Puppet users - Apr 2013 - Scoping of default types & dependency loops

I''m seeing an interesting dependency issue, based on scoping of default
types.
Using 3.1.1  & aware of
http://docs.puppetlabs.com/guides/scope_and_puppet.html#declare-resource-defaults-per-file

Our mongo::repos class is inheriting the File default that is set in the mongo
class.
This leads to a dependency circle, since we''re using the default to set
a require of a package for every file.

:I would have thought the scoping rules would have prevented that from
happening.

(I''ve cut most of the unnecessary stuff.)

The 2 easiest ways to fix this would be to  use yumrepo in the repos function,
or to just put the require parameter on each file, and skip the default.

I''m more interested in why it produced the loop.


#Notes:  repos is a defined class that places a file into the correct place.. 
It isn''t using the yum_repo type for this, yet.

class mongo::repos {
  repos{"10gen":}
}

class mongo ($repl_set=undef) {
  class {''mongo::repos'': stage => first,}
  
  package { "mongo20-10gen-server":
    ensure => installed,
  }

  File {
    require => Package[''mongo20-10gen-server'']
  }

  file { 
    ''/etc/init.d/mongod'':
      ensure  => present,
      mode    => 755,
      owner   => ''root'',
      group   => ''root'',
      source  => ''puppet:///modules/mongo/mongod'',
      require => Package[''mongo20-10gen-server''];
  }
}




Matthew Barr
Technical Architect
E: mbarr@snap-interactive.com
AIM: matthewbarr1
c:  (646) 727-0535

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On Thursday, April 18, 2013 3:44:34 PM UTC-5, Matthew Barr
wrote:
>
> I''m seeing an interesting dependency issue, based on scoping of
default
> types.  
> Using 3.1.1  & aware of 
>
http://docs.puppetlabs.com/guides/scope_and_puppet.html#declare-resource-defaults-per-file
>
> Our mongo::repos class is inheriting the File default that is set in the 
> mongo class. 
> This leads to a dependency circle, since we''re using the default
to set a
> require of a package for every file.
>
> :I would have thought the scoping rules would have prevented that from 
> happening. 
>

As far as I am aware, resource defaults still affect the dynamic scope in 
which they are declared, just as they always have done.  The guide to which 
you referred seems to say that, too.  That means that the defaults you 
declare in class ''mongo'' apply to all resources declared in
that class and
in any classes declared by that class, recursively, modulo parse-order 
issues where the same class is declared in different places.

In your particular case, that means the File defaults you declare in class 
''mongo'' apply in class mongo::repos (which is declared by
class mongo) and
within the defined type instances declared therein.
 
>
> (I''ve cut most of the unnecessary stuff.)
>
> The 2 easiest ways to fix this would be to  use yumrepo in the repos 
> function, or to just put the require parameter on each file, and skip 
> the default.
>
> I''m more interested in why it produced the loop.
>
>
> #Notes:  repos is a defined class that places a file into the correct
place..  It isn''t using the yum_repo type for this, yet.
>
> class mongo::repos {
>   repos{"10gen":}
>
>
You really should use the fully-qualified name of that defined type.  I 
suppose it must be "mongo::repos::repos".  Aside from being safer, it
would
be much clearer.

Anyway, If you don''t want class ''mongo''s file
defaults to apply in this
scope then you could try overriding them here:

File {
  require => undef
}

Alternatively, the file resource(s) declared by mongo::repos::repos can do 
the same thing individually.
 
> }
>
> class mongo ($repl_set=undef) {
>   class {''mongo::repos'': stage => first,}
>   
>   package { "mongo20-10gen-server":
>     ensure => installed,
>   }
>
>   File {
>     require => Package[''mongo20-10gen-server'']
>   }
>
>   file { 
>     ''/etc/init.d/mongod'':
>       ensure  => present,
>       mode    => 755,
>       owner   => ''root'',
>       group   => ''root'',
>       source  => ''puppet:///modules/mongo/mongod'',
>       require => Package[''mongo20-10gen-server''];
>   }
> }
>
>
>
Best, though, might be to refactor class ''mongo'' so that the
scope of the
resource defaults does not include class mongo::repos in the first place.  
For example:

class mongo($repl_set = undef) {
  class { ''mongo::repos'': stage =>
''first'' }
  class { ''mongo::everything_else'': }
}

class mongo::everything_else {
  File {
    require => Package[''mongo20-10gen-server'']
  }

  ...
}


John

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> As far as I am aware, resource defaults still affect the dynamic scope in
which they are declared, just as they always have done.  The guide to which you
referred seems to say that, too.  That means that the defaults you declare in
class ''mongo'' apply to all resources declared in that class
and in any classes declared by that class, recursively, modulo parse-order
issues where the same class is declared in different places.
> 
> In your particular case, that means the File defaults you declare in class
''mongo'' apply in class mongo::repos (which is declared by
class mongo) and within the defined type instances declared therein.
That''s what I was figuring must be happening.  As dig deeper, I keep
trying to get to a better place in my head w/ regard to scoping.  
It''s… interesting sometimes :)

>  
> 
> class mongo::repos {
>   repos{"10gen":} } 
> You really should use the fully-qualified name of that defined type.  I
suppose it must be "mongo::repos::repos".  Aside from being safer, it
would be much clearer.
Actually, the defined type is in it''s own module, repos.  
It''s the only thing in there, and thus, this would be it''s
FQN, wouldn''t it ?

 Class mongo::repos only exists to call it, and move the  
repos{"10gen":} into another stage.   I couldn''t see a way to
do it any other way when I initially set this up.
That was the entirety of the mongo::repos class.


> Anyway, If you don''t want class ''mongo''s file
defaults to apply in this scope then you could try overriding them here:
> 
> File {
>   require => undef
> }
> 
> Alternatively, the file resource(s) declared by mongo::repos::repos can do
the same thing individually.
>  
> 
> Best, though, might be to refactor class ''mongo'' so that
the scope of the resource defaults does not include class mongo::repos in the
first place.  For example:
> 
> class mongo($repl_set = undef) {
>   class { ''mongo::repos'': stage =>
''first'' }
>   class { ''mongo::everything_else'': }
> }
> 
And that''s the way that feels right.    The undef option is hacky.  The
refactor seems to be the more clear & elegant.


So in summary:  3 total hacks,   1 better  answer.


Thanks!



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