Accessing performance metrics programatically in Gatling

Question

package computerdatabase

import io.gatling.app.Gatling
import io.gatling.commons.shared.unstable.model.stats.GeneralStats
import io.gatling.core.Predef._
import io.gatling.core.config.GatlingPropertiesBuilder
import io.gatling.http.Predef._

import java.util.concurrent.ThreadLocalRandom

/**
 * This sample is based on our official tutorials:
 *
 *   - [[https://gatling.io/docs/gatling/tutorials/quickstart Gatling quickstart tutorial]]
 *   - [[https://gatling.io/docs/gatling/tutorials/advanced Gatling advanced tutorial]]
 */
class ComputerDatabaseSimulation extends Simulation {
  var simulationId: Option[String] = None

  val feeder = csv("search.csv").random

  val search =
    exec(
      http("Home")
        .get("/")
    )
      .pause(1)
      .feed(feeder)
      .exec(
        http("Search")
          .get("/computers?f=#{searchCriterion}")
          .check(
            css("a:contains('#{searchComputerName}')", "href").saveAs("computerUrl")
          )
      )
      .pause(1)
      .exec(
        http("Select")
          .get("#{computerUrl}")
          .check(status.is(200))
      )
      .pause(1)

  // repeat is a loop resolved at RUNTIME
  val browse =
    // Note how we force the counter name, so we can reuse it
    repeat(4, "i") {
      exec(
        http("Page #{i}").get("/computers?p=#{i}")
      ).pause(1)
    }

  // Note we should be using a feeder here
  // let's demonstrate how we can retry: let's make the request fail randomly and retry a given
  // number of times

  val edit =
    // let's try at max 2 times
    tryMax(2) {
      exec(
        http("Form")
          .get("/computers/new")
      )
        .pause(1)
        .exec(
          http("Post")
            .post("/computers")
            .formParam("name", "Beautiful Computer")
            .formParam("introduced", "2012-05-30")
            .formParam("discontinued", "")
            .formParam("company", "37")
            .check(
              status.is { session =>
                  // we do a check on a condition that's been customized with
                  // a lambda. It will be evaluated every time a user executes
                  // the request
                  200 + ThreadLocalRandom.current().nextInt(2)
              }
            )
        )
    }
    // if the chain didn't finally succeed, have the user exit the whole scenario
    .exitHereIfFailed

  val httpProtocol =
    http.baseUrl("https://computer-database.gatling.io")
      .acceptHeader("text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8")
      .acceptLanguageHeader("en-US,en;q=0.5")
      .acceptEncodingHeader("gzip, deflate")
      .userAgentHeader(
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/119.0"
      )

  val users = scenario("Users").exec(search, browse)
  val admins = scenario("Admins").exec(search, browse, edit)

  setUp(
    users.inject(rampUsers(10).during(10)),
    admins.inject(rampUsers(2).during(10))
  ).protocols(httpProtocol)
  


  
}

Hi everyone! I am using gatling's scala implementation to performance test my applications. I have looked up gatling's documentation and couldn't find anything that could help me in accessing performance metrics programatically. There are few work-arround that i have done and tried like reading performance reports generated by gatling but that doesnt work efficiently. Is there any way that i can access the metrics in my code.

Answer 1

You can't do that with Gatling open-source. The Simulation doesn't have access to the StatsEngine.

However, that's something you could achieve with Gatling Enterprise where the stats can be fetched from a REST API.