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Re: packages "bug"


From: Brendan Strejcek
Subject: Re: packages "bug"
Date: Sat, 12 Nov 2005 19:02:53 -0600
User-agent: Mutt/1.5.6+20040818i

Mark Burgess wrote:

> Your example doesn't make sense to me, because you are asking to the
> same package twice - so it seems reasonable to me that cfengine would
> think it was unnecessary to do the same thing again. The two checks
> are identical?

The checks are not identical because they define different classes. Two
separate tasks could do very different things based on that information.

Best,
Brendan

--
Senior System Administrator
The University of Chicago
Department of Computer Science

http://www.cs.uchicago.edu/people/brendan

http://people.cs.uchicago.edu/~brendan


> On Fri, 2005-11-11 at 16:40 -0600, Brendan Strejcek wrote:
> > cfengine locking can get in the way of package definitions. For example,
> > consider the following:
> > 
> > ########################################################################
> > 
> > ==> main.cf <==
> > 
> >     #!/usr/sbin/cfagent -qvf
> >     
> >     control:
> >         actionsequence = ( packages )
> >     
> >     import:
> >         /tmp/one.cf
> >         /tmp/two.cf
> > 
> > ==> /tmp/one.cf <==
> > 
> >     packages:
> >         bash
> >             pkgmgr=rpm
> >             define=bash_pkg_installed
> >     
> >     alerts:
> >         bash_pkg_installed::
> >             "one.cf: bash_pkg_installed class defined"
> > 
> > ==> /tmp/two.cf <==
> > 
> >     packages:
> >         bash
> >             pkgmgr=rpm
> >             define=bash_package_installed
> >     
> >     alerts:
> >         bash_package_installed::
> >             "two.cf: bash_package_installed class defined"
> > 
> > ########################################################################
> > 
> > When I run that, this is what happens:
> > 
> >     Installable classes = ( bash_pkg_installed bash_package_installed )
> >     ...
> >     RPMCheckPackage(): Requested bash eq ANY
> >     cfengine:: Nothing scheduled for packages.packages (0/1 minutes elapsed)
> >     ...
> >     ---------------------------------------------------------------------
> >     Alerts
> >     ---------------------------------------------------------------------
> >     cfengine:: one.cf: bash_pkg_installed class defined
> > 
> > We can see that the second class is not getting defined due to a lock.
> > Why is this bad? It means that any admin that defines a class like
> > this needs to understand the entire site config, or actions predicated
> > on their class may never occur. I suspect other sections may exhibit
> > similar behavior, but I have not tested it yet.
> > 
> > Fundamentally, I think this is a problem of scope and namespaces. I
> > think that is one of the weakest elements of cfengine, so I hope it
> > is addressed in version 3. Namespaces are intimately connected with
> > reusability.
> > 
> > Best,
> > Brendan
> > 
> > --
> > Senior System Administrator
> > The University of Chicago
> > Department of Computer Science
> > 
> > http://www.cs.uchicago.edu/people/brendan
> > 
> > http://people.cs.uchicago.edu/~brendan
> > 
> > 
> > _______________________________________________
> > Help-cfengine mailing list
> > address@hidden
> > http://lists.gnu.org/mailman/listinfo/help-cfengine
> 
> 




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