How do I…

Note: Hatch rate/ramp up does not change peak load, it only changes how fast you get there (people keep asking about this for some reason).

Resolve errors that occur during load (error 5xx, Connection aborted, Connection reset by peer, etc)

Check your server logs. If it works at low load then it is almost certainly not a Locust issue, but an issue with the system you are testing.

Clear cookies, to make the next task iteration seem like a new user to my system under test

Call self.client.cookies.clear() at the end of your task.

Control headers or other things about my HTTP requests

Locust’s client in HttpUser inherits from requests and the vast majority of parameters and methods for requests should just work with Locust. Check out the docs and Stack Overflow answers for requests first and then ask on Stack Overflow for additional Locust specific help if necessary.

Create a Locust file based on a recorded browser session

Try using Transformer

How to run a Docker container of Locust in Windows Subsystem for Linux (Windows 10 users)?

If you use WSL on a Windows computer, then you need one extra step than the “docker run …” command: copy your locusttest1.py to a folder in a Windows path on your WSL and mount that folder instead of your normal WSL folder:

$ mkdir /c/Users/[YOUR_Windows_USER]/Documents/Locust/
$ cp ~/path/to/locusttest1.py /c/Users/[YOUR_Windows_USER]/Documents/Locust/
$ docker run -p 8089:8089 -v /c/Users/[YOUR_Windows_USER]/Documents/Locust/:/mnt/locust locustio/locust:1.3.1 -f /mnt/locust/locusttest1.py

How to run locust on custom endpoint

Prefix the the endpoint to all @app.route definitions in locust/web.py file & also change as follows (where /locust is new endpoint)

app = Flask(__name__, static_url_path='/locust')

Change the entries of static content location in file locust/templates/index.html.

Eg: <link rel="shortcut icon" href="{{ url_for('static', filename='img/favicon.ico') }}" type="image/x-icon"/>

Locust web UI doesn’t show my tasks running, says 0 RPS

Locust only knows what you’re doing when you tell it. There are Event Hooks that you use to tell Locust what’s going on in your code. If you use Locust’s HttpUser and then use self.client to make http calls, the proper events are normally fired for you automatically, making less work for you unless you want to override the default events.

If you use the plain User or use HttpUser and you’re not using self.client to make http calls, Locust will not fire events for you. You will have to fire events yourself. See the Locust docs for examples.

HTML Report is filled up with failed requests for long running tests


Other questions and issues

Check the list of issues (a lot of questions/misunderstandings are filed as issues)

Add things that you ran into and solved here! Anyone with a GitHub account can contribute!

If you have questions about Locust that are not answered here, please check StackOverflow, or post your question there. This wiki is not for asking questions but for answering them :)