[systemd-devel] [PATCH 3/3] nspawn: allow to bind mount journal on top of a non empty container journal dentry

[Lennart Poettering]

On Tue, 29.04.14 00:15, Djalal Harouni (tixxdz at opendz.org) wrote:

> 
> On Fri, Apr 25, 2014 at 08:30:36PM +0200, Tom Gundersen wrote:
> > On Fri, Apr 11, 2014 at 2:45 AM, Djalal Harouni <tixxdz at opendz.org> wrote:
> > > Currently if nspawn was called with --link-journal=host or
> > > --link-journal=auto and the right /var/log/journal/machine-id/ exists
> > > then the bind mount the subdirectory into the container might fail due
> > > to the ~/mycontainer/var/log/journal/machine-id/ of the container not
> > > being empty.
> > >
> > > There is no reason to check if the container journal subdir is empty
> > > since there will be a bind mount on top of it. The user asked for a bind
> > > mount so give it.
> > >
> > > Note: a next call with --link-journal=guest may fail due to the
> > > /var/log/journal/machine-id/ on the host not being empty.
> > >
> > > https://bugs.freedesktop.org/show_bug.cgi?id=76193
> > 
> > Hm, so this will allow some journal entries to be saved on the host
> > and some on the guest, but only one of them
> > will be shown by "journalctl --merge" at any given time... Won't this
> > be confusing? Either way I guess this case
> > should be documented in the manpage (either that it is not allowed, or
> > that it may be confusing)...
> Yes, to be honest, I'm also not sure! but I guess if the user wants to
> move to the host, perhaps give him a chance, or at least document as you
> have suggested, and warn during systemd-nspawn (will verify it later). 
> 
> So I'll wait to see what others think, or perhaps extend journalctl to
> make this part of --merge ... ?

Thinking about this and after having merged your patch earlier, I have
now changed this slightly again, and readded the error message, but
downgraded it to a warning. THis means you get what you ask for by
passing --link-journal= but at least you are informed that somethoing is
weird.

I hope this makes sense,

Lennart

-- 
Lennart Poettering, Red Hat