Problem statement:

When you run docker container, lots of enterprise organization do not allow you to run container as root or as sudo because it compromises the container file system access and for some other various reason.

I run into same situation while that I wanted to run the process as a user but my virtual machine instance username doesn’t match with container’s username’s UID.

e.g.

$ id
uid=1000(circleci) gid=1000(circleci) groups=1000(circleci),4(adm),20(dialout),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),117(netdev),118(lxd),997(docker)

$ docker run -it --rm cimg/node:$CIRCLECI_NODE_TAG id
uid=3031(circleci) gid=3031(circleci) groups=3031(circleci),4(adm),20(dialout),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),117(netdev),118(lxd),997(docker)

so when you mount the file and run as circleci user it would fail.

Resolution:

If you want to run this as same uid as what it has on VM