Docker File Location for Asp.Net core

Question

I am running Docker in Windows, using Linux containers.

I have an asp.net core hello-world app that writes a text file:

        var path = Path.Combine(
            Directory.GetCurrentDirectory(), "text.txt");

        System.IO.File.WriteAllText(path, "text");

Directory.GetCurrentDirectory() comes back as "/app"

In my docker-compose I map /app to /usr/xxxxx

volumes:
  - /app:/usr/xxxxx

My question is: Where on my Windows file system is the /usr/xxxxx? I want to back it up so that it stays after containers are removed.

Answer 1

Volumes (actually bind-mounts ) use the format host-path:container-path .

It looks like you put it in the wrong order in the docker-compose file. Also, as there is no folder called /usr/xxx on windows, just use a path that exists instead.

For example, you can create a directory called "backup" inside the directory with the docker-compose file, and then modify the docker-compose file like so

volumes:
  -  "./backup:/app"

In the standard Dockerfile that Visual Studio generates, your application dll's are copied into /app . Therefore, it might be a bad choice to use /app . I'm actually not sure what happens if the bind-mount directory already exists with different data inside the container. But you could just write the file to another directory and use that instead.