invokust 0.52

A small wrapper for locust to allow running load tests from within Python or on AWS Lambda

invokust

A tool for running Locust load tests from within Python without the need to use the locust command line. This gives more flexibility for automation such as QA/CI/CD tests and also makes it possible to run locust on AWS Lambda for ultimate scalability.

Installation

Install via pip:

pip3 install invokust

Examples

Running a load test using a locust file:

import invokust

settings = invokust.create_settings(
    locustfile='locustfile_example.py',
    host='http://example.com',
    num_clients=1,
    hatch_rate=1,
    run_time='3m'
    )

loadtest = invokust.LocustLoadTest(settings)
loadtest.run()
loadtest.stats()
'{"num_requests_fail": 0, "num_requests": 10, "success": {"/": {"median_response_time": 210, "total_rpm": 48.13724156297892, "request_type": "GET", "min_response_time": 210, "response_times": {"720": 1, "210": 7, "820": 1, "350": 1}, "num_requests": 10, "response_time_percentiles": {"65": 210, "95": 820, "75": 350, "85": 720, "55": 210}, "total_rps": 0.802287359382982, "max_response_time": 824, "avg_response_time": 337.2}}, "locust_host": "http://example.com", "fail": {}, "num_requests_success": 10}'

Running a load test without locust file:

import invokust

from locust import HttpLocust, TaskSet, task

class Task(TaskSet):
    @task()
    def get_home_page(self):
        '''
        Gets /
        '''
        self.client.get("/")

class WebsiteUser(HttpLocust):
    task_set = Task

settings = invokust.create_settings(
    classes=[WebsiteUser],
    host='http://example.com',
    num_clients=1,
    hatch_rate=1,
    run_time='3m'
    )

loadtest = invokust.LocustLoadTest(settings)
loadtest.run()
loadtest.stats()
'{"num_requests_fail": 0, "num_requests": 10, "success": {"/": {"median_response_time": 330, "total_rpm": 40.53552561950598, "request_type": "GET", "min_response_time": 208, "response_times": {"230": 1, "1000": 1, "780": 1, "330": 1, "1100": 1, "210": 3, "790": 1, "670": 1}, "num_requests": 10, "response_time_percentiles": {"65": 780, "95": 1100, "75": 790, "85": 1000, "55": 670}, "total_rps": 0.6755920936584331, "max_response_time": 1111, "avg_response_time": 552.8}}, "locust_host": "http://example.com", "fail": {}, "num_requests_success": 10}'

Running Locust on AWS Lambda

AWS Lambda is a great tool for load testing as it is very cheap (or free) and highly scalable.

There are many load testing tools such as ab and wrk. Then there are other cloud based load testing options such as BlazeMeter or Loader and some more DIY solutions that use AWS Lambda too such as Goad or serverless-artillery. But these all have the same drawback: They are too simplistic. They can perform simple GET or POST requests but can't accurately emulate more complex behaviour. e.g. browsing a website, selecting random items, filling a shopping cart and checking out. But with Locust this is possible.

Included is an example function for running Locust on AWS Lambda, lambda_locust.py.

Creating a Lambda function

The process for running a locust test on Lambda involves creating a zip file of the locust load test, creating a Lambda function and then triggering the function.

Install invokust (and its dependencies) python packages locally:

pip3 install invokust --target=python-packages

Or if running on a Mac (python packages need to be compiled for 64 bit Linux) you can use docker:

docker run -it --volume=$PWD/python-packages:/python-packages python:3.6 bash -c "pip install invokust --target=/python-packages"

Create the zip file:

zip -q -r lambda_locust.zip lambda_locust.py locustfile_example.py python-packages

Then create the Lambda function using using the AWS CLI:

aws lambda create-function --function-name lambda_locust --timeout 300 --runtime python3.6 --role arn:aws:iam::9999999999:role/lambda_basic_execution --handler lambda_locust.handler --zip-file fileb://lambda_locust.zip

Or Terraform and the example main.tf file:

terraform apply
...

Invoking the function

The Locust settings can be passed to the Lambda function or can be set from environment variables. The environment variables are:

• LOCUST_LOCUSTFILE: Locust file to use for the load test
• LOCUST_CLASSES: Names of locust classes to use for the load test (instead of a locustfile). If more than one, separate with comma.
• LOCUST_HOST: The host to run the load test against
• LOCUST_NUM_CLIENTS: Number of clients to simulate
• LOCUST_HATCH_RATE: Number of clients per second to start
• LOCUST_RUN_TIME: The time the test should run for.

AWS CLI example with Locust settings in a payload:

aws lambda invoke --function-name lambda_locust --invocation-type RequestResponse --payload '{"locustfile": "locustfile_example.py", "host":"https://example.com", "num_requests":"20", "num_clients": "1", "hatch_rate": "1", "run_time":"3m"}' output.txt
{
    "StatusCode": 200
}
cat output.txt
"{\"success\": {\"GET_/\": {\"request_type\": \"GET\", \"num_requests\": 20, \"min_response_time\": 86, \"median_response_time\": 93 ...

Python boto3 example:

import json
from boto3.session import Session
from botocore.client import Config

session = Session()
config = Config(connect_timeout=10, read_timeout=310)
client = session.client('lambda', config=config)

lambda_payload = {
    'locustfile': 'locustfile_example.py',
    'host': 'https://example.com',
    'num_clients': '1',
    'hatch_rate': 1,
    'run_time':'3m'
}

response = client.invoke(FunctionName='lambda_locust', Payload=json.dumps(lambda_payload))
json.loads(response['Payload'].read())
'{"success": {"GET_/": {"request_type": "GET", "num_requests": 20, "min_response_time": 87, "median_response_time": 99, "avg_response_time": 97.35 ...

Running a real load test

Lambda function execution time is limited to a maximum of 5 minutes. To run a real load test the function will need to be invoked repeatedly and likely in parallel to generate enough load. To manage this there is a class called LambdaLoadTest that can manage invoking the function in parallel loops and collecting the statistics.

import logging
from invokust.aws_lambda import LambdaLoadTest

logging.basicConfig(level=logging.INFO)

lambda_payload = {
    'locustfile': 'locustfile_example.py',
    'host': 'https://example.com',
    'num_clients': '1',
    'hatch_rate': 1,
    'run_time':'3m'
}

load_test = LambdaLoadTest(
  lambda_function_name='lambda_locust',
  threads=2,
  ramp_time=0,
  time_limit=30,
  lambda_payload=lambda_payload
)

load_test.run()
INFO:root:
Starting load test
Function: lambda_locust
Ramp time: 0
Threads: 2
Lambda payload: {'locustfile': 'locustfile_example.py', 'host': 'https://example.com', 'run_time': '30s', 'num_clients': '1', 'hatch_rate': 1, 'run_time':'3m'}

INFO:root:thread started
INFO:root:threads: 1, rpm: 0, run_time: 0, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
INFO:root:threads: 1, rpm: 0, run_time: 3, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
INFO:root:thread started
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 2982, sleeping: 0
INFO:root:threads: 2, rpm: 368, run_time: 6, requests_total: 20, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 2896, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3023, sleeping: 0
INFO:root:threads: 2, rpm: 770, run_time: 9, requests_total: 60, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3041, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3071, sleeping: 0
INFO:root:threads: 2, rpm: 768, run_time: 12, requests_total: 100, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3031, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 2965, sleeping: 0
INFO:root:threads: 2, rpm: 782, run_time: 15, requests_total: 140, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 2957, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3069, sleeping: 0
INFO:root:threads: 2, rpm: 779, run_time: 18, requests_total: 180, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3015, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3018, sleeping: 0
INFO:root:threads: 2, rpm: 771, run_time: 21, requests_total: 220, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3055, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3015, sleeping: 0
INFO:root:threads: 2, rpm: 771, run_time: 24, requests_total: 260, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3007, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3012, sleeping: 0
INFO:root:threads: 2, rpm: 779, run_time: 27, requests_total: 300, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3029, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3037, sleeping: 0
INFO:root:threads: 2, rpm: 773, run_time: 30, requests_total: 340, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3078, sleeping: 0
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3100, sleeping: 0
INFO:root:threads: 2, rpm: 758, run_time: 33, requests_total: 380, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
INFO:root:Time limit reached
INFO:root:Waiting for threads to exit...
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 2965, sleeping: 0
INFO:root:thread finished
INFO:invokust.aws_lambda.lambda_load_test:Invocation complete. Requests (errors): 20 (0), execution time: 3033, sleeping: 0
INFO:root:thread finished

load_test.get_summary_stats()
{'lambda_invocation_count': 21, 'total_lambda_execution_time': 63399, 'requests_total': 420, 'request_fail_ratio': 0.0, 'invocation_error_ratio': 0.0}

There is also an example CLI tool for running a load test, invokr.py:

$ ./invokr.py --function_name=lambda_locust --locust_file=locustfile_example.py --locust_host=https://example.com --threads=1 --time_limit=30 --locust_requests=20
2017-05-22 20:16:22,432 INFO   MainThread
Starting load test
Function: lambda_locust
Ramp time: 0
Threads: 1
Lambda payload: {'locustfile': 'locustfile_example.py', 'host': 'https://example.com', 'num_requests': 20, 'num_clients': 20, 'hatch_rate': 10, 'run_time':'3m'}

2017-05-22 20:16:22,432 INFO   thread_1    thread started
2017-05-22 20:16:22,436 INFO   MainThread  threads: 1, rpm: 0, run_time: 0, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
2017-05-22 20:16:25,440 INFO   MainThread  threads: 1, rpm: 0, run_time: 3, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
2017-05-22 20:16:27,983 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 5186, sleeping: 0
2017-05-22 20:16:28,446 INFO   MainThread  threads: 1, rpm: 216, run_time: 6, requests_total: 20, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:31,448 INFO   MainThread  threads: 1, rpm: 216, run_time: 9, requests_total: 20, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:32,860 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 4798, sleeping: 0
2017-05-22 20:16:34,453 INFO   MainThread  threads: 1, rpm: 246, run_time: 12, requests_total: 40, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:37,454 INFO   MainThread  threads: 1, rpm: 246, run_time: 15, requests_total: 40, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:38,110 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 5176, sleeping: 0
2017-05-22 20:16:40,458 INFO   MainThread  threads: 1, rpm: 229, run_time: 18, requests_total: 60, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:43,072 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 4882, sleeping: 0
2017-05-22 20:16:43,464 INFO   MainThread  threads: 1, rpm: 242, run_time: 21, requests_total: 80, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:46,466 INFO   MainThread  threads: 1, rpm: 242, run_time: 24, requests_total: 80, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:48,237 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 5041, sleeping: 0
2017-05-22 20:16:49,467 INFO   MainThread  threads: 1, rpm: 232, run_time: 27, requests_total: 100, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:52,468 INFO   MainThread  threads: 1, rpm: 232, run_time: 30, requests_total: 100, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:53,347 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 5041, sleeping: 0
2017-05-22 20:16:55,468 INFO   MainThread  threads: 1, rpm: 235, run_time: 33, requests_total: 120, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:55,468 INFO   MainThread  Time limit reached
2017-05-22 20:16:55,468 INFO   MainThread  Waiting for threads to exit...
2017-05-22 20:16:58,666 INFO   thread_1    Invocation complete. Requests (errors): 20 (0), execution time: 5209, sleeping: 0
2017-05-22 20:16:58,667 INFO   thread_1    thread finished
2017-05-22 20:16:59,484 INFO   MainThread  Load test finished. lambda_invocation_count: 7, total_lambda_execution_time: 35333, requests_total: 140, request_fail_ratio: 0.0, invocation_error_ratio: 0.0
2017-05-22 20:16:59,484 INFO   MainThread  Aggregated results: {'success': {'GET_/': {'median_response_time': 285.7142857142857, 'total_rps': 19.753860147907517, 'avg_response_time': 615.4214285714286, 'max_response_time': 1703, 'min_response_time': 100, 'response_times': {'1100': 6, '1400': 9, '120': 2, '140': 14, '960': 3, '180': 9, '160': 11, '260': 6, '300': 3, '1200': 6, '340': 3, '200': 12, '1700': 2, '220': 9, '1300': 10, '380': 3, '440': 5, '240': 5, '1000': 2, '480': 2, '1600': 2, '1500': 9, '100': 1, '360': 1, '540': 1, '940': 1, '280': 1, '320': 1, '400': 1}, 'total_rpm': 1185.231608874451}}, 'fail': {}, 'num_requests': 140, 'num_requests_fail': 0, 'num_requests_success': 140, 'total_time': 35333, 'invocations': 7, 'approximate_cost': 7.4824e-05}
2017-05-22 20:16:59,484 INFO   MainThread  Exiting...