Puppet users - Apr 2012 - Optional values from Hiera (no default value)

Hello Puppet List,

I''m writing a module that should take an optional value and I want to
get it (amongst other places) from Hiera.

$repository = $::java_repository ? {
  undef   => hiera(''java_repository'')
  default => $::java_repository,
}

But this fails because Hiera raises an error if it can''t find a value.

I later want to do something like this:

if $repository {
  Class[$repository] -> Class[''java::install'']
}

I tried following the examples from the recent blog series about
module design but I''m still very much learning so this might not even
be the best way to go about this. Any hints would be appreciated.

Cheers,
Lars

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In regard to: [Puppet Users] Optional values from Hiera (no default value),...:
> Hello Puppet List,
>
> I''m writing a module that should take an optional value and I want
to
> get it (amongst other places) from Hiera.
>
> $repository = $::java_repository ? {
>  undef   => hiera(''java_repository'')
>  default => $::java_repository,
> }
hiera() can take a second argument which is the default you want to
supply if no data store provides a value.  Before you ask, no, I don''t
know where that''s documented, but we''ve been using it for a
while in
our puppet manifests and it has been mentioned on the list even today.

Tim
-- 
Tim Mooney                                             Tim.Mooney@ndsu.edu
Enterprise Computing & Infrastructure                  701-231-1076 (Voice)
Room 242-J6, IACC Building                             701-231-8541 (Fax)
North Dakota State University, Fargo, ND 58105-5164

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Hey Tim,

thanks for your answer.
> hiera() can take a second argument which is the default you want to
> supply if no data store provides a value.  Before you ask, no, I
don''t
> know where that''s documented, but we''ve been using it for
a while in
> our puppet manifests and it has been mentioned on the list even today.
I actually knew about that already but if I use that I''ll have to
revert to some "magic" value as the default because it can''t
be nil
for example

I''d have to do hiera(''foo'',
''MAGIC'') and then check for ''MAGIC'' in my
if statement. That''s not a big deal but I had hoped there would be a
way to have a really "optional" lookup.

Cheers,
Lars

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