[docker]Full container capabilities (–privileged)

Full container capabilities (–privileged)

$ docker run -t -i --rm ubuntu bashroot@bc338942ef20:/# mount -t tmpfs none /mntmount: permission denied

This will not work, because by default, most potentially dangerous kernel capabilities are dropped; including cap_sys_admin (which is required to mount filesystems). However, the --privileged flag will allow it to run:

$ docker run -t -i --privileged ubuntu bashroot@50e3f57e16e6:/# mount -t tmpfs none /mntroot@50e3f57e16e6:/# df -hFilesystem      Size  Used Avail Use% Mounted onnone            1.9G     0  1.9G   0% /mnt

The --privileged flag gives all capabilities to the container, and it also lifts all the limitations enforced by the device cgroup controller. In other words, the container can then do almost everything that the host can do. This flag exists to allow special use-cases, like running Docker within Docker.

参考:

https://docs.docker.com/engine/reference/commandline/run/#full-container-capabilities---privileged