[Lxc-users] Using common rootfs for multiple containers

[Walter]

Yes, this is possible.

There are multiple approaches, for example:
 1. Creating a snapshot (or outright copy) of a filesystem, then
disposing of it when done.
  (1a) Manually creating a full copy
  (1b) Using a blockstore-provided snapshot facility such as LVM2
 2. Using a snapshot-capable filesystem, and using a snapshot provided
by the filesystem itself (ZFS, BTRFS, etc.)
 3. Mounting read-only, with either of two solutions for writable
portions of the filesystem. This class of solution is very similar to
NFS based root situations (ie. modern PXE-driven diskless network
boot).
  (3a) 'tmpfs' or some other in-memory based write solution where required.
  (3b) Union-mounts.

My advice would be as follows.
 == simplest ==
 (1a) and (1b) are easiest *and* allow the use of arbitrary filesystems.
 == medium hassle==
 (2) is become somewhat common but is more difficult.
 (3b) are more difficult
 == more hassle ==
 (3a) is more hassle up front but is perhaps the neatest solution overall.
 (3b) i have never got working, but should be neat.. it's just not
going to be as widely supported by various kernels out there as (3a)
or (1b).

Personally I use (3a) and (1b).

- Walter