How to make a mount shared in Docker?

Question

I'm trying to start a project in Docker (directly from the Debian distro) in Windows 10 and getting this error:

$ docker compose up -d
[+] Running 0/0
 ⠋ Container core_php74_1  Creating                                                                                                                            0.0s
Error response from daemon: path /home/me/path/to/project is mounted on / but it is not a shared mount.

How to make the mounted path /home/me/path/to/project a shared mount?

Juneberry

Answer 1

I got the same error after updating docker for desktop to 3.5.2 (66501). I have created volumes with trailing slashes in my docker-compose.yml. I removed them to fix the problem.

Change

volumes:
  - ./:/app/
  - ./another/folder:/folder/

To

volumes:
  - ./:/app
  - ./another/folder:/folder

Cranford

Thanks a million Colin for your useful fix. I fixed the issue just like what you said. Don't know why it only affects Windows 10 with docker desktop 4.0.0 (67817) but it works on my Mac. – Muskogean

I just wanted to chime in that I was having this issue and it had to do with trying to seed my MySQL database with /docker-entrypoint-initdb.d/:ro, which wasn't working anyways to automatically run my database seeds. Removing the /:ro resolved the issue for me. – Cheater

@KyleCrossman You could've remove only the trailing / so your configuration would've be /docker-entrypoint-initdb.d:ro. :ro is for read-only – Cranford

just want to report this happening on win10 docker desktop 4.2.0 (70708) – Ligon

Answer 2

You can NOT mount into docker to "/" In your docker-compose.yml must be this lines or similar for windows :

volumes:
  - /home/me/path/to/project:/path/in/image

Doing

Thank you for your answer. But this configuration is working on Linux hosts. So the mounting itself will be correct. Otherwise, it would not be possible to start the container(-s) anywhere. – Juneberry