Java Gradle Spring Boot Demo

A production-ready Spring Boot application demonstrating best practices for containerized Java applications with comprehensive test coverage.

Technology Stack

• Java 17 - LTS version with modern language features
• Spring Boot 3.5.6 - Latest Spring Boot framework
• Gradle 8 - Dependency management and build automation
• JUnit 5 - Modern testing framework
• JaCoCo 0.8.12 - Code coverage analysis with 80% minimum threshold
• Checkstyle 10.20.2 - KubeRocketCI standard (4-space indentation)
• Docker - Alpine-based containerization with optimized JRE image

Architecture Approach

Containerization

• Multi-stage Docker build with Eclipse Temurin JRE 17
• Security hardened - runs as non-root user (nobody:nogroup)
• Optimized startup - uses exec for proper signal handling (PID 1)
• Runtime configuration - JVM options via $JAVA_OPTS environment variable

Testing Strategy

• Unit tests with @WebMvcTest for controller layer
• Integration tests with @SpringBootTest for application context
• Coverage enforcement - JaCoCo checks minimum 80% code coverage
• Excludes - Application main class excluded from coverage metrics

Code Quality

• Automated test execution during Gradle build lifecycle
• Coverage reports - HTML, XML, and CSV formats
• Checkstyle with KubeRocketCI standards (4-space indentation)
• CI/CD ready - Fail-fast on coverage violations

Quick Start

Build and Run

# Build the application
./gradlew clean build

# Run tests with coverage
./gradlew test jacocoTestReport

# Run with coverage check
./gradlew check

# Run checkstyle
./gradlew checkstyleMain checkstyleTest

# Run the application from build
java -jar build/libs/*.jar

# Run the application
./gradlew bootRun

Docker

# Build image
docker build -t java-gradle-springboot:latest .

# Run container
docker run -p 8080:8080 \
  -e JAVA_OPTS="-Xmx512m -Xms256m" \
  java-gradle-springboot:latest

API Endpoints

• GET /api/hello - Returns greeting message

Test Coverage

View coverage reports after running tests:

open build/reports/jacoco/test/html/index.html

Current coverage: 100% of application code

Code Quality Reports

View checkstyle reports:

open build/reports/checkstyle/main.html
open build/reports/checkstyle/test.html

Coding Standards:

• 4-space indentation
• Static imports before regular imports
• Line length max 120 characters
• Full Checkstyle compliance (0 violations)

Learn More

This demo is part of the KubeRocketCI platform, which provides a complete CI/CD solution for Kubernetes-native applications.

For comprehensive guides on building cloud-native applications with KubeRocketCI, visit the official documentation.

License

Apache License 2.0