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Bernd Adamowicz

2010-Apr-26 11:24 UTC

[Puppet Users] Resolving variables when using templates

Hi all,

given these two classes inside the file
''/etc/puppet/modules/templates_eval/manifests/init.pp'':

     53 class templates_eval::providevars {
     54 
     55    
$hibernate_connection_dialect="org.hibernate.dialect.Oracle10gDialect"
     56 }
     57 
     58 class templates_eval::testvars {
     59 
     60     include templates_eval::providevars
     61 
     62     file {
     63         "/tmp/tmplteval.properties":
     64             ensure => "present",
     65             mode => 644,
     66             content =>
template("templates_eval/global.properties.erb"),
     67     }
     68 }

The file ''/etc/puppet/manifests/site.pp'' includes class
''templates_eval::testvars'':

     13 node "myhostname.net" {
	...
     17     include templates_eval::testvars
     18 }

This is the content of template
''/etc/puppet/modules/templates_eval/templates/global.properties.erb'':

     12 
     13 domain.suffix=<%= fqdn %>
     14 
     15 hibernate.connection.dialect=<%= hibernate_connection_dialect  %>

However, when running Puppet on a Puppet node, obviously the variable
''$hibernate_connection_dialect'' cannot be resolved:

[root@myhostname puppet]# puppetd -v -d --test
...
err: Could not retrieve catalog from remote server: Error 400 on SERVER: Failed
to parse template templates_eval/global.properties.erb: Could not find value for
''hibernate_connection_dialect'' at
/etc/puppet/modules/templates_eval/manifests/init.pp:64 on node myhostname.net
warning: Not using cache on failed catalog
err: Could not retrieve catalog; skipping run
[root@myhostname puppet]#

Obviously the ''include templates_eval::providevars'' inside
class ''templates_eval::testvars'' has no impact. I tried
several other approaches (importing manifests, etc.), too. But none of them
worked. So the basic question is: How can I have a set of variables defined in
scope X (where X might be a manifest, a class, or a define) and include it into
scope Y (where Y will most likely be a class or maybe a node).

Thanks in advance for any help!
Bernd

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Dan Bode

2010-Apr-26 13:54 UTC

head link

Re: [Puppet Users] Resolving variables when using templates

On Mon, Apr 26, 2010 at 4:24 AM, Bernd Adamowicz <
Bernd.Adamowicz@esailors.de> wrote:
> Hi all,
>
> given these two classes inside the file
> ''/etc/puppet/modules/templates_eval/manifests/init.pp'':
>
>     53 class templates_eval::providevars {
>     54
>     55
>
$hibernate_connection_dialect="org.hibernate.dialect.Oracle10gDialect"
>     56 }
>     57
>
It should work if you just explicitly assign the variable in the scope where
you execute the template function.

>     58 class templates_eval::testvars {
>     59
>     60     include templates_eval::providevars
>     61
>
        61.5
hibernate_connection_dialect=templates_eval::providevars::hibernate_connection_dialect

>     62     file {
>     63         "/tmp/tmplteval.properties":
>     64             ensure => "present",
>     65             mode => 644,
>     66             content =>
> template("templates_eval/global.properties.erb"),
>     67     }
>     68 }
>
> The file ''/etc/puppet/manifests/site.pp'' includes class
> ''templates_eval::testvars'':
>
>     13 node "myhostname.net" {
>        ...
>     17     include templates_eval::testvars
>     18 }
>
> This is the content of template
>
''/etc/puppet/modules/templates_eval/templates/global.properties.erb'':
>
>     12
>     13 domain.suffix=<%= fqdn %>
>     14
>     15 hibernate.connection.dialect=<%= hibernate_connection_dialect 
%>
>
> However, when running Puppet on a Puppet node, obviously the variable
> ''$hibernate_connection_dialect'' cannot be resolved:
>
> [root@myhostname puppet]# puppetd -v -d --test
> ...
> err: Could not retrieve catalog from remote server: Error 400 on SERVER:
> Failed to parse template templates_eval/global.properties.erb: Could not
> find value for ''hibernate_connection_dialect'' at
> /etc/puppet/modules/templates_eval/manifests/init.pp:64 on node
> myhostname.net
> warning: Not using cache on failed catalog
> err: Could not retrieve catalog; skipping run
> [root@myhostname puppet]#
>
> Obviously the ''include templates_eval::providevars''
inside class
> ''templates_eval::testvars'' has no impact. I tried several
other approaches
> (importing manifests, etc.), too. But none of them worked. So the basic
> question is: How can I have a set of variables defined in scope X (where X
> might be a manifest, a class, or a define) and include it into scope Y
> (where Y will most likely be a class or maybe a node).
>
> Thanks in advance for any help!
> Bernd
>
> --
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>
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> .
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> http://groups.google.com/group/puppet-users?hl=en.
>
>
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Mike Pountney

2010-Apr-26 14:07 UTC

head link

Re: [Puppet Users] Resolving variables when using templates

On 26 Apr 2010, at 12:24, Bernd Adamowicz wrote:
> Hi all,
> 
> given these two classes inside the file
''/etc/puppet/modules/templates_eval/manifests/init.pp'':
> 
>     53 class templates_eval::providevars {
>     54 
>     55    
$hibernate_connection_dialect="org.hibernate.dialect.Oracle10gDialect"
>     56 }
>     57 
>     58 class templates_eval::testvars {
>     59 
>     60     include templates_eval::providevars
>     61 
>     62     file {
>     63         "/tmp/tmplteval.properties":
>     64             ensure => "present",
>     65             mode => 644,
>     66             content =>
template("templates_eval/global.properties.erb"),
>     67     }
>     68 }
This will not work as you expect, as the include templates_eval:;providevars
creates a lower scope.

You would need either have the $hiber... variable defined in the
templates_eval::testvars class directly, or inherit the providevars class like:

class templates_eval::testvars inherits templates_eval::providevars {
  ...
}
> 
> Obviously the ''include templates_eval::providevars''
inside class ''templates_eval::testvars'' has no impact. I tried
several other approaches (importing manifests, etc.), too. But none of them
worked. So the basic question is: How can I have a set of variables defined in
scope X (where X might be a manifest, a class, or a define) and include it into
scope Y (where Y will most likely be a class or maybe a node).
> 
Importing a file works at the parsing stage rather than the compilation stage
(where variables are interpreted), so this would also not work as you expect. I
like to thing of the parser/import phase as puppet merging all the *.pp files
into one big PP file, which is then compiled based on the node in question (and
the facts provided by that node). I''m pretty sure something more clever
actually happens, but it''s not a bad place to start for thinking about
how the scope works - import is more like #include in a C preprocessor.





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Bernd Adamowicz

2010-Apr-26 15:51 UTC

head link

AW: [Puppet Users] Resolving variables when using templates

OK. Actually it worked when I added:

$hibernate_connection_dialect=$templates_eval::providevars::hibernate_connection_dialect

This solves the base problem but at the same time creates another one: I do not
have to include variables from only one class but depending one some environment
settings from different classes. Maybe I''ve just picked a completely
wrong approach, so I''d just like to show what I mean with some
(none-Puppet) pseudo code:

If (environment == "envX")
Then
	$hibernate_connection_dialect=$envX::hibernate_connection_dialect
Else if (environment == "envY")
Then
	$hibernate_connection_dialect=$envY::hibernate_connection_dialect
End

But actually I don''t want is to have code like this - the redefinition
of every variable depending on the environment. I was thinking about some kind
of associative array which would allow to iterate over values
''envX'', ''envY'', etc. But again this would
lead to a redefinition and I think Puppet does not have the feature of assoc.
array. (Right?)

Inheritance, as mentioned by Mike, is also not possible since I would then need
some kind of ''dynamic'' inheritance like this (pseudo code
again):

If (environment == "envX")
Then
	class env inhertit $envX::class {

	}
End

Seems this is not possible in Puppet, too. So maybe there''s a
completely different approach in Puppet for accomplishing this problem (?)

Thanks Bernd

>> It should work if you just explicitly assign the variable in the scope
where you execute the template function.
> 
>    58 class templates_eval::testvars {
>    59
>    60     include templates_eval::providevars
>    61
>       
>>        61.5
hibernate_connection_dialect=templates_eval::providevars::hibernate_connection_dialect
> 
>    62     file {
>    63         "/tmp/tmplteval.properties":
>    64             ensure => "present",
>    65             mode => 644,
>    66             content =>
template("templates_eval/global.properties.erb"),
>    67     }
>    68 }

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Dan Bode

2010-Apr-26 17:50 UTC

head link

Re: [Puppet Users] Resolving variables when using templates

On Mon, Apr 26, 2010 at 8:51 AM, Bernd Adamowicz <
Bernd.Adamowicz@esailors.de> wrote:
> OK. Actually it worked when I added:
>
>
>
$hibernate_connection_dialect=$templates_eval::providevars::hibernate_connection_dialect
>
> This solves the base problem but at the same time creates another one: I do
> not have to include variables from only one class but depending one some
> environment settings from different classes. Maybe I''ve just
picked a
> completely wrong approach, so I''d just like to show what I mean
with some
> (none-Puppet) pseudo code:
>
> If (environment == "envX")
> Then
>        $hibernate_connection_dialect=$envX::hibernate_connection_dialect
> Else if (environment == "envY")
> Then
>        $hibernate_connection_dialect=$envY::hibernate_connection_dialect
> End
>
>this type of conditional logic looks like its better suited to be set in an
external node classifier. This allows you to specify an external script that
classfies nodes (sets top scope params and classes) based on external
information about that node. This is best implemented using some kind of
inheritance structure that supports overriding of parameters. Variables set
at top scope will be available by their non fully qualified names in all
scopes (unless they are overridden by a local scope).  The puppet dashboard
is an implementation of the inheritence driven parameterization of nodes
(called groups).

I actually like the approach of having a MODULE::params class for
parmeterizations that can be handled internally. But for things that need to
be specified by some external categorization of machines, its best to use an
external node classifier to support a more data driven parameterization of
classes.


> But actually I don''t want is to have code like this - the
redefinition of
> every variable depending on the environment. I was thinking about some kind
> of associative array which would allow to iterate over values
''envX'',
> ''envY'', etc. But again this would lead to a redefinition
and I think Puppet
> does not have the feature of assoc. array. (Right?)
>
not yet, this will be supported in Rwolf, but I dont think that would be the
best way to solve you problem.
>
> Inheritance, as mentioned by Mike, is also not possible since I would then
> need some kind of ''dynamic'' inheritance like this (pseudo
code again):
>
> If (environment == "envX")
> Then
>        class env inhertit $envX::class {
>
>        }
> End
>
> Seems this is not possible in Puppet, too. So maybe there''s a
completely
> different approach in Puppet for accomplishing this problem (?)
>
> Thanks Bernd
>
>
> >> It should work if you just explicitly assign the variable in the
scope
> where you execute the template function.
> >
> >    58 class templates_eval::testvars {
> >    59
> >    60     include templates_eval::providevars
> >    61
> >
> >>        61.5
>
hibernate_connection_dialect=templates_eval::providevars::hibernate_connection_dialect
> >
> >    62     file {
> >    63         "/tmp/tmplteval.properties":
> >    64             ensure => "present",
> >    65             mode => 644,
> >    66             content =>
> template("templates_eval/global.properties.erb"),
> >    67     }
> >    68 }
>
>
> --
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>
>
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Bernd Adamowicz

2010-Apr-27 08:33 UTC

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AW: [Puppet Users] Resolving variables when using templates

Dan, I think what you suggested seems to be the right way. I had a deeper look
at external node classifiers as well as on working with different environments
inside Puppet. I have not been aware of these concepts but will start now to
create a proof of concept for our systems.

Thanks all for helping!

Bernd


> this type of conditional logic looks like its better suited to be set in an
external node classifier. This allows you to specify an external script >
> that classfies nodes (sets top scope params and classes) based on external
information about that node. This is best implemented using some kind of >
> inheritance structure that supports overriding of parameters. Variables set
at top scope will be available by their non fully qualified names in all >
> scopes (unless they are overridden by a local scope).  The puppet dashboard
is an implementation of the inheritence driven parameterization of nodes >
> (called groups).
>
> I actually like the approach of having a MODULE::params class for
parmeterizations that can be handled internally. But for things that need to be
> > > specified by some external categorization of machines, its best
to use an external node classifier to support a more data driven
parameterization of > > classes.
> more options, visit this group at
http://groups.google.com/group/puppet-users?hl=en.
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Puppet users - Apr 2010 - Resolving variables when using templates

[Puppet Users] Resolving variables when using templates

Re: [Puppet Users] Resolving variables when using templates

Re: [Puppet Users] Resolving variables when using templates

AW: [Puppet Users] Resolving variables when using templates

Re: [Puppet Users] Resolving variables when using templates

AW: [Puppet Users] Resolving variables when using templates