AWS lambda/python3.11 image size

Question

I am creating a lambda function based on a docker image following these aws tutorial. I found the image here, specifically public.ecr.aws/lambda/python:3.11

The problem is that in the page is says that the max size of that will be 238 MB, buuut when I build this Dockerfile

FROM public.ecr.aws/lambda/python:3.11
COPY lambda_function.py ${LAMBDA_TASK_ROOT}
CMD [ "lambda_function.handler" ]

with this

docker build -t positions-backend .

and next I run

docker images

I realize that my image is 749MB size

This is my empty lambda function

def handler(event, context):
    return {
        'statusCode': 200,
        'body': {
            "msg": "hi :D"
        }
    }

Why my image is 748MB with an empty project? thanks

Answer 1

I'm not sure where this figure comes from, but if we pull the base image and examine its history, we'll see:

$ docker pull public.ecr.aws/lambda/python:3.11
$ docker history public.ecr.aws/lambda/python:3.11
IMAGE          CREATED        CREATED BY                                      SIZE      COMMENT
e34e3e59cb88   29 hours ago   ENTRYPOINT [ "/lambda-entrypoint.sh" ]          0B
<missing>      29 hours ago   ENV LAMBDA_RUNTIME_DIR=/var/runtime             0B
<missing>      29 hours ago   ENV LAMBDA_TASK_ROOT=/var/task                  0B
<missing>      29 hours ago   ENV LD_LIBRARY_PATH=/var/lang/lib:/lib64:/us…   0B
<missing>      29 hours ago   ENV PATH=/var/lang/bin:/usr/local/bin:/usr/b…   0B
<missing>      29 hours ago   ENV TZ=:/etc/localtime                          0B
<missing>      29 hours ago   ENV LANG=en_US.UTF-8                            0B
<missing>      29 hours ago   WORKDIR /var/task                               0B
<missing>      29 hours ago   ADD file:384d41d4058f1d590f048a0c1474041c02f…   56.7kB
<missing>      29 hours ago   ADD file:0448654eed630f2f1179287a6e0466928e0…   439MB
<missing>      29 hours ago   ADD file:79a77e7c1be9a2c4f77ead609e8d8b71623…   5.85MB
<missing>      29 hours ago   ADD file:a1bbc10d9f9f6ba22cee5801afc978c0506…   397B
<missing>      29 hours ago   ADD file:178bb853f0ea4e9e47c962179740d55a67f…   627kB
<missing>      29 hours ago   ADD file:c39f5f02ed92d44591fa99789f20fd3aa47…   303MB
<missing>      29 hours ago   ARCHITECTURE amd64                              0B

, which more or less lines up with your observations.

Its largest two layers are 439MB and 303MB in size.