Non-HTTP Invocation

You don't need Uvicorn and Starlette to use Smyth. Testing your Lambdas that handle events such as SQS, DynamoDB, etc., is also possible with Smyth. You can achieve this by creating an entrypoint script similar to the one in Custom Entrypoint.

Example

In your etc directory, create a smyth_run.py file.

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import asyncio

from smyth.runner.strategy import round_robin
from smyth.smyth import Smyth

def my_handler(event, context):
    print(event["Records"][0]["body"], context.smyth["process"]["name"])

EVENT_DATA = {
    "Records": [
        {
            "messageId": "19dd0b57-b21e-4ac1-bd88-01bbb068cb78",
            "receiptHandle": "MessageReceiptHandle",
            "body": "Hello from SQS!",
            "attributes": {
                "ApproximateReceiveCount": "1",
                "SentTimestamp": "1523232000000",
                "SenderId": "123456789012",
                "ApproximateFirstReceiveTimestamp": "1523232000001",
            },
            "messageAttributes": {},
            "md5OfBody": "7b270e59b47ff90a553787216d55d91d",
            "eventSource": "aws:sqs",
            "eventSourceARN": "arn:aws:sqs:us-east-1:123456789012:MyQueue",
            "awsRegion": "us-east-1",
        }
    ]
}

smyth = Smyth()

smyth.add_handler(
    name="hello",
    path="/hello",
    lambda_handler_path="smyth_run.my_handler",
    timeout=60,
    concurrency=10,
    strategy_generator=round_robin,
)

async def main():
    handler = smyth.get_handler_for_name("hello")
    await asyncio.gather(
        *[
            smyth.invoke(
                handler=handler,
                event_data=EVENT_DATA,
            )
            for _ in range(20)
        ],
        return_exceptions=True,
    )

if __name__ == "__main__":
    with smyth:
        asyncio.run(main())

Import and Declare the Basics

Import asyncio, smyth, and your Lambda handler function.

import asyncio

from smyth.runner.strategy import round_robin
from smyth.smyth import Smyth

def my_handler(event, context):
    print(event["Records"][0]["body"], context.smyth["process"]["name"])

Create the Event Data

This example comes from sam local generate-event sqs receive-message. Yours might be more complex.

EVENT_DATA = {
    "Records": [
        {
            "messageId": "19dd0b57-b21e-4ac1-bd88-01bbb068cb78",
            "receiptHandle": "MessageReceiptHandle",
            "body": "Hello from SQS!",
            "attributes": {
                "ApproximateReceiveCount": "1",
                "SentTimestamp": "1523232000000",
                "SenderId": "123456789012",
                "ApproximateFirstReceiveTimestamp": "1523232000001",
            },
            "messageAttributes": {},
            "md5OfBody": "7b270e59b47ff90a553787216d55d91d",
            "eventSource": "aws:sqs",
            "eventSourceARN": "arn:aws:sqs:us-east-1:123456789012:MyQueue",
            "awsRegion": "us-east-1",
        }
    ]
}

Instantiate Smyth and Add Handlers

Initialize Smyth and add your handlers.

smyth = Smyth()

smyth.add_handler(
    name="hello",
    path="/hello",
    lambda_handler_path="smyth_run.my_handler",
    timeout=60,
    concurrency=10,
    strategy_generator=round_robin,
)

Prepare the Main Function

This part depends on what you want to achieve. Here we are trying to simulate a bunch of SQS messages quickly triggering a handler.

async def main():
    handler = smyth.get_handler_for_name("hello")
    await asyncio.gather(
        *[
            smyth.invoke(
                handler=handler,
                event_data=EVENT_DATA,
            )
            for _ in range(20)
        ],
        return_exceptions=True,
    )

if __name__ == "__main__":
    with smyth:
        asyncio.run(main())

Run It

python etc/smyth_run.py Hello from SQS! hello:8 Hello from SQS! hello:4 Hello from SQS! hello:5 Hello from SQS! hello:3 Hello from SQS! hello:1 Hello from SQS! hello:2 Hello from SQS! hello:6 Hello from SQS! hello:4 Hello from SQS! hello:3 Hello from SQS! hello:1 Hello from SQS! hello:0 Hello from SQS! hello:5 Hello from SQS! hello:8 Hello from SQS! hello:2 Hello from SQS! hello:0 Hello from SQS! hello:6 Hello from SQS! hello:9 Hello from SQS! hello:9 Hello from SQS! hello:7 Hello from SQS! hello:7