How to use multiple depth handler in AWS Lambda with container images (python3.9)?

Question

The below one is my application directory. There is lambda_handler function on the main.py file.

.
├── Dockerfile
└── app
    └── src
        └── main.py

The below one is my Dockerfile.

FROM public.ecr.aws/lambda/python:3.9

WORKDIR /app

COPY /app /app

RUN yum -y install gcc libmariadb-dev default-libmysqlclient-dev python-devel mysql-devel
RUN /var/lang/bin/python3.9 -m pip install --upgrade pip
RUN pip install -U poetry
RUN poetry export --only main --without-hashes --format=requirements.txt > requirements.txt
RUN pip install -r requirements.txt -t .

ENV PYTHONPATH="$PYTHONPATH:${LAMBDA_TASK_ROOT}"
WORKDIR ${LAMBDA_TASK_ROOT}/src
ENTRYPOINT ["/lambda-entrypoint.sh"]
CMD ["main.lambda_handler"]

I push my image to ECR with GitHub Actions and use it on Lambda. However, when I trigger the function, it raises module not found error.

{
  "errorMessage": "Unable to import module 'main': No module named 'main'",
  "errorType": "Runtime.ImportModuleError",
  "requestId": "...",
  "stackTrace": []
}

Additionally, I use other packages from src modules like the one below.

from typing import Any

from src.custom import Function

def lambda_handler(event: dict[str, Any], context: Any):
    Function...

How should I write the Dockerfile to work Lambda?

Answer 1

I think you are having problems with the paths in the Dockerfile

FROM public.ecr.aws/lambda/python:3.9
    
COPY app/ ${LAMBDA_TASK_ROOT}

RUN yum -y install gcc libmariadb-dev default-libmysqlclient-dev python-devel mysql-devel
RUN /var/lang/bin/python3.9 -m pip install --upgrade pip
RUN pip install -U poetry
RUN poetry export --only main --without-hashes --format=requirements.txt > requirements.txt
RUN pip install -r requirements.txt -t ${LAMBDA_TASK_ROOT}

ENV PYTHONPATH="$PYTHONPATH:${LAMBDA_TASK_ROOT}"
WORKDIR ${LAMBDA_TASK_ROOT}/src
CMD ["main.lambda_handler"]

I'm not sure about the RUN steps but I think that would solve the not found module "main" issue