Performance testing with Gatling – integration with Maven

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Post summary: Code samples and explanation how to create performance testing project with Gatling and Maven and run it with Maven plugin.

Current post is part of Performance testing with Gatling series in which Gatling performance testing tool is explained in details.

Code samples are available in GitHub sample-performance-with-gatling repository.

Add Maven dependencies

The first step is to create Maven project and add corresponding dependencies to pom.xml file. Only needed is to gatling-charts-highcharts in order to be able to have access to Galling libraries:

<dependencies>
	<dependency>
		<groupId>io.gatling.highcharts</groupId>
		<artifactId>gatling-charts-highcharts</artifactId>
		<version>2.0.0</version>
	</dependency>
</dependencies>

In GitHub, code version is configured as property for an easy change.

Add Maven plugins

Once dependency to Gatling is added then plugin references should be added. One is for Scala Maven plugin used for compiling/testing/running/documenting Scala code in Maven. Another plugin is Gatling Maven plugin used for running the performance test scenarios:

<build>
	<plugins>
		<plugin>
			<groupId>net.alchim31.maven</groupId>
			<artifactId>scala-maven-plugin</artifactId>
			<version>3.2.2</version>
		</plugin>
		<plugin>
			<groupId>io.gatling</groupId>
			<artifactId>gatling-maven-plugin</artifactId>
			<version>2.0.0</version>
			<configuration>
				<jvmArgs>
					<jvmArg>-Durl=http://localhost:9000</jvmArg>
					<jvmArg>-DnumberOfUsers=10</jvmArg>
					<jvmArg>-DnumberOfRepetitions=1</jvmArg>
					<jvmArg>-DdurationMinutes=1</jvmArg>
					<jvmArg>-DpauseBetweenRequestsMs=3000</jvmArg>
					<jvmArg>-Ddebug=true</jvmArg>
				</jvmArgs>
			</configuration>
		</plugin>
	</plugins>
</build>

Read configurations from Gatling Maven plugin

In order to make it easy to configure several parameters are being passed as jvmArgs, this makes it very easy to run the tests with different configurations. Those are read in code as Java system property:

val numberOfUsers: Int = System.getProperty("numberOfUsers").toInt
val duration: FiniteDuration = System.getProperty("durationMinutes").toInt.minutes
private val url: String = System.getProperty("url")
private val repeatTimes: Int = System.getProperty("numberOfRepetitions").toInt
private val isDebug = System.getProperty("debug").toBoolean

Gatling Maven plugin defaults

By default Gatling Maven plugin uses following default paths, so they do not need to be explicitly provided:

<configuration>
	<configFolder>src/test/resources</configFolder>
	<dataFolder>src/test/resources/data</dataFolder>
	<resultsFolder>target/gatling/results</resultsFolder>
	<bodiesFolder>src/test/resources/bodies</bodiesFolder>
	<simulationsFolder>src/test/scala</simulationsFolder>
</configuration>

Record simulation

Description how to record simulation can be found in Performance testing with Gatling – record and playback post. Once the simulation is recorded it can be modified and added to Maven project. More details what a recorded simulation consists of can be found in Performance testing with Gatling – recorded simulation explanation post.

Running simulation

Gatling simulations are run with the mvn gatling:execute command. The important part is to provide which is the simulation class to be run. One is to use a configuration in pom.xml, other and more flexible is to give it in mvn command: mvn gatling:execute -Dgatling.simulationClass={FULL_PATH_TO_SIMULATION_CLASS}, example is: mvn gatling:execute -Dgatling.simulationClass=com.automationrhapsody.gatling.simulations.original.ProductSimulation

Change default configuration

Default Gatling configuration can be seen in their GitHub: gatling-defaults.conf. If you need to change those when using Gatling with Maven there are two possible options:

Change with a file

In order to change default configuration with a file, you have to create a file similar to gatling-defaults.conf but name it gatling.conf. Leave in the file only the configuration that you want to change. Below is a file that makes Gatling not to produce any reports.

gatling {
  charting {
    noReports = true
  }
}

This file should be put into configFolder property of gatling-maven-plugin config in pom.xml. By default, this is: src/test/resources, but you can change the default as well.

Change with a system property

You can change some Gatling property for this particular run. This is done by adding Java system property into the run command. For the example above, you need to add -Dgatling.charting.noReports=true and now Gatling will not produce reports for this run. Both file and Java system property can be used, but system property is with higher priority. Note that if you have to provide property from core config node, you have to skip core. It is -Dgatling.simulationClass, not -Dgatling.core.simulationClass.

Conclusion

Usage of Gatling with Maven is very convenient and the proper way to do it. Still recorded simulation should be modified before usage. How to modify in order to make it easier to maintain and how to use advanced Gatling features is shown in next post Performance testing with Gatling – advanced usage.

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