Puppet users - Sep 2007 - "Have I included class X" function?

Anyone know if it would be straightforward to extract this information
from Puppet, probably in a custom function:

The classes included as a result of the client''s parsed configuration
- or -
Am I in class X as a result of my parsed configuration?

I''m thinking it would result in a more elegant manifest if classes X
and
Y behaved differently if they were both included compared to if just
class X or class Y was.  Rather than some ugly Z class.

Cheers,
Derek
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On Sep 25, 2007, at 10:42 AM, <Derek.Whayman@barclayscapital.com> wrote:
> Anyone know if it would be straightforward to extract this information
> from Puppet, probably in a custom function:
>
> The classes included as a result of the client''s parsed
configuration
> - or -
> Am I in class X as a result of my parsed configuration?
>
> I''m thinking it would result in a more elegant manifest if classes
> X and
> Y behaved differently if they were both included compared to if just
> class X or class Y was.  Rather than some ugly Z class.
It should be pretty darn straightforward.

You should be able to just do something like this:

   if class_scope("class_name")
     return true
   else
     return false
   end

Note that class_scope expects a fully-qualified class.  If you need  
to look up a class name, then you can do this:

   if class_scope(findclass("unqualified-class"))
     ...
   end


  --
  Susskind''s Rule of Thumb:
      Don''t ask what they think. Ask what they do.
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com

Works perfectly, much obliged.

In addition to the justification below, this means the only real
downside of the dynamic variable scoping model - where an "assignment"
to a variable in one class is not visible in a sister class - is no
longer an issue in most cases.  The manifest can be refactored to use
this code instead.

For example, if I have a templated file that has inputs from two classes
(that are not hierarchical) it''s now easy to organise this.

I know that said file should be managed by a custom type with resources
in both classes, but hey sometimes I just don''t have the time to go
that
far ;-)

Many thanks,
Derek


-----Original Message-----
From: puppet-users-bounces@madstop.com
[mailto:puppet-users-bounces@madstop.com] On Behalf Of Luke Kanies
Sent: 25 September 2007 17:41
To: Puppet User Discussion
Subject: Re: [Puppet-users] "Have I included class X" function?

On Sep 25, 2007, at 10:42 AM, <Derek.Whayman@barclayscapital.com> wrote:
> Anyone know if it would be straightforward to extract this information
> from Puppet, probably in a custom function:
>
> The classes included as a result of the client''s parsed
configuration
> - or -
> Am I in class X as a result of my parsed configuration?
>
> I''m thinking it would result in a more elegant manifest if classes
X
> and Y behaved differently if they were both included compared to if 
> just class X or class Y was.  Rather than some ugly Z class.
It should be pretty darn straightforward.

You should be able to just do something like this:

   if class_scope("class_name")
     return true
   else
     return false
   end

Note that class_scope expects a fully-qualified class.  If you need to
look up a class name, then you can do this:

   if class_scope(findclass("unqualified-class"))
     ...
   end


  --
  Susskind''s Rule of Thumb:
      Don''t ask what they think. Ask what they do.
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com


_______________________________________________
Puppet-users mailing list
Puppet-users@madstop.com
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------------------------------------------------------------------------
For important statutory and regulatory disclosures and more information about
Barclays Capital, please visit our web site at http://www.barcap.com.

Internet communications are not secure and therefore the Barclays Group does not
accept legal responsibility for the contents of this message.  Although the
Barclays Group operates anti-virus programmes, it does not accept responsibility
for any damage whatsoever that is caused by viruses being passed.  Any views or
opinions presented are solely those of the author and do not necessarily
represent those of the Barclays Group.  Replies to this email may be monitored
by the Barclays Group for operational or business reasons.

Barclays Capital is the investment banking division of Barclays Bank PLC, a
company registered in England (number 1026167) with its registered office at 1
Churchill Place, London, E14 5HP. This email may relate to or be sent from other
members of the Barclays Group.
------------------------------------------------------------------------

Ah, there''s only one point to note about this.  It was in the back of
my
mind when I posed the question, I think I was blinded by the
possibilities.

E.g.
node myhost {
  include dummycat
  include base
}

If I call class_scope("dummycat") within a class included from base it
works fine.  However:

node myhost {
  include base
  include dummycat
}

If I now call class_scope("dummycat") within a class included from
base
it is always false.

This is presumably because the included classes are built during the
parsing - and the call to class_scope is during the parsing - and at
what point depends on the ordering in the manifest.

Making the manifests order-sensitive is clearly not the Puppet Way.
It''s slightly uglier than before, but it still works for what
I''m trying
to do provided I don''t stray beyond these boundaries.

Maybe I should move back towards external node classification ;-)

Regards,
Derek


-----Original Message-----
From: puppet-users-bounces@madstop.com
[mailto:puppet-users-bounces@madstop.com] On Behalf Of Whayman, Derek:
IT (LDN)
Sent: 26 September 2007 13:10
To: puppet-users@madstop.com
Subject: Re: [Puppet-users] "Have I included class X" function?

Works perfectly, much obliged.

In addition to the justification below, this means the only real
downside of the dynamic variable scoping model - where an "assignment"
to a variable in one class is not visible in a sister class - is no
longer an issue in most cases.  The manifest can be refactored to use
this code instead.

For example, if I have a templated file that has inputs from two classes
(that are not hierarchical) it''s now easy to organise this.

I know that said file should be managed by a custom type with resources
in both classes, but hey sometimes I just don''t have the time to go
that
far ;-)

Many thanks,
Derek


-----Original Message-----
From: puppet-users-bounces@madstop.com
[mailto:puppet-users-bounces@madstop.com] On Behalf Of Luke Kanies
Sent: 25 September 2007 17:41
To: Puppet User Discussion
Subject: Re: [Puppet-users] "Have I included class X" function?

On Sep 25, 2007, at 10:42 AM, <Derek.Whayman@barclayscapital.com> wrote:
> Anyone know if it would be straightforward to extract this information
> from Puppet, probably in a custom function:
>
> The classes included as a result of the client''s parsed
configuration
> - or -
> Am I in class X as a result of my parsed configuration?
>
> I''m thinking it would result in a more elegant manifest if classes
X
> and Y behaved differently if they were both included compared to if 
> just class X or class Y was.  Rather than some ugly Z class.
It should be pretty darn straightforward.

You should be able to just do something like this:

   if class_scope("class_name")
     return true
   else
     return false
   end

Note that class_scope expects a fully-qualified class.  If you need to
look up a class name, then you can do this:

   if class_scope(findclass("unqualified-class"))
     ...
   end


  --
  Susskind''s Rule of Thumb:
      Don''t ask what they think. Ask what they do.
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com


_______________________________________________
Puppet-users mailing list
Puppet-users@madstop.com
https://mail.madstop.com/mailman/listinfo/puppet-users
------------------------------------------------------------------------
For important statutory and regulatory disclosures and more information
about Barclays Capital, please visit our web site at
http://www.barcap.com.

Internet communications are not secure and therefore the Barclays Group
does not accept legal responsibility for the contents of this message.
Although the Barclays Group operates anti-virus programmes, it does not
accept responsibility for any damage whatsoever that is caused by
viruses being passed.  Any views or opinions presented are solely those
of the author and do not necessarily represent those of the Barclays
Group.  Replies to this email may be monitored by the Barclays Group for
operational or business reasons.

Barclays Capital is the investment banking division of Barclays Bank
PLC, a company registered in England (number 1026167) with its
registered office at 1 Churchill Place, London, E14 5HP. This email may
relate to or be sent from other members of the Barclays Group.
------------------------------------------------------------------------
_______________________________________________
Puppet-users mailing list
Puppet-users@madstop.com
https://mail.madstop.com/mailman/listinfo/puppet-users

On Sep 27, 2007, at 9:07 AM, <Derek.Whayman@barclayscapital.com> wrote:
> Maybe I should move back towards external node classification ;-)
This, and the thousand or so problems that are like it, are a big  
part of why we''re moving toward external nodes.

That being said, I''ve significantly refactored how this works in the  
current source tree, so there''s a good chance you could get the  
functionality you want if I can finish this xmlrpc => rest  
conversion.  I''m actually doing all class and node evaluation via  
resources, so you could do something like:

if defined(Class[myclass]) { ... }

  --
  A gentleman is a man who can play the accordion but doesn''t. --  
Unknown
  ---------------------------------------------------------------------
  Luke Kanies | http://reductivelabs.com | http://madstop.com