Gatling can be configured and optimized in three ways:

  • with configuration files, located in conf directory
  • with command line options
  • with $JAVA_OPTS environment variable

Configuration files


This file allows you to configure the log level of Gatling. For further information, you should have a look at Logback Documentation.


In order to log requests and responses, uncomment the dedicated loggers in the default logging configuration file.


Gatling configuration is based on the great Typesafe Config library.

Gatling configuration files, such as the default configuration file uses the HOCON format.

Gatling uses a fallback strategy, where:

System properties > gatling.conf > gatling-defaults.conf

In the bundle packaging, gatling.conf is placed in the conf directory. It serves as an easy-to-edit base: all properties are commented and all values are the defaults.

In maven/sbt/gradle projects, it must be placed in the resources.

The name of this file can be overriding from a System property named gatling.conf.file, eg -Dgatling.conf.file=gatling-special.conf.

gatling-defaults.conf is shipped in the gatling-core jar and should not be edited.

If you want to override default values, you have two possibilities:

  • change the value in gatling.conf.
  • set a System property (the name of the property must match HOCON Path)


When editing gatling.conf, don’t forget to remove the leading # that comments the line, otherwise your change will be ineffective.

Command Line Options

Gatling can be started with several options listed below:

Option (short)Option (long)Description
-nr–no-reportsRuns simulation but does not generate reports
-ro <folderName>–reports-only <folderName>Generates the reports for the simulation log file located in <gatling_home>/results/<folderName>
-rf <path>–results-folder <path>Uses <path> as the folder where results are stored
-rsf <path>–resources-folder <path>Uses <path> as the folder where resources are stored
-sf <path>–simulations-folder <path>Uses <path> as the folder where simulations are stored
-bf <path>–binaries-folder <path>Uses <path> as the folder where simulation binaries are stored
-s <className>–simulation <className>Uses <className> as the name of the simulation to be run
-rd <description>–run-description <description>A short <description> of the run to include in the report


Default command line options for JAVA are set in the launch scripts. You can use the JAVA_OPTS var to override those defaults, eg:

~$ JAVA_OPTS="myAdditionalOption" bin/