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Async Python Handlers in AWS Lambda

Context

I am creating my first AWS Lambda function in Python from scratch. My function contains async functions, so I declared my handler with the async keyword. But when I deployed and smoke tested in AWS, I received the following error:

{
"errorMessage": "Unable to marshal response: Object of type coroutine is not JSON serializable",
"errorType": "Runtime.MarshalError"
}

Search terms

aws lambda python async handler

Helpful link

https://stackoverflow.com/questions/60455830/can-you-have-an-async-handler-in-lambda-python-3-6

Outcome

Apparently AWS Lambda does not support async handler functions in Python. So you are required to call your asynchronous code from a synchronous handler function using this line of code:

asyncio.get_event_loop().run_until_complete(your_async_handler())

By Paul Shippy

Christian software engineer and homeschooling dad

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