Puppet users - Aug 2013 - if defined not working when class is enlcosed within Class[ ]

Hi,

I am learning puppet using version 2.7.18 on a fresh ubuntu install.

I am trying to test this module 
https://github.com/liamjbennett/puppet-sabnzbd/blob/master/manifests/init.ppbut
I''m having trouble with the
if defined(Class[''supervisor::service'']) section in that it
doesn''t get run
even though the supervisor module is installed.

If i put "else{ notice("supervisor not defined?") }" on the
end then I see
that notice msg in the ''puppet apply --debug'' output.

This supervisor module is downloaded/installed OK from Puppet Forge and if 
I either 

a) comment out the ''if defined'' then it works as expected 
b) *change the if *defined(Class[''supervisor::service'']) to
read if defined(
''supervisor::service'') then it also works as expected.

As you can see there is an "include supervisor" at top of the class
which
I''m guessing isn''t being called in the 
order needed for the ''if defined'' to work and the one without
the Class[ ]
must work because puppet auto loads the modules from the modulepath
and checks if that namespace and module exist?

This is all new to me so i could be very wrong but can anyone explain given 
that init.pp why the ''if defined'' isn''t working and
what is the best
way to achieve what the ''if defined'' is there for and
that''s to see if the
supervisor module is installed/loaded before entering the if statement and 
using the module?

Many thanks for reading
fLo



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So, I can''t speak to the authors intentions, but I''ll do my
best to explain
the behavior.

As you guessed defined() behaves differently based on what is passed to it. 
If passed a resource reference, as it is in the module, it will check that 
that resource has been declared. if passed a string, it will treat it as a 
type/class name and make sure that the resource has been defined. So, as 
written, it''s checking if a class by the name of supervisor::service
has
been declared, while the way you write it, it check if anything by the name 
of supervisor::service has been defined.

The ''include supervisor'' you noticed does nothing regarding
this error, as
the type in question is supervisor::service.

If I had to guess, at one point in the past, supervisor::service was a 
class, while it is now a defined type, and the module you''re working
with
hasn''t updated or something.

On Monday, August 19, 2013 8:33:09 AM UTC-7, Florian Gray Jones
wrote:
>
> Hi,
>
> I am learning puppet using version 2.7.18 on a fresh ubuntu install.
>
> I am trying to test this module 
>
https://github.com/liamjbennett/puppet-sabnzbd/blob/master/manifests/init.ppbut
I''m having trouble with the
> if defined(Class[''supervisor::service'']) section in that
it doesn''t get
> run even though the supervisor module is installed.
>
> If i put "else{ notice("supervisor not defined?") }" on
the end then I see
> that notice msg in the ''puppet apply --debug'' output.
>
> This supervisor module is downloaded/installed OK from Puppet Forge and 
> if I either 
>
> a) comment out the ''if defined'' then it works as expected
> b) *change the if *defined(Class[''supervisor::service''])
to read if
> defined(''supervisor::service'') then it also works as
expected.
>
> As you can see there is an "include supervisor" at top of the
class which
> I''m guessing isn''t being called in the 
> order needed for the ''if defined'' to work and the one
without the Class[] must work because puppet auto loads the modules from the
modulepath
> and checks if that namespace and module exist?
>
> This is all new to me so i could be very wrong but can anyone explain 
> given that init.pp why the ''if defined'' isn''t
working and what is the best
> way to achieve what the ''if defined'' is there for and
that''s to see if the
> supervisor module is installed/loaded before entering the if statement and 
> using the module?
>
> Many thanks for reading
> fLo
>
>
>
>
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ok, that''s great. Thanks for the help.

The puppet-docs it says: "*Modules are how Puppet finds the classes and 
types it can use* — it automatically loads any
class<http://docs.puppetlabs.com/puppet/2.7/reference/lang_classes.html>
 or defined
type<http://docs.puppetlabs.com/puppet/2.7/reference/lang_defined_types.html>
stored
in its modules."

With this in mind, if "*if *defined(Class[ ])" checks for classes..
and in
my case ''supervisor::service'' is as you mentioned not a class
but a define.
Is there an equivalent like "if defined(Define[ ])" or is best
practice to
continue using "if defined(''supervisor::service'')"
to just check for
anything of that name.

Thanks again
fLo



On Monday, 19 August 2013 23:33:09 UTC+8, Florian Gray Jones
wrote:
>
> Hi,
>
> I am learning puppet using version 2.7.18 on a fresh ubuntu install.
>
> I am trying to test this module 
>
https://github.com/liamjbennett/puppet-sabnzbd/blob/master/manifests/init.ppbut
I''m having trouble with the
> if defined(Class[''supervisor::service'']) section in that
it doesn''t get
> run even though the supervisor module is installed.
>
> If i put "else{ notice("supervisor not defined?") }" on
the end then I see
> that notice msg in the ''puppet apply --debug'' output.
>
> This supervisor module is downloaded/installed OK from Puppet Forge and 
> if I either 
>
> a) comment out the ''if defined'' then it works as expected
> b) *change the if *defined(Class[''supervisor::service''])
to read if
> defined(''supervisor::service'') then it also works as
expected.
>
> As you can see there is an "include supervisor" at top of the
class which
> I''m guessing isn''t being called in the 
> order needed for the ''if defined'' to work and the one
without the Class[] must work because puppet auto loads the modules from the
modulepath
> and checks if that namespace and module exist?
>
> This is all new to me so i could be very wrong but can anyone explain 
> given that init.pp why the ''if defined'' isn''t
working and what is the best
> way to achieve what the ''if defined'' is there for and
that''s to see if the
> supervisor module is installed/loaded before entering the if statement and 
> using the module?
>
> Many thanks for reading
> fLo
>
>
>
>
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Since in this case, it''s checking that supervisor::service exists so it
can
declare one, I''d say checking for just
''supervisor::service'' would be fine.
You may want to stay around and see what other people think though, as I 
could be missing something.

Looking at it again, the check to see if a class has been declared seems 
really odd... and testing it now that I have a second, it doesn''t
actually
seem to work at all. I''m not sure how idiomatic that is, or was, but
maybe
someone else can shed some light on it.

On Monday, August 19, 2013 8:32:39 PM UTC-7, Florian Gray Jones
wrote:
>
> ok, that''s great. Thanks for the help.
>
> The puppet-docs it says: "*Modules are how Puppet finds the classes
and
> types it can use* — it automatically loads any
class<http://docs.puppetlabs.com/puppet/2.7/reference/lang_classes.html>
>  or defined
type<http://docs.puppetlabs.com/puppet/2.7/reference/lang_defined_types.html>
stored
> in its modules."
>
> With this in mind, if "*if *defined(Class[ ])" checks for
classes.. and
> in my case ''supervisor::service'' is as you mentioned not
a class but a
> define. Is there an equivalent like "if defined(Define[ ])" or is
best
> practice to continue using "if
defined(''supervisor::service'')" to just
> check for anything of that name.
>
> Thanks again
> fLo
>
>
>
> On Monday, 19 August 2013 23:33:09 UTC+8, Florian Gray Jones wrote:
>>
>> Hi,
>>
>> I am learning puppet using version 2.7.18 on a fresh ubuntu install.
>>
>> I am trying to test this module 
>>
https://github.com/liamjbennett/puppet-sabnzbd/blob/master/manifests/init.ppbut
I''m having trouble with the
>> if defined(Class[''supervisor::service'']) section in
that it doesn''t get
>> run even though the supervisor module is installed.
>>
>> If i put "else{ notice("supervisor not defined?")
}" on the end then I
>> see that notice msg in the ''puppet apply --debug''
output.
>>
>> This supervisor module is downloaded/installed OK from Puppet Forge and
>> if I either 
>>
>> a) comment out the ''if defined'' then it works as
expected
>> b) *change the if
*defined(Class[''supervisor::service'']) to read if
>> defined(''supervisor::service'') then it also works as
expected.
>>
>> As you can see there is an "include supervisor" at top of the
class which
>> I''m guessing isn''t being called in the 
>> order needed for the ''if defined'' to work and the one
without the Class[] must work because puppet auto loads the modules from the
modulepath
>> and checks if that namespace and module exist?
>>
>> This is all new to me so i could be very wrong but can anyone explain 
>> given that init.pp why the ''if defined''
isn''t working and what is the best
>> way to achieve what the ''if defined'' is there for and
that''s to see if
>> the supervisor module is installed/loaded before entering the if
statement
>> and using the module?
>>
>> Many thanks for reading
>> fLo
>>
>>
>>
>>
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On Monday, August 19, 2013 10:32:39 PM UTC-5, Florian Gray Jones
wrote:
>
> ok, that''s great. Thanks for the help.
>
> The puppet-docs it says: "*Modules are how Puppet finds the classes
and
> types it can use* — it automatically loads any
class<http://docs.puppetlabs.com/puppet/2.7/reference/lang_classes.html>
>  or defined
type<http://docs.puppetlabs.com/puppet/2.7/reference/lang_defined_types.html>
stored
> in its modules."
>
>
Where did you see that?  Although true, it may be a bit misleading to new 
Puppeteers, as "load" in this context does not mean the same thing as 
"declare".  That is, the classes in installed modules are not
automatically
assigned to any node; you must still declare them for the nodes where you 
want them.

 
> With this in mind, if "*if *defined(Class[ ])" checks for
classes.. and
> in my case ''supervisor::service'' is as you mentioned not
a class but a
> define. Is there an equivalent like "if defined(Define[ ])" or is
best
> practice to continue using "if
defined(''supervisor::service'')" to just
> check for anything of that name.
>
>
The expression "defined(Class[<classname>])" checks for the
named class
being already declared for the target node.  The expression 
"defined(<classname>)" on the other hand, checks whether a class
or
resource type is known to Puppet, so that it is *available* to be declared 
for the target node.  The form you suggest,
"defined(Define[<title>])" does
not make sense, but the either the condition 
"defined(Supervisor::Service[''
sabnzbd''])" or the condition "defined
''supervisor::service''" should work,
depending on which you mean (they are not equivalent).

Now, having said all that, I leave you with one more piece of advice:
don''t
do it.  The usual use of the defined() function, wherein its argument is a 
resource reference, introduce a parse-order dependency into your manifest 
set, and that''s bad news for you.  The other form, where you test for a
class or resource type being available, is less problematic, but usually 
not what you want.  It is rarely the case that the desired response to a 
resource type or class being undefined is anything other than catalog 
compilation failure, and you don''t need defined() for that.


John

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