I'm trying to mount a directory containing a file some credentials onto a container with the -v flag, but instead of mounting that file as a file, it mounts it as a directory:
Run script:
$ mkdir creds/
$ cp key.json creds/key.json
$ ls -l creds/
total 4
-rw-r--r-- 1 root root 2340 Oct 12 22:59 key.json
$ docker run -v /*pathToWorkingDirectory*/creds:/creds *myContainer* *myScript*
When I look at the debug spew of the docker run command, I see that it creates the /creds/ directory, but for some reason creates key.json as a subdirectory under that, rather than copying the file.
I've seen some other posts saying that if you tell docker run to mount a file it can't find, it will create a directory on the container with the filename, but since I didn't specify the filename and it knew to name the new directory 'key.json' it seems like it was able to find the file, but created it as a directory anyway? Has anyone run into this before?
In case it's relevant, the script is being run in Docker-in-Docker in another container as part of GitLab's CI process.
You are running Docker-in-Docker, this means when you specify a -v volume, Docker will look for this directory on the host since the shared sock enabling Docker-in-Docker actualy means your run command starts a container alongside the runner container.
I explain this in more detail in this SO answer:
https://stackoverflow.com/a/46441426/2078207
Also notice the comment below this answer to get a direction for a solution.