Test an AWS lambda locally using custom container image - amazon-web-services

Question

I am trying to test the newly added feature of running / invoking lambda with custom container image, so I am building a very simple image from AWS python:3.8 base image as follows:
FROM public.ecr.aws/lambda/python:3.8
COPY myfunction.py ./
CMD ["myfunction.py"]
And here is myfunction.py
import json
import sys
def lambda_handler(event, context):
print("Hello AWS!")
print("event = {}".format(event))
return {
'statusCode': 200,
}
My question is the following: after my build is done:
docker build --tag custom .
how can I now invoke my lambda, given that I do not expose any web endpoints and assuming I am spinning up my custom container with success, (although the handler= part is a little bit unsettling in terms of whether I have configured the handler appropriately)
▶ docker run -p 9000:8080 -it custom
INFO[0000] exec '/var/runtime/bootstrap' (cwd=/var/task, handler=)
A simple curl of course fails
▶ curl -XGET http://localhost:9000
404 page not found

Answer 1

It turns out I have to invoke this extremely non-intuitive url
curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
However I am still getting this error
WARN[0149] Cannot list external agents error="open /opt/extensions: no such file or directory"
START RequestId: f681b2ca-5e35-499d-a262-dd7bc53912f0 Version: $LATEST
Traceback (most recent call last):andler 'py' missing on module 'myfunction'
END RequestId: f681b2ca-5e35-499d-a262-dd7bc53912f0
REPORT RequestId: f681b2ca-5e35-499d-a262-dd7bc53912f0 Init Duration: 1.08 ms Duration: 248.05 ms Billed Duration: 300 ms Memory Size: 3008 MB Max Memory Used: 3008 MB
edit: Solved by changing the CMD from
CMD ["myfunction.py"]
to
CMD ["myfunction.lambda_handler"]