Way to use locust.io by supplying user list

Question

I need to stress-test a system and http://locust.io seems like the best way to go about this. However, it looks like it is set up to use the same user every time. I need each spawn to log in as a different user. How do I go about setting that up? Alternatively, is there another system that would be good to use?

Answer 1

Locust author here.

By default, each HttpLocust user instance has an HTTP client that has it's own separate session.

Locust doesn't have any feature for providing a list of user credentials or similar. However, your load testing scripts are just python code, and luckily it's trivial to implement this yourself.

Here's a short example:

# locustfile.py

from locust import HttpLocust, TaskSet, task

USER_CREDENTIALS = [
    ("user1", "password"),
    ("user2", "password"),
    ("user3", "password"),
]

class UserBehaviour(TaskSet):
    def on_start(self):
        if len(USER_CREDENTIALS) > 0:
            user, passw = USER_CREDENTIALS.pop()
            self.client.post("/login", {"username":user, "password":passw})

    @task
    def some_task(self):
        # user should be logged in here (unless the USER_CREDENTIALS ran out)
        self.client.get("/protected/resource")

class User(HttpLocust):
    task_set = UserBehaviour
    min_wait = 5000
    max_wait = 60000

The above code wouldn't work when running Locust distributed, since the same code runs on each slave node, and they don't share any state. Therefore you would have to introduce some external datastore which the slave nodes could use to share states (e.g. PostgreSQL, redis, memcached or something else).