eb open should open up the locust GUI url which is currently: http://locust-testing.us-east-1.elasticbeanstalk.com/

Locust tests are defined in the locustfile.py file. Whatever tests are defined there will run when you start the test in the GUI above. To change tests you edit this file, commit it locally then eb deploy to deploy the changes up to EB.

The tests run against whatever URL is defined in the TARGET_URL env var. Right now it is pointed at https://api-stage.cf-fb.org

The EB Environment is running in US region and is on a large instance so it should have plenty of resources to simulate heaving testing.