Using Docker Engine on Windows Server to Bind One File?

Docker Hub
1

I’m experiencing an issue using Docker Engine on Windows Server 2019 with Linux Kit which does not exist on either Docker for Linux or Docker Desktop for Windows 10.

The scenario is the following – I have an image MyLinuxImage whose execution depends on a root level file /file.txt. Now on both Docker Desktop and Docker Linux, this is an easy thing to configure – simply bind a file onto that file using the argument -v C:\path\myfile.txt:/file.txt . However, on Docker Engine on Windows server, this mount fails with the message:

docker: Error response from daemon: invalid volume specification: 
C:\path\myfile.txt:file.txt:/file.txt': invalid mount config for type "bind": source path must be a directory.

I’ve additionally tried several configurations using the --mount flag, and bind mounts using single file fail using this syntax as well. I’ve experienced this issue on both Docker engine 18 (18.06) and 19 (19.03.5).

Additionally, trying to mount a directory at the root level fails because the root level cannot have a directory mounted to it.

Unfortunately, this image in question is not a home baked one for which I can just move the file location.

So I’m wondering the following

  • Are there any options I may be missing to resolve this issue?
  • Is there a tracking bug for this issue already that anyone is aware of?

Update: Answer found

Okay, I found a solution. While bind mounting does not work for single files using docker engine on windows, it can be worked around by first creating the container, then copying the file into the container, then starting that container.

docker container create myimage
docker container cp myfile.txt <id>:/file.txt
docker start <id>
2

If you would use docker swarm, you could use config or secret to mount a single file into a path inside the container.

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Thanks! Sounds like it could work, though in my situation orchestration is handled by the application and so swarm would be a heavy investment. Fortunately there is an easy solution which I missed at first, which I added to the question – just precreate the container and copy the file into it.