Package: invokust
invokustA tool for runningLocustload 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 onAWS Lambdafor ultimate scalability.InstallationInstall via pip:pip3 install invokustExamplesRunning a load test using a locust file:importinvokustsettings=invokust.create_settings(locustfile='locustfile_example.py',host='http://www.iana.org',num_users=1,spawn_rate=1,run_time='3m')loadtest=invokust.LocustLoadTest(settings)loadtest.run()loadtest.stats()"{'requests': {'GET_/': {'request_type': 'GET', 'num_requests': 923, 'min_response_time': 113.54585000000128, 'median_response_time': 120.0, 'avg_response_time': 145.68631223510297, 'max_response_time': 331.89674199999786, 'response_times': {270.0: 2, 120.0: 479, 150.0: 17, 200.0: 83, 210.0: 80, 160.0: 20, 190.0: 55, 220.0: 9, 130.0: 30, 170.0: 22, 230.0: 5, 110.0: 69, 140.0: 19, 180.0: 27, 240.0: 2, 320.0: 3, 330.0: 1}, 'response_time_percentiles': {55: 120.0, 65: 150.0, 75: 190.0, 85: 200.0, 95: 210.0}, 'total_rps': 5.136500841568583, 'total_rpm': 308.190050494115}, 'GET_/about': {'request_type': 'GET', 'num_requests': 308, 'min_response_time': 113.23035299999873, 'median_response_time': 120.0, 'avg_response_time': 146.04534828246747, 'max_response_time': 290.40608500000076, 'response_times': {120.0: 147, 200.0: 36, 190.0: 25, 110.0: 27, 160.0: 12, 150.0: 6, 180.0: 13, 210.0: 12, 170.0: 13, 220.0: 2, 130.0: 8, 140.0: 6, 290.0: 1}, 'response_time_percentiles': {55: 120.0, 65: 160.0, 75: 180.0, 85: 200.0, 95: 200.0}, 'total_rps': 1.7140219492991589, 'total_rpm': 102.84131695794953}}, 'failures':{}, 'num_requests': 1231, 'num_requests_fail': 0, 'start_time': 1608207776.312684, 'end_time': 1608207956.070369}"Running a load test without locust file:importinvokustfromlocustimportHttpUser,between,taskclassWebsiteUser(HttpUser):wait_time=between(1,3)@task()defget_home_page(self):'''Gets /'''self.client.get("/")settings=invokust.create_settings(classes=[WebsiteUser],host='http://www.iana.org',num_users=1,spawn_rate=1,run_time='3m')loadtest=invokust.LocustLoadTest(settings)loadtest.run()loadtest.stats()"{'requests': {'GET_/': {'request_type': 'GET', 'num_requests': 71, 'min_response_time': 138.60819600000696, 'median_response_time': 360.0, 'avg_response_time': 327.0060322394364, 'max_response_time': 603.2539320000012, 'response_times': {590.0: 1, 210.0: 3, 370.0: 2, 230.0: 5, 200.0: 2, 490.0: 2, 420.0: 4, 480.0: 1, 190.0: 5, 180.0: 6, 400.0: 3, 270.0: 1, 260.0: 3, 280.0: 2, 360.0: 4, 470.0: 2, 460.0: 3, 350.0: 1, 250.0: 1, 380.0: 4, 410.0: 2, 140.0: 1, 440.0: 1, 600.0: 1, 390.0: 2, 450.0: 1, 430.0: 3, 290.0: 1, 240.0: 2, 340.0: 1, 220.0: 1}, 'response_time_percentiles': {55: 370.0, 65: 390.0, 75: 420.0, 85: 450.0, 95: 490.0}, 'total_rps': 0.4443058717398536, 'total_rpm': 26.658352304391215}}, 'failures': {'GET_/': {'method': 'GET', 'name': '/', 'error': "ConnectionError(ProtocolError('Connection aborted.',RemoteDisconnected('Remote end closed connection without response')))", 'occurrences': 1}}, 'num_requests': 71, 'num_requests_fail': 1, 'start_time': 1608208114.321394, 'end_time': 1608208276.0525749}"Running Locust on AWS LambdaAWS Lambdais a great tool for load testing as it is very cheap (or free) and highly scalable.There are many load testing tools such asabandwrk. Then there are other cloud based load testing options such asBlazeMeterorLoaderand some more DIY solutions that use AWS Lambda too such asGoadorserverless-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 withLocustthis is possible.Included is an example function for running Locust on AWS Lambda,lambda_locust.py.Creating a Lambda functionThe process for running a locust test on Lambda involvescreating a zip fileof 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-packagesOr if running on a Mac (python packages need to be compiled for 64 bit Linux) you can use docker:docker run -it --volume=$PWD:/temp python:3.7 bash -c "pip install /temp --target=/temp/python-packages"Create the zip file:zip -q -r lambda_locust.zip lambda_locust.py locustfile_example.py python-packagesThen create the Lambda function using using the AWS CLI:aws lambda create-function --function-name lambda_locust --timeout 300 --runtime python3.7 --role arn:aws:iam::9999999999:role/lambda_basic_execution --handler lambda_locust.handler --zip-file fileb://lambda_locust.zipOrTerraformand the examplemain.tffile:terraform apply
...Invoking the functionThe 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 testLOCUST_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 againstLOCUST_NUM_CLIENTS: Number of clients to simulateLOCUST_HATCH_RATE: Number of clients per second to startLOCUST_RUN_TIME: The time the test should run forLOCUST_LOGLEVEL: Level of loggingAWS CLIexample with Locust settings in a payload:aws lambda invoke --function-name lambda_locust --invocation-type RequestResponse --payload '{"locustfile": "locustfile_example.py", "host":"http://www.iana.org", "num_users": "1", "spawn_rate": "1", "run_time":"3m"}' --cli-binary-format raw-in-base64-out 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:importjsonfromboto3.sessionimportSessionfrombotocore.clientimportConfigsession=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_users':'1','spawn_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 testLambda function execution time is limited to a maximum of 15 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 calledLambdaLoadTestthat can manage invoking the function in parallel loops and collecting the statistics.importloggingfrominvokust.aws_lambdaimportLambdaLoadTestlogging.basicConfig(level=logging.INFO)lambda_payload={'locustfile':'locustfile_example.py','host':'https://example.com','num_users':1,'spawn_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()print(load_test.get_summary_stats())The output:INFO:root:
Starting load test...
Function name: lambda_locust
Ramp time: 0s
Threads: 2
Lambda payload: {'locustfile': 'locustfile_example.py', 'host': 'https://example.com', 'num_users': '1', 'spawn_rate': 1, 'run_time': '3m'}
Start ramping down after: 30s
INFO:root:thread started
INFO:root:Invoking lambda...
INFO:root:threads: 1, rpm: 0, time elapsed: 0s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 1, rpm: 0, time elapsed: 3s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:thread started
INFO:root:Invoking lambda...
INFO:root:threads: 2, rpm: 0, time elapsed: 6s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 9s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 12s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 15s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 18s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 21s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 24s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 27s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 30s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:threads: 2, rpm: 0, time elapsed: 33s, total requests from finished threads: 0, request fail ratio: 0, invocation error ratio: 0
INFO:root:Time limit reached. Starting ramp down...
INFO:root:Waiting for all Lambdas to return. This may take up to 3m.
INFO:invokust.aws_lambda.lambda_load_test:Lambda invocation complete. Requests (errors): 1867 (0), execution time: 180066ms, sleeping: 0s
INFO:root:thread finished
INFO:invokust.aws_lambda.lambda_load_test:Lambda invocation complete. Requests (errors): 1884 (0), execution time: 180065ms, sleeping: 0s
INFO:root:thread finished
{'lambda_invocation_count': 2, 'total_lambda_execution_time': 360131, 'requests_total': 3751, '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=15 --locust_users=2
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_users': 2, 'spawn_rate': 10, 'run_time': '15s'}

[2020-06-28 19:58:22,103] pudli/INFO/root: thread started
[2020-06-28 19:58:22,107] pudli/INFO/root: threads: 1, rpm: 0, run_time: 0, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
[2020-06-28 19:58:25,108] pudli/INFO/root: threads: 1, rpm: 0, run_time: 3, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
[2020-06-28 19:58:28,109] pudli/INFO/root: threads: 1, rpm: 0, run_time: 6, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
[2020-06-28 19:58:31,110] pudli/INFO/root: threads: 1, rpm: 0, run_time: 9, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
[2020-06-28 19:58:34,112] pudli/INFO/root: threads: 1, rpm: 0, run_time: 12, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
[2020-06-28 19:58:37,113] pudli/INFO/root: threads: 1, rpm: 0, run_time: 15, requests_total: 0, request_fail_ratio: 0, invocation_error_ratio: 0
[2020-06-28 19:58:39,001] pudli/INFO/invokust.aws_lambda.lambda_load_test: Invocation complete. Requests (errors): 224 (120), execution time: 15066, sleeping: 0
[2020-06-28 19:58:40,116] pudli/INFO/root: threads: 1, rpm: 795, run_time: 18, requests_total: 224, request_fail_ratio: 0.5357142857142857, invocation_error_ratio: 0.0
[2020-06-28 19:58:40,117] pudli/ERROR/root: Error limit reached, invocation error ratio: 0.0, request fail ratio: 0.5357142857142857
[2020-06-28 19:58:40,117] pudli/INFO/root: Waiting for threads to exit...
[2020-06-28 19:58:54,086] pudli/INFO/invokust.aws_lambda.lambda_load_test: Invocation complete. Requests (errors): 242 (131), execution time: 15052, sleeping: 0
[2020-06-28 19:58:54,086] pudli/INFO/root: thread finished
[2020-06-28 19:58:54,142] pudli/INFO/root: Aggregated results: {"requests": {"GET_/": {"median_response_time": 92.0, "total_rps": 7.18569301694931, "avg_response_time": 91.08271769409947, "max_response_time": 114.66264724731445, "min_response_time": 84.4886302947998, "response_times": {"histogram": [85, 45, 4, 6, 7, 47, 11, 0, 0, 10], "bins": [84.0, 86.6, 89.2, 91.8, 94.4, 97.0, 99.6, 102.2, 104.8, 107.4, 110.0]}, "total_rpm": 431.1415810169586, "num_requests": 215}, "POST_/post": {"median_response_time": 150.0, "total_rps": 8.38878329746517, "avg_response_time": 157.73737294831653, "max_response_time": 1087.4686241149902, "min_response_time": 142.15636253356934, "response_times": {"histogram": [247, 0, 0, 1, 2, 0, 0, 0, 0, 1], "bins": [140.0, 236.0, 332.0, 428.0, 524.0, 620.0, 716.0, 812.0, 908.0, 1004.0, 1100.0]}, "total_rpm": 503.32699784791026, "num_requests": 251}}, "failures": {"POST_/post": {"method": "POST", "name": "/post", "error": "HTTPError('404 Client Error: Not Found for url: https://example.com/post',)", "occurrences": 251}}, "num_requests": 466, "num_requests_fail": 251, "total_lambda_execution_time": 30118, "lambda_invocations": 2, "approximate_cost": 6.3008e-05, "request_fail_ratio": 0.5386266094420601, "invocation_error_ratio": 0.0, "locust_settings": {"locustfile": "locustfile_example.py", "host": "https://example.com", "num_users": 2, "spawn_rate": 10, "run_time": "15s"}, "lambda_function_name": "lambda_locust", "threads": 1, "ramp_time": 0, "time_limit": 15}
[2020-06-28 19:58:54,142] pudli/INFO/root: ===========================================================================================================================
[2020-06-28 19:58:54,143] pudli/INFO/root: TYPE    NAME                                                #REQUESTS    MEDIAN   AVERAGE       MIN       MAX  #REQS/SEC
Scratch
[2020-06-28 19:58:54,143] pudli/INFO/root: ===========================================================================================================================
[2020-06-28 19:58:54,143] pudli/INFO/root: GET     /                                                         215      92.0     91.08     84.49    114.66       7.19
[2020-06-28 19:58:54,144] pudli/INFO/root: POST    /post                                                     251     150.0    157.74    142.16   1087.47       8.39
[2020-06-28 19:58:54,144] pudli/INFO/root: Exiting...Occasional errorsERROR :xxxxx-3f19-11e7-a1d1-xxxxxxx Process exited before completing request"SOLUTION: Double the size of the memory for the function.