Debugging

Logback

There’s a logback.xml file in the Gatling conf directory. You can either set the log-level to TRACE to log all HTTP requests and responses or DEBUG to log failed HTTP request and responses.

<!-- uncomment and set to DEBUG to log all failing HTTP requests -->
<!-- uncomment and set to TRACE to log all HTTP requests -->
<!--<logger name="io.gatling.http.engine.response" level="TRACE" />-->

It will by default print debugging information to the console, but you can add a file appender,

<appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>PATH_TO_LOG_FILE</file>
    <append>true</append>
    <encoder>
        <pattern>%d{HH:mm:ss.SSS} [%-5level] %logger{15} - %msg%n%rEx</pattern>
    </encoder>
</appender>

And reference that appender

<root level="WARN">
    <appender-ref ref="FILE" />
</root>

This can be useful if you run at one user and remove all logging apart from the HTML, and open the file in your browser.