Firing Event Hooks when running Locust as a library

Question

I am trying to perform load test using Locust library for an API endpoint. Here, i am running Locust as a library instead of using locust command. I am trying to perform global setup and global teardown so that a global state is created initially which is used by all the users and then later cleared on teardown(Eg. Downloading S3 files once and then removing it at end).

There are built-in event hooks to add this functionality like init and quitting which can be used when running the locustfile using locust command. But, I am unable to trigger these events when running it as a library. Based on the Locust's source code, I can check that these events are fired in locust main.py file but it's not called when running as a library.

1. How to add such events when running it as a library? I have tried with the below 2 approaches. Is adding event listener and manually calling event.fire() a correct approach or directly creating and calling custom methods for it instead of using events is a better approach?
2. In general, should init and quitting events be used for setting a global state initially and then clearing at end or test_start and test_stop events can also be used in its place?

Source Code for reference:

Approach - 1 (Using event hooks)

import gevent
from locust import HttpUser, task, between
from locust.env import Environment
from locust.stats import stats_printer, stats_history
from locust.log import setup_logging
from locust import events

setup_logging("INFO", None)

def on_init(environment, **kwargs):
    print("Perform global setup to create a global state")

def on_quit(environment, **kwargs):
    print('Perform global teardown to clear the global state')

events.quitting.add_listener(on_quit)
events.init.add_listener(on_init)

class User(HttpUser):
    wait_time = between(1, 3)
    host = "https://docs.locust.io"

    @tas
    def my_task(self):
        self.client.get("/")

    @task
    def task_404(self):
        self.client.get("/non-existing-path")


# setup Environment and Runner
env = Environment(user_classes=[User], events=events)
runner = env.create_local_runner()

### Fire init event and environment and local runner have been instantiated
env.events.init.fire(environment=env, runner=runner)  # Is it correct approach?
 
# start a WebUI instance
env.create_web_ui("127.0.0.1", 8089)

# start a greenlet that periodically outputs the current stats
gevent.spawn(stats_printer(env.stats))

# start a greenlet that save current stats to history
gevent.spawn(stats_history, env.runner)

# start the test
env.runner.start(1, spawn_rate=10)

# in 5 seconds stop the runner
gevent.spawn_later(5, lambda: env.runner.quit())

# wait for the greenlets
env.runner.greenlet.join()

### Fire quitting event when locust process is exiting
env.events.quitting.fire(environment=env, reverse=True) # Is it correct approach?

# stop the web server for good measures
env.web_ui.stop()

Approach - 2 (Creating custom methods and calling these directly)

import gevent
from locust import HttpUser, task, between
from locust.env import Environment
from locust.stats import stats_printer, stats_history
from locust.log import setup_logging
from locust import events

setup_logging("INFO", None)

class User(HttpUser):
    wait_time = between(1, 3)
    host = "https://docs.locust.io"

    @classmethod
    def perform_global_setup(cls):
        print("Perform global setup to create a global state")

    @classmethod
    def perform_global_teardown(cls):
        print('Perform global teardown to clear the global state')

    @task
    def my_task(self):
        self.client.get("/")

    @task
    def task_404(self):
        self.client.get("/non-existing-path")

# setup Environment and Runner
env = Environment(user_classes=[User])
runner = env.create_local_runner()

### Perform global setup 
for cls in env.user_classes:
    cls.perform_global_setup() # Is it correct approach?

# start a WebUI instance
env.create_web_ui("127.0.0.1", 8089)

# start a greenlet that periodically outputs the current stats
gevent.spawn(stats_printer(env.stats))

# start a greenlet that save current stats to history
gevent.spawn(stats_history, env.runner)

# start the test
env.runner.start(1, spawn_rate=10)

# in 5 seconds stop the runner
gevent.spawn_later(5, lambda: env.runner.quit())

# wait for the greenlets
env.runner.greenlet.join()

### Perform global teardown 
for cls in env.user_classes:
    cls.perform_global_teardown() # Is it correct approach?

# stop the web server for good measures
env.web_ui.stop()

Answer 1

1. Both approaches are fine. Using event hooks makes more sense if you think you might want to run in the normal (not as-a-library) way in the future, but if that is unlikely to happen then choose the approach that feels most natural to you.

2. init/quitting only differ from test_start/stop in a meaningful way when doing multiple runs in gui mode (where test_start/stop may happen multiple times). Use the one that is appropriate for what you are doing in the event handler, there is no other guideline.