MacOS: How to mount volumes using docker-compose.yml and Dockerfile?

Question

My project's folder structure looks like:

+ cython_test/
    + ny/
        + nyc/
            + docker-compose.yml
            + Dockerfile
            + pigeon.py
            + data/
                + temps.txt

The docker-compose.yml :

version: '2.1'
services:
  worker:
    build: .  
    volumes: 
      - ./:/opt

The Dockerfile :

FROM python:3.6-alpine3.10

RUN sleep 5000

To get the container started, I do:

docker-compose -f "ny/nyc/docker-compose.yml" up -d --build

And I get the output:

Alexs-MacBook-Pro:cython_test alexvissup$ cd "/Users/alexvissup/Codes/cython_test"
Alexs-MacBook-Pro:cython_test alexvissup$ docker-compose -f "ny/nyc/docker-compose.yml" up -d --build
Creating network "nyc_default" with the default driver
Building worker
Step 1/2 : FROM python:3.6-alpine3.10
 ---> 92a867c54c0f
Step 2/2 : RUN sleep 5000
 ---> Running in fdeb933e6cfc

When I exec into the container I expect to go into /opt and see everything inside my local nyc folder, but it's empty.

I'm required to specify the volumes in the docker-compose.yml . Is this possible? What am I doing wrong?

Answer 1

Docker volume will be created when the containers are created and not during the build time. Your docker file is execting a sleep command for a long time, therefore the docker-compose does not create the container until the sleep functions completely finish. (I don't see why you need the sleep at all, it is not a common thing in Docker world)

The second issue that you have here is that you do not define the container command nether in the docker-compose nor in the Dockerfile. You must define one in order to keep the container running after building the docker image.

You can try to use the below command to fix the issue (You may need to install python dependencies also )

FROM python:3.6-alpine3.10
# RUN pip install flask -- if you need to have some dependencies
WORKDIR /opt
ENTRYPOINT ["python", "pigeon.py"]