Gatling

Introduction#

Gatling is a powerful, open-source load-testing tool designed to analyze and measure the performance of web applications. It uses a simple and expressive domain-specific language (DSL) that allows you to define complex load-testing scenarios with ease.

Performance testing is a crucial aspect of ensuring that applications can handle a large number of users and requests without faltering.

Simulation#

Create a new Kotlin file in the test ?? directory of your project.

Extend the Simulation class#

Gatling scripts extend Simulation. Add the class declaration:

class BasicSimulation : Simulation() {
}

Define the HTTP protocol#

Configure the target base URL and headers so Gatling knows how to talk to your application:

class BasicSimulation : Simulation() {

    // Define HTTP configuration
    // Reference: https://docs.gatling.io/reference/script/http/protocol/
    val protocol = http
        .baseUrl("http://localhost:8080")
        .acceptHeader("application/json")
}

Key callouts:

• http.baseUrl("http://localhost:8080") sets the server you will exercise.
• Custom headers (user agent, accept) mimic a real browser. Adjust them when testing your own system.

Describe a scenario#

Scenarios encode user journeys. Start with a single request:

class BasicSimulation : Simulation() {
    val protocol = http
        .baseUrl("http://localhost:8080")
        .acceptHeader("application/json")

    // Define scenario
    // Reference: https://docs.gatling.io/concepts/scenario/
    val scenario = scenario("BasicSimulation")
        .exec(http("greeting david").get("/greeting?name=David"))
}

Here you:

• Name the scenario (“BasicSimulation”).
• Issue a GET request against /greeting with a query parameter name=David..
• Leave room to add checks or additional steps later.

Choose an injection profile#

Configure the arrival rate and duration for virtual users:

class BasicSimulation : Simulation() {
    val protocol = http
        .baseUrl("http://localhost:8080")
        .acceptHeader("application/json")

    val scenario = scenario("TestSimulation")
        .exec(http("greeting david").get("/greeting?name=David"))

    // Define injection profile and execute the test
    // Reference:  https://docs.gatling.io/concepts/injection/
    init {
        this.setUp(scenario.injectOpen(constantUsersPerSec(50.0).during(Duration.ofSeconds(15))))
            .protocols(protocol)
    }
}