Spring Boot Project Creator

Spring Boot Project Creator

Overview

Generates a fully configured Spring Boot project from scratch using the Spring Initializr API. The skill walks the user through selecting project parameters, choosing an architecture style (DDD or Layered), configuring data stores, and setting up Docker Compose for local development. The result is a build-ready project with standardized structure, dependency management, and configuration.

When to Use

• Bootstrap a new Spring Boot 3.x or 4.x project with a standard structure.
• Initialize a backend microservice with JPA, SpringDoc OpenAPI, and Docker Compose.
• Scaffold a project following either DDD (Domain-Driven Design) or Layered (Controller/Service/Repository/Model) architecture.
• Set up local development infrastructure with PostgreSQL, Redis, and/or MongoDB via Docker Compose.
• Trigger phrases: "create spring boot project", "new spring boot app", "bootstrap java project", "scaffold spring boot microservice", "initialize spring boot backend", "generate spring boot project".

Prerequisites

Before starting, ensure the following tools are installed:

• Java Development Kit (JDK): Version 17+ (Java 21 recommended for Spring Boot 3.x/4.x)
• Apache Maven: Build tool (Spring Initializr generates Maven projects by default)
• Docker and Docker Compose: For running local infrastructure services
• curl and unzip: For downloading and extracting the project from Spring Initializr

Instructions

Follow these steps to create a new Spring Boot project.

1. Gather Project Configuration

Ask the user for the following project parameters using AskUserQuestion. Provide sensible defaults:

2. Generate Project with Spring Initializr

Use curl to download the project scaffold from start.spring.io.

Base dependencies (always included):

• web — Spring Web MVC
• validation — Jakarta Bean Validation
• data-jpa — Spring Data JPA
• testcontainers — Testcontainers support

Conditional dependencies (based on Docker Services selection):

• PostgreSQL selected → add postgresql
• Redis selected → add data-redis
• MongoDB selected → add data-mongodb

bashCopy code
# Example for Spring Boot 3.4.5 with PostgreSQL only
curl -s https://start.spring.io/starter.zip \
  -d type=maven-project \
  -d language=java \
  -d bootVersion=3.4.5 \
  -d groupId=com.example \
  -d artifactId=demo \
  -d packageName=com.example \
  -d javaVersion=21 \
  -d packaging=jar \
  -d dependencies=web,data-jpa,postgresql,validation,testcontainers \
  -o starter.zip

unzip -o starter.zip -d ./demo
rm starter.zip
cd demo

3. Add Additional Dependencies

Edit pom.xml to add SpringDoc OpenAPI and ArchUnit for architectural testing.

xmlCopy code
<!-- SpringDoc OpenAPI -->
<dependency>
    <groupId>org.springdoc</groupId>
    <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
    <version>2.8.15</version>
</dependency>

<!-- ArchUnit for architecture tests -->
<dependency>
    <groupId>com.tngtech.archunit</groupId>
    <artifactId>archunit-junit5</artifactId>
    <version>1.4.1</version>
    <scope>test</scope>
</dependency>

4. Create Architecture Structure

Based on the user's choice, create the package structure under src/main/java/<packagePath>/.

Option A: Layered Architecture

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src/main/java/com/example/
├── controller/        # REST controllers (@RestController)
├── service/           # Business logic (@Service)
├── repository/        # Data access (@Repository, Spring Data interfaces)
├── model/             # JPA entities (@Entity)
│   └── dto/           # Request/Response DTOs (Java records)
├── config/            # Configuration classes (@Configuration)
└── exception/         # Custom exceptions and @ControllerAdvice

Create placeholder classes for each layer:

• config/OpenApiConfig.java — SpringDoc OpenAPI configuration bean
• exception/GlobalExceptionHandler.java — @RestControllerAdvice with standard error handling
• model/dto/ErrorResponse.java — Standard error response record

Option B: DDD (Domain-Driven Design) Architecture

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src/main/java/com/example/
├── domain/                 # Core domain (framework-free)
│   ├── model/              # Entities, Value Objects, Aggregates
│   ├── repository/         # Repository interfaces (ports)
│   └── exception/          # Domain exceptions
├── application/            # Use cases / Application services
│   ├── service/            # @Service orchestration
│   └── dto/                # Input/Output DTOs (records)
├── infrastructure/         # External adapters
│   ├── persistence/        # JPA entities, Spring Data repos
│   └── config/             # Spring @Configuration
└── presentation/           # REST API layer
    ├── controller/         # @RestController
    └── exception/          # @RestControllerAdvice

Create placeholder classes for each layer:

• infrastructure/config/OpenApiConfig.java — SpringDoc OpenAPI configuration bean
• presentation/exception/GlobalExceptionHandler.java — @RestControllerAdvice with standard error handling
• application/dto/ErrorResponse.java — Standard error response record

5. Configure Application Properties

Create src/main/resources/application.properties with the selected services.

Always include:

propertiesCopy code
# Application
spring.application.name=${artifactId}

# SpringDoc OpenAPI
springdoc.swagger-ui.doc-expansion=none
springdoc.swagger-ui.operations-sorter=alpha
springdoc.swagger-ui.tags-sorter=alpha

If PostgreSQL is selected:

propertiesCopy code
# PostgreSQL / JPA
spring.datasource.driver-class-name=org.postgresql.Driver
spring.datasource.url=jdbc:postgresql://localhost:5432/${POSTGRES_DB:postgres}
spring.datasource.username=${POSTGRES_USER:postgres}
spring.datasource.password=${POSTGRES_PASSWORD:changeme}
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

If Redis is selected:

propertiesCopy code
# Redis
spring.data.redis.host=localhost
spring.data.redis.port=6379
spring.data.redis.password=${REDIS_PASSWORD:changeme}

If MongoDB is selected:

propertiesCopy code
# MongoDB
spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
spring.data.mongodb.authentication-database=admin
spring.data.mongodb.username=${MONGO_USER:root}
spring.data.mongodb.password=${MONGO_PASSWORD:changeme}
spring.data.mongodb.database=${MONGO_DB:test}

6. Set Up Docker Compose

Create docker-compose.yaml at the project root with only the services the user selected.

yamlCopy code
services:
  # Include if PostgreSQL selected
  postgresql:
    image: postgres:17
    ports:
      - "5432:5432"
    environment:
      POSTGRES_USER: ${POSTGRES_USER:-postgres}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-changeme}
      POSTGRES_DB: ${POSTGRES_DB:-postgres}
    volumes:
      - ./postgres_data:/var/lib/postgresql/data

  # Include if Redis selected
  redis:
    image: redis:7
    ports:
      - "6379:6379"
    command: redis-server --requirepass ${REDIS_PASSWORD:-changeme}
    volumes:
      - ./redis_data:/data

  # Include if MongoDB selected
  mongodb:
    image: mongo:8
    ports:
      - "27017:27017"
    environment:
      MONGO_INITDB_ROOT_USERNAME: ${MONGO_USER:-root}
      MONGO_INITDB_ROOT_PASSWORD: ${MONGO_PASSWORD:-changeme}
    volumes:
      - ./mongo_data:/data/db

7. Create .env File for Docker Compose

Create a .env file at the project root with default credentials for local development:

envCopy code
# PostgreSQL
POSTGRES_USER=postgres
POSTGRES_PASSWORD=changeme
POSTGRES_DB=postgres

# Redis
REDIS_PASSWORD=changeme

# MongoDB
MONGO_USER=root
MONGO_PASSWORD=changeme
MONGO_DB=test

Include only the variables for the services the user selected. Docker Compose automatically loads this file.

8. Update .gitignore

Append Docker Compose volume directories and the .env file to .gitignore:

Copy code
# Docker Compose
.env
postgres_data/
redis_data/
mongo_data/

9. Verify the Build

Run the Maven build to confirm the project compiles and tests pass:

bashCopy code
./mvnw clean verify

If the build succeeds, inform the user. If it fails, diagnose and fix the issue before proceeding.

10. Present Summary to User

Display a summary of the created project:

Copy code
Project Created Successfully

  Artifact:      <artifactId>
  Spring Boot:   <version>
  Java:          <javaVersion>
  Architecture:  <DDD | Layered>
  Build Tool:    Maven
  Docker:        <services list>

  Directory:     ./<artifactId>/

  Next Steps:
    1. cd <artifactId>
    2. docker compose up -d
    3. ./mvnw spring-boot:run
    4. Open http://localhost:8080/swagger-ui.html

Architecture Patterns

Layered Architecture

Traditional three-tier architecture with clear separation of concerns:

Best for: Simple CRUD applications, small-to-medium services, teams new to Spring Boot.

DDD Architecture

Domain-Driven Design with hexagonal boundaries:

Best for: Complex business domains, microservices with rich logic, long-lived projects.

Examples

Example 1: Simple REST API with PostgreSQL (Layered)

User request: "Create a Spring Boot project for a REST API with PostgreSQL"

bashCopy code
curl -s https://start.spring.io/starter.zip \
  -d type=maven-project \
  -d bootVersion=3.4.5 \
  -d groupId=com.example \
  -d artifactId=my-api \
  -d packageName=com.example.myapi \
  -d javaVersion=21 \
  -d dependencies=web,data-jpa,postgresql,validation,testcontainers \
  -o starter.zip

Result: Layered project with controller/, service/, repository/, model/ packages, PostgreSQL Docker Compose, and SpringDoc OpenAPI.

Example 2: Microservice with DDD and Multiple Stores

User request: "Bootstrap a Spring Boot 3 microservice with DDD, PostgreSQL and Redis"

bashCopy code
curl -s https://start.spring.io/starter.zip \
  -d type=maven-project \
  -d bootVersion=3.4.5 \
  -d groupId=com.acme \
  -d artifactId=order-service \
  -d packageName=com.acme.order \
  -d javaVersion=21 \
  -d dependencies=web,data-jpa,postgresql,data-redis,validation,testcontainers \
  -o starter.zip

Result: DDD project with domain/, application/, infrastructure/, presentation/ packages, PostgreSQL + Redis Docker Compose, and SpringDoc OpenAPI.

Best Practices

• Always use Spring Initializr for project generation to get the correct dependency management and parent POM.
• Use Java records for DTOs — they are immutable and concise.
• Keep domain layer framework-free in DDD architecture — no Spring annotations in domain/.
• Use environment variables for sensitive configuration in production (database passwords, etc.).
• Pin Docker image versions in docker-compose.yaml to avoid unexpected breaking changes.
• Run ./mvnw clean verify after setup to ensure everything compiles and tests pass.
• Add Testcontainers for integration tests instead of relying on Docker Compose.

Constraints and Warnings

• Spring Initializr requires internet access — this skill cannot work offline.
• Spring Boot 4.x availability depends on the current release cycle — check start.spring.io for latest versions.
• Docker Compose credentials are loaded from .env file (git-ignored) — never commit secrets to version control.
• The spring.jpa.hibernate.ddl-auto=update setting is for development only — use Flyway or Liquibase in production.
• ArchUnit version must be compatible with the JUnit 5 version bundled with Spring Boot.