Missing secrets file creates a directory?

[aaparmeggiani]

When docker-compose up with the config below, if the file mypass.txt is missing, docker-compose creates an empty directory mypass.txt. Is that expected behaviour?

version: '3.1'

services:
  app:
    image: alpine
    secrets:
      - mypass

secrets:
  mypass:
    file: ./mypass.txt

macOS 10.13.1
Docker version 17.11.0-ce-rc3, build 5b4af4f
docker-compose version 1.17.0, build ac53b73

[shin-]

It's a somewhat unfortunate side-effect of the way we emulate secrets in docker-compose. Incidentally, it will be fixed by #5363, which will error out instead if the specified file is missing.

[RJPercival]

#5363 was never merged, which means this may never have been fixed. Consider re-opening?

[shin-]

It was fixed by #5415

[snpz]

Hi @shin-

I just encountered this issue with docker-compose in WSL.
The secret file does not exist after cloning my repo and compose seems to call mkdir in that moment.
It fails to do so because there is already a file with that id. In my project in the secrets folder also a new directory called like the secret appears.

docker-compose --profile backend up --no-build --detach
WARNING: Service "service-db" uses an undefined secret file "/home/snpz/Portal/secrets/service-db-pass", the following file should be created "/home/snpz/Portal/secrets/service-db-pass"
Creating network "portal_default" with the default driver
Creating service-db ... error

ERROR: for service-db  Cannot create container for service service-db: mkdir /wsl/docker-desktop-bind-mounts/Debian/90cbcba226ca7bbb747654e7273e6f652a56efccc03d744699fc453acdcb3d8b: mkdir /wsl/docker-desktop-bind-mounts/Debian/90cbcba226ca7bbb747654e7273e6f652a56efccc03d744699fc453acdcb3d8b: not a directory

ERROR: for service-db  Cannot create container for service service-db: mkdir /wsl/docker-desktop-bind-mounts/Debian/90cbcba226ca7bbb747654e7273e6f652a56efccc03d744699fc453acdcb3d8b: mkdir /wsl/docker-desktop-bind-mounts/Debian/90cbcba226ca7bbb747654e7273e6f652a56efccc03d744699fc453acdcb3d8b: not a directory
ERROR: Encountered errors while bringing up the project.
make: *** [Makefile:38: backend-up] Error 1

Output of docker-compose version

docker-compose version 1.29.0, build 07737305
docker-py version: 5.0.0
CPython version: 3.7.10
OpenSSL version: OpenSSL 1.1.0l  10 Sep 2019

If you need more input please just let me know.

Maybe this is just how bind mounts work. It took me a while to figure out that I had to delete the created folder in /wsl/docker-desktop-bind-mounts too before I could add my missing secret file to make it work again.

Update:
Possibly it could fail here instead of warning to avoid this?

[philliphoff]

I'm also seeing this behavior (a missing secrets file results in a directory created when the composition is started) with Docker Desktop for Windows (v3.3.1 b63152, with WSL2 engine enabled) but, interestingly, not with Docker Desktop for Mac (v3.3.1 b63152).