Personalized Filesystem (was: Hiding nodes with unionmount)

[olafBuddenhagen]

Hi,

On Thu, Jul 30, 2009 at 09:26:11PM +0200, Arne Babenhauserheide wrote:
> Am Donnerstag, 30. Juli 2009 14:37:39 schrieb Sergiu Ivanov:

> $ ln / chroot/real_root
> $ chroot chroot /bin/bash
> $ settrans -a / mine real_root

Much easier to settrans first:

   settrans myroot mine / && chroot myroot

> Is it possible to just unionmount / on another node and then chroot to
> it? 

Yes, that should work:

   settrans myroot unionfs / --mount overlay && chroot myroot

(BTW, this is an obvious use case for union-mounting with something
different than the underlying node -- why didn't I see this before? I'm
glad now that we decided to go with the --mount option to unionfs: it's
so much more powerful than a "pure" unionmount :-) )

> The goal is to have / with some modifications. The "mine" translator
> is a theoretical translator which turns the system into my private
> system - though only for me :) 
> 
> It should be able to modify the system and save all changes I do to
> the system in a personal file - and only there. 
> 
> That would even allow me to do a "rm -rf /" which would naturally make
> the system unusable for me (my / would be empty), but wouldn't affect
> anyone else. My personal environment would then simply contain a
> notice for the filterfs that it should filter out all files :) 

Yes, this is very desirable. I have contemplated it a couple of years
ago; and we actually discussed something like that a while back, in the
discussion about allowing users to locally install packages with dpkg.
This is very relevant, as this thing won't work smoothly without
integration with the package manager -- any upgrade to the global system
could break my local environment otherwise. Don't remember whether we
explicitely talked about this point in the previous discussion.

-antrik-