How-To fix access issues with docker bind mounts

Owned by Simone Conrad
Sept 20, 2024
1 min read

About

If bind mount is used with docker within a docker container, this bind mount obtains a uid and guid from the host machine. It is recommended to run container images as a user. In this case, the docker container does not have full access (777 or 666).

Content

Instruction

  • Create a folder /kgs on your host machine

  • The created folder is granted full access chmod -R 777

  • Start the Docker image with a shell

    • docker run -it --rm -v /kgs:/kgs myImage:MyVersion /bin/sh

  • The shell is started in the docker container

    • enter /kgs

    • touch abc

    • exit container

  • Check the UID and GUID of the created file in the created /kgs folder

  • Restricted rights are assigned to the /kgs folder again chmod -R 660

    • Only the owner and the group may access

  • On the host machine, check in /etc/passwd whether there is a group with the GUID. If not, create with

    • groupadd -g >GUID> MYGROUPNAME

  • Assign the previously created group to the /kgs folder

    • chgrp -R MYGROUPNAME /kgs

  • Restart the docker container

    • docker run -it --rm -v /kgs:/kgs myImage:MyVersion /bin/sh

  • It should now be possible to write to the folder despite restricted rights

  • The docker container can be started normally and the service has access