Puppet users - Jan 2007 - syntax question

I need to know how to do the following in puppet.

Say I have three classes, (c1,c2,c3) that are not related.  These classes could
be considered "attributes" that may or may not apply to an individual
host on my network.  I need to know how to write a manifest, or series of
manifests to allow me trigger a command (call it ''foo'') if all
three classes are defined.  I also need to be able to trigger a different
command (bar) if c1 and c3 are defined, but c2 is not.

How would this look in puppet?

For those of you familiar with cfengine, this would be similar to:

    c1.c2.c3::
        foo

    c1.!c2.c3::
        bar


Thanks.

Nathan T. Dabney
Senior System Administrator, Infrastructure
LAIKA, Inc.

On Jan 7, 2007, at 7:29 PM, Nathan Dabney wrote:
> I need to know how to do the following in puppet.
>
> Say I have three classes, (c1,c2,c3) that are not related.  These  
> classes could be considered "attributes" that may or may not
apply
> to an individual host on my network.  I need to know how to write a  
> manifest, or series of manifests to allow me trigger a command  
> (call it ''foo'') if all three classes are defined.  I also
need to
> be able to trigger a different command (bar) if c1 and c3 are  
> defined, but c2 is not.
>
> How would this look in puppet?
>
> For those of you familiar with cfengine, this would be similar to:
>
>     c1.c2.c3::
>         foo
>
>     c1.!c2.c3::
>         bar
Puppet has some support for thinking of classes as cfengine does, but  
I don''t think many use it so it''s not all that developed.

Basically, classes in cfengine are equivalent to tags in Puppet.  If  
you include a class in Puppet, then the host gets tagged with that  
class:

     class yayness {
         exec { "/bin/echo yayness": }
     }

     include yayness

     if tagged(yayness) {
         exec { "/bin/echo in yayness": }
     }

Produces:

notice: /Exec[/bin/echo in yayness]/returns: executed successfully
notice: /yayness/Exec[/bin/echo yayness]/returns: executed successfully

The only quirk right now is that tagging is (unfortunately) file- 
order dependent.  That is, you can only test for tags after the  
classes have been included.  I hope to find a way to fix this at some  
point, but no one has even asked for it so it''s not been a priority.   
You can be guaranteed that tags are always set as soon as a class is  
entered, though, so you can do those ''tagged'' tests inside the
class
definitions and be sure they behave.

At this point, as I mentioned, people aren''t really using this  
functionality in Puppet, so there isn''t much around it.  Your only  
real option is to use if/else structures to create something like  
this; there''s no boolean type in Puppet like cfengine''s
classes.
I''ve considered creating it, but you''re the first to ask for
it, so I
haven''t bothered.

  --
  Life isn''t fair. It''s just fairer than death,
that''s all.
      -- William Goldman
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  Luke Kanies | http://reductivelabs.com | http://madstop.com