[lxc-users] Creating a container as non root

[Serge Hallyn]

Quoting Cal Leeming [Simplicity Media Ltd] (cal.leeming at simplicitymedialtd.co.uk):
> Just wanted to chime in on this, it would seem that creating unprivileged
> containers works fine, at least for download template of Ubuntu.
> 
> However the problem starts when you use "sudo su".
> 
> For example, the following breaks;
> 
> admin$ sudo su deploy
> admin$ lxc-create -t download -n u1 -- -d ubuntu -r trusty -a amd64
> lxc-create: Permission denied - failed to create directory
> '/run/user/999/lock/'

>From this shell, what do 'echo $XDG_RUNTIME_DIR' and 'echo $HOME' say?

> lxc-create: Error opening /tmp/1000/lxc//home/deploy/.local/share/lxc/u1
> 
> But the following works;
> 
> admin$ ssh deploy at 127.0.0.1
> admin$ lxc-create -t download -n u1 -- -d ubuntu -r trusty -a amd64
> Setting up the GPG keyring
> Downloading the image index
> 
> It would seem that lxc-create is picking up a uid 999 (admin) for the lock,
> and uid 1000 (deploy) for the tmp directory.
> 
> I had a quick look at the source but couldn't pin point where/why this was
> happening.
> 
> Although there are other issues with creating unprivileged containers (as
> per your previous discussion), this is probably a bug in its own rights.
> 
> Thoughts?
> 
> Cal
> 
> 
> 
> On Thu, Jan 9, 2014 at 4:11 PM, Serge Hallyn <serge.hallyn at ubuntu.com>
> wrote:
> 
> > Sounds good.  It might be worthwhile having a 'lxc-setup-images' command
> > which requires root and builds the base images.  Then unprileged users
> > could untar/unsquash those images.
> >
> > To be clear, I absolutely *can* create and run ubuntu-cloud images
> > without being root.
> >
> > -serge
> >
> > Quoting Cal Leeming [Simplicity Media Ltd] (
> > cal.leeming at simplicitymedialtd.co.uk):
> > > It's also worth mentioning that fakeroot/fakechroot have some nasty
> > issues
> > > with debootstrap;
> > > https://bugs.launchpad.net/ubuntu/+source/fakechroot/+bug/1265857
> > >
> > > One theory I'm exploring is building "base images" on a machine that does
> > > have root, by running debootstrap on every flavor/arch then using
> > > mksquashfs to compress it down into an image. You could then use
> > unsquashfs
> > > to force whatever uid/gid you wanted, then fakechroot/fakeroot to make
> > > whatever changes you need to the container before launching. The downside
> > > is that there is no public mirror that offers this at the moment (other
> > > than the latest 13.x ubuntu, which contains a filesystem.squashfs you can
> > > extract, but it's 700mb). You could create your own set of base images,
> > > then wrap scripts around them to create the templates, but this is
> > > absolutely not going to work out of the box, there is a lot of tedious
> > work
> > > involved.
> > >
> > > I'm planning on doing a better write up about this (as its something I'm
> > > actively working on), will update this thread at a later date.
> > >
> > > Hope this helps a bit
> > >
> > > Cal
> > >
> > >
> > >
> > >
> > > On Thu, Jan 9, 2014 at 3:39 PM, Michael H. Warfield <mhw at wittsend.com
> > >wrote:
> > >
> > > > On Thu, 2014-01-09 at 08:08 +0200, Kevin Wilson wrote:
> > > > > Hello,
> > > > > I believe that creating a container as non root user should be
> > > > straight-forward.
> > > >
> > > > Sigh...  I'm afraid not...
> > > >
> > > > Funny, Serge and I just had a couple of comments in exchange about this
> > > > very thing with regards to templates.  He's been working on getting
> > > > containers to run under unprivileged users and I know the Fedora and
> > > > CentOS templates will not even run under a non-user (they check).  His
> > > > remark was that most templates will not and can not, including the
> > > > Ubuntu template.  Problem with the Ubuntu template (and, presumably the
> > > > Debian template) is the use of debboot which, in turn, uses mknod to
> > > > create devices for the container - and you're then toast.
> > > >
> > > > The problem there is that there are going to be privileged operations
> > > > (chown, mknod, etc) that are simply going to require privileges in the
> > > > host which are not available to the non-priv user.
> > > >
> > > > I'm not so sure about the busybox template but I wouldn't be
> > optimistic.
> > > > It does look like it checks to see if it's in a user namespace and uses
> > > > mknod if not and does something else if it is.  So, it looks like it
> > > > SHOULD work.  But you have to have user namespaces set up to work.
> > > >
> > > > Once a container is created, it should be possible to run it under a
> > > > non-priv user if you have a recent enough kernel along with the latest
> > > > lxc tools.  But it seems likely we could ever navigate the morass of
> > > > creating a template using lxc-create as a non-priv user.
> > > >
> > > > > I added a user named "test" and I am trying to create a container
> > (see
> > > > > below the sequence). I am running latest lxc git
> > > > > (built from source, as root)  on Fedora 20.
> > > >
> > > > > useradd test
> > > > > su test
> > > > >
> > > > > lxc-create -t busybox -n busyboxTest
> > > > > I get:
> > > > >
> > > > > You lack access to /home/test/.local/share/lxc/
> > > > > I ran;
> > > > > mkdir -p /home/test/.local/share/lxc/
> > > > >
> > > > > Then again:
> > > > > lxc-create -t busybox -n busyboxTest
> > > > > lxc-create: Permission denied - failed to create directory
> > > > '/run/user/0/lock/'
> > > > >
> > > > > failed to create lock
> > > > > System error loading container
> > > > >
> > > > > What should I do ?
> > > > >
> > > > > Regards,
> > > > > Kevin
> > > >
> > > > Regards,
> > > > Mike
> > > > --
> > > > Michael H. Warfield (AI4NB) | (770) 978-7061 |  mhw at WittsEnd.com
> > > >    /\/\|=mhw=|\/\/          | (678) 463-0932 |
> > > > http://www.wittsend.com/mhw/
> > > >    NIC whois: MHW9          | An optimist believes we live in the best
> > of
> > > > all
> > > >  PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of
> > it!
> > > >
> > > >
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