How to create a container with the same root fs as the host?

Hello,

I'm trying to create a container that runs in its own namespaces (mount, net, uts, etc.). But the special thing I want to achieve is that it has the same view on the filesystem as the root, unless it tries to modify its own VFS.

For that I try to specify path to rootfs as "/", but the creation of the container does not work this way and fails with "invalid argument":

sudo ./test-runc hostname
2018/10/13 10:34:34 exec: "hostname": executable file not found in $PATH
2018/10/13 12:34:34 Failed to launch the container: container_linux.go:336: starting container process caused "exec: "hostname": executable file not found in $PATH"

Here is the full example I tried to run: test-runc

I still want to run the container in a separate mount namespace. For example, to be able to remount /proc, but I still want the rest of the host VFS be visible from the inside of the container.

Start by reading the linked test-runc example and the runc behavior around a rootfs path of "/", then run the shown hostname command to reproduce the failure. Done would mean a container can use separate namespaces while retaining the host filesystem view and still support remounting /proc, as described.