Puppet users - Nov 2010 - How to use a resource name in its own definition?

Hi, I''m trying to set up Puppet here for the first time and have run
into
some problems.

To set up our users, I''m trying to define many users at once as virtual
resources for later realisation in sets.  However, I''d like to have it
properly create the home directory:

    @user { ''foo'':
        ensure => "present",
        managehome => true,
        home => $operatingsystem ? {
                solaris => "/export/home/foo",
                default => "/home/foo",
        },
     }

Now, this works; what I want to do is to make the ''foo'' bit
parameterised,
so that I can do:

$admins = [ ''foo'', ''bar'' ]
    @user { $admins:
        ensure => "present",
        managehome => true,
        home => $operatingsystem ? {
                solaris => "/export/home/$name",
                default => "/home/$name",
        },
     }

However this doesn''t work; the $name is taken from the class that
we''re
running this in.  Is there any way to do this?  I''d use a loop over the
$admins list, except that I cant find any loop structures in the puppet
config language, only if/else.

I''ve tried using a define to do it:

define users::addVirt() {
    @user { $name:
        ensure => "present",
        managehome => true,
        home => $operatingsystem ? {
                solaris => "/export/home/$name",
                default => "/home/$name",
        },
     }
}
class users {
  $admins = [ ''foo'', ''bar'' ]
  users::addVirt { [  $admins ]: }
}

and this works; however when I later try to realise the users:

class users::admins inherits users {
  $admingroup = $operatingsystem ? {
                solaris => ''sysadmin'',
                default => ''unixadmin''
  }
  User[ $admins ] {
      groups +> [ $admingroup ],
  }
  realize( User[ $admins ] )
}

I end up with:

err: Could not retrieve catalog from remote server: Error 400 on SERVER:
Only subclasses can override parameters at
/etc/puppet/manifests/classes/users.pp:96 on node
secpupprd01.its.auckland.ac.nz

which is complaining about the part:

  User[ $admins ] {
      groups +> [ $admingroup ],
  }

although I cannot see why.

Does anyone have any advice for me on what is going wrong here, or a better
way to achieve this?  Thanks in advance for any help...

Steve

 

Steve Shipway

University of Auckland ITS

UNIX Systems Design Lead

s.shipway@auckland.ac.nz

Ph: +64 9 373 7599 ext 86487

 

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On Nov 3, 4:43 pm, "Steve Shipway" <s.ship...@auckland.ac.nz>
wrote:
> To set up our users, I''m trying to define many users at once as
virtual
> resources for later realisation in sets.  However, I''d like to
have it
> properly create the home directory
[... and]
> I want to [...] make the [username] parameterised
[...]
> I''ve tried using a define to do it:
>
> define users::addVirt() {
>     @user { $name:
>         ensure => "present",
>         managehome => true,
>         home => $operatingsystem ? {
>                 solaris => "/export/home/$name",
>                 default => "/home/$name",
>         },
>      }}
>
> class users {
>   $admins = [ ''foo'', ''bar'' ]
>   users::addVirt { [  $admins ]: }
>
> }
>
> and this works;

As it should.  A define wrapping the resource declaration is just what
you need to use for this purpose.

> however when I later try to realise the users:
>
> class users::admins inherits users {
>   $admingroup = $operatingsystem ? {
>                 solaris => ''sysadmin'',
>                 default => ''unixadmin''
>   }
>   User[ $admins ] {
>       groups +> [ $admingroup ],
>   }
>   realize( User[ $admins ] )
>
> }
>
> I end up with:
>
> err: Could not retrieve catalog from remote server: Error 400 on SERVER:
> Only subclasses can override parameters at
> /etc/puppet/manifests/classes/users.pp:96 on node
> secpupprd01.its.auckland.ac.nz
>
> which is complaining about the part:
>
>   User[ $admins ] {
>       groups +> [ $admingroup ],
>   }
>
> although I cannot see why.
A Puppet define is not a macro.  Roughly speaking, your User resources
do not belong to class users, but rather to instances of your define,
users::addVirt, which is why a subclass of users cannot override their
properties.  You could try nesting the define inside class users, but
I don''t really think that''s gonna work (it would be sweet if
it did,
though!).

More likely, you will either need to enumerate all the users or to
modify your define so that it assigns the needed group(s) at the place
the users are initially declared.  Alternatively, you might be able to
use parameterized classes (new in 2.6.x) instead of defines to do this
job, but I''m not sure offhand how nicely they play with inheritance or
array parameters.


Good Luck,

John

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> A Puppet define is not a macro.  Roughly speaking, your User resources
> do not belong to class users, but rather to instances of your define,
> users::addVirt, which is why a subclass of users cannot override their
> properties.  You could try nesting the define inside class users, but
> I don''t really think that''s gonna work (it would be sweet
if it did,
> though!).
This explains a lot, then.  I was thinking of a define as a macro or a function
block, whereas in fact it is more like a class (albeit with multiple instances).

A parameterised class isn''t going to work.

Maybe I can make users::virt as the define, and then then a subclass
users::virt::admins which inherits users and is included by users::admins in
order to get around this?  I''ll try it and see what it says...

Thanks for the help; in a couple of days the Puppet book should arrive here and
hopefully fill in the large gaps in the online manual for us.

Steve


Steve Shipway
steve@steveshipway.org
Routers2.cgi web frontend for MRTG/RRD; NagEventLog Nagios agent for Windows
Event Log monitoring; check_vmware plugin for VMWare monitoring in Nagios and
MRTG; and other Open Source projects.
Web: http://www.steveshipway.org/software
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