python with docker async def SyntaxError: invalid syntax

I have python app in virtualenv that leverage async function calls

Recently I tried moving my app to docker container, with following Dockerfile:

FROM python:3.7
ENV PYTHONUNBUFFERED 1
ADD . /code
WORKDIR /code
RUN pip install -r requirements.txt
CMD [“python3”, “app.py”]

docker-compose.yml:

version: ‘3’

services:

app:

build: .

volumes:

- .:/code

ports:

- “8080:80”

unfortunately, when trying to run my container with docker-compose up I get following error:

    Starting app_1 … done

Attaching to app_1

app_1  |   File “app.py”, line 31

app_1  |     async def handle_DATA(self, server, session, envelope):

app_1  |             ^

app_1  | SyntaxError: invalid syntax

app_1 exited with code 1

What might be cause of this? As far as I know, from python 3.5 async is built-in in stdlib

#python #docker