[SSSD] Design discussion: autofs integration

Ian Kent ikent at redhat.com
Sat Dec 10 00:30:00 UTC 2011


On Fri, 2011-12-09 at 09:48 +0100, Jakub Hrozek wrote:
> On Fri, Dec 09, 2011 at 08:01:44AM +0800, Ian Kent wrote:
> > On Thu, 2011-12-08 at 17:52 +0100, Jakub Hrozek wrote:
> > > Hi,
> > > 
> > > I have created a wiki page summarizing my design proposal on integrating
> > > SSSD with automounter:
> > > https://fedorahosted.org/sssd/wiki/DesignDocs/AutofsIntegration
> > > 
> > > Feedback is much appreciated - a reply to this email would probably work
> > > best. The target of this work is 1.8
> > 
> > Thanks for writing this summary, it's excellent.
> > There's not much I have to say about it because it is already quite
> > thorough.
> > 
> > One thing I dislike about the discussion, and while I let it pass in
> > bugs and mailing list discussions, I think it is wrong to put it in
> > public design documents. The statement "autofs abuses the nsswitch.conf
> > configuration file" I find a little offensive. autofs uses that
> > configuration file and parses only the "automount" entry using the same
> > semantic behavior as nss, so the word "abuse" is wrong and a little rude
> > IMHO.
> 
> I'm sorry -- I didn't mean to offend you and perhaps abuse was a strong
> word. I've changed the design docs.

None taken, the word is simply to strong for the message that is being
conveyed.

> 
> That said, I'm still not convinced that it is a good idea to use another
> application's config file.
> 
> My main concern is that users often mistakenly think that there is a
> standard glibc interface defined. Also, when the shared config file
> changes (not that it's likely that nsswitch would change drastically),
> you're in trouble -- for instance, sudo suffered recently when Fedora
> changed from using ldap.conf to nslcd.conf

It's hard to argue this point since that is my own opinion as well. But,
in this case, it was so much more sensible to take the risk (the
longevity of this configuration file counted in the decision) and use
this particular configuration.

During the initial autofs version 5 development I spent a sufficient
amount of time (quite a bit actually) trying to use the glibc nss
interface for the autofs ldap lookup module (including writing the glibc
backend since there were no nss "automount" modules at all) to work out
that using it was going to be very painful for me, not to mention that I
would have had to write "all" needed source modules myself, including
their backend component and hope they would be accepted into glibc
within a time frame that met my tight schedule.

So, the decision was made to break my own rule and re-use large portions
of existing autofs code, and yes, I would have rather used a published
interface, but for better or for worse, that is the way it was done
which happens some times, unfortunately.

Ian





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