"No simulation script" debugging

Hi folks,

When I try to run a Gatling script locally, it runs fine. When I run the same script on a Jenkins box in EC2-land, I get this:

jenkins@localhost:~/my_folder$ gatling --simulations-folder .
GATLING_HOME is set to /usr/local/gatling/gatling-charts-highcharts-bundle-3.3.1
There is no simulation script. Please check that your scripts are in user-files/simulations

I suspect this is a JVM error, but I’m not sure. I’d like to debug it to understand why Gatling is unable to find a Scala class that’s manifestly there, but I can’t figure out how to enable verbose logging. I’ve seen various tricks on the Internet for enabling verbose logging of every HTTP request/response, but Gatling doesn’t even get to that point; it fails before it can send any HTTP requests.

I found a trick that should allow me to log, in Logback, every message from any class beginning with io.gatling.*: https://stackoverflow.com/a/48664150/5029503 . I’ve not gotten it to work, but:

  1. Is that the right approach, and
  2. Is there some sort of -v option to Gatling that would get me what I’m looking for?

More generally:

  1. Any pointers on debugging this sort of failure before we’ve even hit the Scala scenario?