On Tuesday, August 7, 2012 1:25:32 PM UTC-5, Douglas wrote:
>
> As usual, I'm confused about scope in puppet. This puppet 2.7.1.
>
> In my classes below, the bottom class, company::web::content, requires
> the file resource '/usr/local/company'. However, that resource is
> defined two includes back in the class company::common. I always
> thought this wasn't supposed to work, and that you could only access
> the immediate scope, not the scope of stuff beyond this. It does work
> however. Is it supposed to. Why?
>
Yes, it is supposed to. All classes and resources have global scope once
they are declared. The 'include' function does not introduce classes and
their resources into the current, innermost scope -- it doesn't need to do
so, and couldn't even if it wanted to do. Instead, 'include' ensures that
the specified class has been parsed and added to the catalog, which, as I
said, puts them into the global scope.
The model pretty much has to work that way, because the physical resources
of the target node all have global scope, too.
It is useful and appropriate for classes and definitions to 'include' (or
'require') the classes on which they rely, provided that those classes are
not parametrized (Puppet <= 2.7.x). Aside from it's plain aggregation
function, that way it's a lot easier to make classes independent of the
order in which they are declared, plus it has documentary value. Classes
that 'include' all the classes on which they directly rely are more robust.
However, there is no requirement for a class to 'include' its
dependencies. If a class does not do so, then it simply relies on those
dependencies to have been declared by some other class that was parsed
before it. Users of parametrized classes rely heavily on this, because
parametrized classes can be declared only once, but they may need to be
referenced by many other classes.
John
>
>
> class company::common {
> file {
> '/usr/local/company':
> ....
> }
> }
>
>
> class company::web::common {
> include company::common
> }
>
>
> class company::web::content {
> include company::web::common
>
> file {
> '/usr/local/company/www':
> require => File['/usr/local/company']
> }
> }
>
> Doug.
>
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