How to access data from a file in a docker volume

Question

I am relatively new to Docker. I am struggling to fetch sensitive data on file which is set a docker volume.

This is how i have setup directory structure in Dockerfile

RUN mkdir /env
RUN touch /env/config.json

This my volume setup in docker-compose.yml

volumes:
      - ./main_app:/main_app
      - ./env/config.json:/env/config.json

I am trying to access data in config.json in Django settings file as shown

with open('/env/config.json') as config_file:
    config = json.load(config_file)

Now when i try to run docker-compose run i get the following error

unknown: Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type

What could be the issue with my setup?

Does the configuration file exist on the host, in that exact path? (If it didn't, Docker would have created a directory, and then you'd get that error.) — David Maze, Apr 04 '21 at 13:38
I am adding the file with this command ```RUN touch /env/config.json``` — Muteshi, Apr 04 '21 at 13:46
So the image should contain an empty file; and when you start the container, you are trying to mount something on the host over that file. Does the file `./env/config.json` exist on the host? — David Maze, Apr 04 '21 at 14:31

score 0 · Answer 1 · answered Apr 04 '21 at 13:36

0

You are tyring to mount a file as a volume and need to change

 - ./env/config.json:/env/config.json

to

 - ./env:/env

answered Apr 04 '21 at 13:36

Kaj Hejer

I modified as shown but then Django is throwing the following error ```FileNotFoundError: [Errno 2] No such file or directory: '/env/config.json'``` – Muteshi Apr 04 '21 at 13:45
Sorry about that! Please try to run your image interactively to see if the files are where you expect them to be by running the image with ```docker run -it ...```. Please see https://docs.docker.com/engine/reference/commandline/run/ for more details about running images interactively. – Kaj Hejer Apr 04 '21 at 13:49
When i run ```ls``` i get ```ls: cannot access '/env': No such file or directory``` – Muteshi Apr 04 '21 at 14:09
Strange... should work. See f.x. https://stackoverflow.com/a/46910980/924036. Sorry, dont have any other ideas at the moment. – Kaj Hejer Apr 04 '21 at 16:46

1 Answers1