Puppet users - Feb 2007 - Question on case statements...

Just poking around on the Docs site and went to the facter recipe for VMware.
(http://reductivelabs.com/trac/puppet/wiki/IsVmwareGuestRecipe)

If you look at the bottom, the author states that they were unable to get case
statements to match as a regex.

   case $macaddress {
      "00:0C:29:*":{
         file{ "/etc/running_inside_vmware": ensure => present }
      }
   }

Is there a way to do regex matching in a case statement or is this solely the
realm of facter?

Thanks,
  --Robert

On Feb 6, 2007, at 12:06 PM, Robert Nickel wrote:
> Just poking around on the Docs site and went to the facter recipe  
> for VMware.
> (http://reductivelabs.com/trac/puppet/wiki/IsVmwareGuestRecipe)
>
> If you look at the bottom, the author states that they were unable  
> to get case
> statements to match as a regex.
>
>    case $macaddress {
>       "00:0C:29:*":{
>          file{ "/etc/running_inside_vmware": ensure => present
}
>       }
>    }
>
> Is there a way to do regex matching in a case statement or is this  
> solely the
> realm of facter?
Puppet currently has no support for regexes, so you''re restricted to  
doing this within Facter at this point.

At some point something like this will need to happen, but I''m going  
to avoid it for as long as possible.  It might make more sense to  
have an external server-side module that can do this rather than  
extend the language, because Puppet''s language is really about  
specification not about computation.

  --
  Hoare''s Law of Large Problems:
     Inside every large problem is a small problem struggling to get  
out.
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com

> >    case $macaddress {
> >       "00:0C:29:*":{
> >          file{ "/etc/running_inside_vmware": ensure =>
present }
> >       }
> >    }
> 
> Puppet currently has no support for regexes, so you''re restricted
to
> doing this within Facter at this point.
> 
> At some point something like this will need to happen, but I''m
going
> to avoid it for as long as possible.  It might make more sense to  
> have an external server-side module that can do this rather than  
> extend the language, because Puppet''s language is really about  
> specification not about computation.
Would it make sense to make this external server-side module an 
extension of facter?  I''m thinking of the case where there''s a
"more"(all?) knowing server capable of giving remote facts to
facter.  Right now, this could be done with some RPC calls, but
are there plans to standardize that?

--mac

On Feb 6, 2007, at 4:31 PM, Chris McEniry wrote:
>
> Would it make sense to make this external server-side module an
> extension of facter?  I''m thinking of the case where
there''s a
> "more"(all?) knowing server capable of giving remote facts to
> facter.  Right now, this could be done with some RPC calls, but
> are there plans to standardize that?
Frankly, I haven''t thought about it all that much; it just seems like  
a natural way to push complexity out of the language.

The more I wrestle with the different kinds of problems we need to  
express in our configurations, the more it seems to make sense to  
build stacks of small tools with limited semantic domains.  Facter is  
clearly one such tool, and I''ve been thinking of creating another  
tool that just handles node/class mapping (i.e., a tool that accepts  
a list of facts for a host and produces the class memberships for  
that host).

This idea of a server-side facter is a pretty good idea, and would  
probably just be added to the stack.  This is literally the first  
time I''ve thought about it, but it shouldn''t be too hard to
reuse the
Facter code to build such a tool; then it would just be a question of  
how to insert this tool between the client and the compilation phase.

If we can keep Puppet''s language focused on specifying the details of  
resources, and not force it to also handle class membership  
determination, I think we''ll be a lot happier.  At least, I will be.

This is definitely something to think about.  Anyone else feel any  
particular way about this?

  --
  The one thing more difficult than following a regimen is not  
imposing it
  on others.           -- Marcel Proust
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com