[lxc-users] lxc 2.0 => 3.0 and ubuntu.common.conf (and lxc-templates dpkg)

Fri Jul 20 12:57:09 UTC 2018

On Fri, Jul 20, 2018 at 11:09:11AM +0200, Christian Brauner wrote:
> On Tue, Jul 17, 2018 at 04:11:43PM -0400, Adrian Pepper wrote:
> > > From arpepper at uwaterloo.ca Mon Jul 16 15:40:10 2018
> > > From: AR Pepper <arpepper at uwaterloo.ca>
> > > To: "lxc-users at lists.linuxcontainers.org"
> > > 	<lxc-users at lists.linuxcontainers.org>
> > > CC: AR Pepper <arpepper at uwaterloo.ca>
> > > 
> > > This message devolved from a different query which is implied here together
> > > with its answer.  Perhaps this result will save some other people some time.
> > > 
> > > 
> > > I just discovered a stupid user (lxc administrator) trick.
> > > 
> > > Suppose you have an lxc setup you are migrating from Ubuntu 16.04 to 18.04.
> > > (Going from lxc 2.0(2.0.8) to 3.0(3.0.1)).
> > > (Doing a fresh install of Ubuntu 18.04 and modifying to match).
> > > 
> > > If under Ubuntu 18.04 you install the "lxc" package, but not the
> > > "lxc-templates" package, then, even after "lxc-update-config",
> > > some of your lxc config files will fail because of...
> > > (for example)
> > > 
> > > lxc.include = /usr/share/lxc/config/ubuntu.common.conf
> > > 
> > > 
> > > As an even stupider user trick, things seem to superficially work properly
> > > if you simply remove the "ubuntu." from the config file, leaving
> > > 
> > > lxc.include = /usr/share/lxc/config/common.conf
> > > 
> > > It turns out /usr/share/lxc/config/ubuntu.common.conf (and many others)
> > > are provided under Ubuntu by the "lxc-templates" package.
> > > 
> > > Hmm.  Could lxc-update-config (be changed to) remark upon the need for
> > > the lxc-templates package?  Or maybe just make a general observation
> > > that the include file does not exist?  ("Something is wrong")
> > 
> > While waiting for the above message to actually appear, I thought of a
> > perhaps better set of comments on the same thing.  As a follow-up to
> > Christian Brauner's packaging change announcement.
> > 
> > I eventually wonder (below) if "lxc" could once again have "lxc-templates"
> > as a dependency, even though "lxc-utils" does[should] not.  Since "lxc"
> > is now branded as a transitional package => lxc-utils.
> 
> That's a packaging call that Stéphane needs to make.

No it won't as that'd require Canonical to provide LTS (5 years) support
on lxc-templates which we very much don't want to do.

> 
> > 
> > 
> > Adrian Pepper
> > arpepper at uwaterloo.ca
> > 
> > > From lxc-users-bounces at lists.linuxcontainers.org Sat Apr  7 12:04:56 2018
> > > From: Christian Brauner <christian.brauner at canonical.com>
> > > Subject: [lxc-users] LXC 3.0.0: Packaging Changes To Be Aware Of
> > > 
> > > 
> > > Hey everyone,
> > > 
> > > LX{C,FS,D} upstream here. :)
> > > 
> > [...]
> > > 
> > > Here is a list of what we consider will most likely affect you as packagers:
> > > 
> > > 1. **Important** the lxc-templates have been moved out of the main LXC tree
> > >    into a separate repository
> > >    https://github.com/lxc/lxc-templates
> > > 
> > >    This means that without this separate package LXC will now only come with
> > >    the following templates:
> > > 
> > >    lxc-busybox
> > >    lxc-download
> > >    lxc-local
> > >    lxc-oci
> > > 
> > 
> > The templates had been in a separate "lxc-templates" package also in
> > Ubuntu 16.04.
> > But "lxc-templates" had been a dependency of the "lxc" package and
> > was therefore dragged in automatically.
> > 
> > But with the change indicated in the quoted announcement, it no longer
> > gets so dragged in.
> > 
> > But an unmentioned associated effect of not dragging in lxc-templates
> > is that most of the files
> > /usr/share/lxc/config/*.conf
> > are no longer put in place.
> > 
> > So "lxc-templates" must be installed not only to use the templates
> > to generate new containers.  It must be installed if you are going
> > bring forward containers from Ubuntu 16.04 (lxc 2.0), which had been
> > generated using templates.
> > 
> > "lxc-update-config" works without complaint on containers whose config
> > includes, for example
> > 
> >    lxc.include = /usr/share/lxc/config/ubuntu.common.conf
> > 
> > But the containers still fail afterwards because the include is not
> > satisfied.  (They fail, that is, until "lxc-templates" is installed).
> > 
> > (Assume here that a common way of producing an upgraded host system,
> > e.g. Ubuntu 18.04 versus 16.04, is to produce a new minimal 18.04
> > system and then apply all recorded "apt install" commands corresponding
> > to actual desired packages (yes, modifications are sometimes needed,
> > but...).  The old 16.04 system need not have explicitly done "apt
> > install lxc-templates" and so that could be overlooked in 18.04).
> > 
> > Since "lxc" is now branded as a transitional package => lxc-utils,
> > could "lxc" have lxc-templates as a dependency, even though lxc-utils
> > will not?
> > 
> > 
> > Adrian Pepper
> > arpepper at uwaterloo.ca
> > 
> > _______________________________________________
> > lxc-users mailing list
> > lxc-users at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-users

-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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