congiuluc/load-testing-java

Load Testing for Java (Gatling + k6)

When to Use

• Writing load tests co-located with Java projects (Maven/Gradle)
• Testing Spring Boot REST API endpoints under realistic load
• Need rich HTML reports with detailed percentile breakdowns
• Need feeder-based data parameterization for large datasets
• Already using k6 but need supplementary JVM-native tests

Official Documentation

• Gatling Documentation
• Gatling Maven Plugin
• Gatling Gradle Plugin
• k6 Documentation (see load-testing skill)

When to Use Gatling vs k6

| Criteria | Gatling | k6 | |----------|---------|-----| | Language | Java / Scala / Kotlin | JavaScript | | Best for | JVM teams, data-driven | Cross-team, CI/CD gates | | Protocol | HTTP, WebSocket, JMS, MQTT | HTTP, WebSocket, gRPC | | Build integration | Maven/Gradle plugin | CLI / GitHub Action | | Reports | Rich HTML (built-in) | Console, JSON, Prometheus | | Data feeds | CSV, JSON, JDBC, custom | SharedArray, JSON |

Recommendation: Use Gatling for JVM teams that want IDE-integrated, data-driven load tests with rich HTML reports. Use k6 for quick CI/CD pipeline smoke tests.

Procedure

1. Add Gatling dependencies and plugin to build file
2. Follow Gatling patterns
3. Review product simulation sample
4. Design simulations with feeders, checks, and assertions
5. Run locally: mvn gatling:test or gradle gatlingRun
6. For CI/CD pipeline integration, use k6 (see load-testing skill)
7. Analyze HTML report in target/gatling/ or build/reports/gatling/

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>io.gatling.highcharts</groupId>
        <artifactId>gatling-charts-highcharts</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>io.gatling</groupId>
        <artifactId>gatling-test-framework</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>io.gatling</groupId>
            <artifactId>gatling-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Gradle Dependencies

plugins {
    id 'io.gatling.gradle' version '3.12.0'
}

dependencies {
    gatling 'io.gatling.highcharts:gatling-charts-highcharts'
}

Project Structure

src/
  gatling/
    java/
      simulations/
        ProductSimulation.java    # Product API simulation
        AuthSimulation.java       # Auth flow simulation
    resources/
      feeders/
        products.csv              # Test data
      gatling.conf                # Gatling configuration
      logback-test.xml            # Logging config