Hot reloading doesn't work inside Docker container

[nleroy917]

I've having issues getting the live reloading to work when running the functions-framework inside a Docker container. I'm trying to set up a development environment using docker-compose. I am using the solution implemented here to be able to call all functions from one endpoint.

This is my Dockerfile:

# use alpine linux with standard python-3.9
FROM python:3.9-alpine

# install necessities and c compilers
RUN apk update && apk upgrade && apk add g++ gcc

# open up port 5000
EXPOSE 5000

# set working directory
WORKDIR /server

# copy files over
COPY requirements.txt /server/requirements.txt

# set env variables
ENV FLASK_ENV development
ENV DEBUG true

# install python dependencies
RUN pip install -r requirements.txt

# spin up gcloud functions server
CMD ["functions-framework", "--target=dispatcher", "--port=5000", "--debug"]

And inside docker-compose.yml I have this:

    # functions server
    functions:
        container_name: functions
        restart: always
        ports:
            - "5000:5000"
        build:
            context: ./
            dockerfile: ./Dockerfile.dev
        volumes:
          - ./spottydata:/server/spottydata
          - ./main.py:/server/main.py
        networks:
          - backend

I specified main.py as a mounted volume so it can see changes made during deployment, but nothing I do to that file triggers a hot reload. I wasn't sure if there were any examples running this in a docker container for development.

Thanks!

[di]

Hi @nleroy917, sorry you're having trouble.

I wasn't sure if there were any examples running this in a docker container for development.

There wasn't, so I added these in #143. With this minimal example, live reloading works as expected for me. Could you try to reproduce with that example and work backwards to your current setup?

I suspect the issue might be that you're mounting a single file as a volume, rather than a directory.

# set env variables
ENV FLASK_ENV development
ENV DEBUG true

You also shouldn't need to set these.

Also, PS: using alpine images for Python is generally not recommended: https://pythonspeed.com/articles/alpine-docker-python/

[nleroy917]

Hey @di! Thanks for the detailed example. I swapped out the alpine image for slim and that didn't work, but when I changed my volume mounts to:

        volumes:
          - .:/server

hot reloading started working again. I've used flask inside docker-compose before with alpine images and mounting single files -- hot reloading has never been an issue, so that was odd.

Anyways, thank you for the help!

[di]

Yeah, I think ultimately it's this issue: moby/moby#15793. Glad to help!