRaC entrypoint helper
├── compose.yaml                 # Dev database (spring-boot-docker-compose)
├── docker-compose.yml           # Full stack with PostgreSQL (JVM)
├── docker-compose-aot.yml       # Full stack with PostgreSQL (AOT)
├── docker-compose-native.yml    # Full stack with PostgreSQL (native)
├── docker-compose-crac.yml      # CRaC app (database-free)
├── pom.xml
└── README.md

Dependencies

Generated projects include: Spring Web, Spring Data JPA, Spring Boot Actuator, DevTools, PostgreSQL, Validation, Docker Compose support, Test Starter with JUnit 5, and TestContainers.

Configuration

Use .properties files (not YAML), externalize secrets via environment variables, and leverage @ConfigurationProperties for type safety. See the Configuration Guide for profiles, secrets management, and common patterns.

The .env file is the single local secret store — never read or print it; only .env.sample (placeholder values) may be shown.

For database optimization, see the Database Best Practices Guide.

Security (Optional)

Spring Security is optional - only add it when you need authentication or authorization. See the Security Guide for JWT, OAuth2, role-based access, and CORS configuration.

Testing

See the Testing Guide for unit tests (Mockito, @WebMvcTest), integration tests (TestContainers + @ServiceConnection), and Given-When-Then patterns with AssertJ.