On Monday, December 1, 2014 2:21:01 AM UTC-6, Poil wrote:
>
> Hi,
>
> I try to write an autoconfigure module (collectd) that depends on other
> modules included for my node.
>
If you mean you are writing a module containing declarations that are
conditioned on whether other classes or modules have been assigned to the
target node's catalog, then my first and best advice is to abandon that
idea altogether. As a general rule, such declarations do not work reliably
or well because the results of the necessary conditional tests depend on
the order in which they are evaluated relative to other declarations in
other manifests, and that order is very difficult to predict. Instead, use
Hiera or an ENC to dynamically specify the needed classes for each node.
>
> So I've this class autoloaded for all my nodes :
>
In Puppet jargon term "autoloading" refers to the mechanism by which the
catalog compiler locates the manifest file in which the definition of a
given class or defined type resides (supposing that you have followed the
layout conventions that allow it to do so). That doesn't seem to be what
*you* mean by the term, so if your meaning matters to the question then it
would be to your advantage to explain.
>
> class collectd::client::autoconfig {
> require collectd::client
>
> if tagged('apache') {
> require apache
> include collectd::client::plugin::apache
> }
> if tagged('memcached') {
> require memcached
> include collectd::client::plugin::memcached
> }
> (...)
> }
>
> But sometimes, on my old nodes, collectd is manually configured (for an
> historical bad/good reason); so, for my old_node1 I have "include
> collectd::client::plugin::apache" but I don't have the "apache module"
> included; in this case my autoloader will detect the tag "apache" in my
> class "include collectd::client::plugin::*apache*" ...
>
> It does not seem possible to use "::apache" in the tagged function ? Am I
> right ?
> Have you got any idea for my case ? (I can add a parameter to disable my
> autoconfig, but I'm looking for a better solution if it exists.)
>
>
I haven't used tagged() much (or at all, really), but I don't think it does
what you seem to think it does. The docs say it "tells you whether the
current container is tagged with the specified tags", where the usual
meaning of "container" in Puppet is a class, node, or catalog, so that
function will not inform directly about whether a class other than the one
in which the function call appears is tagged with the specified tag.
Because objects inherit tags from their containers, however, it will
indirectly inform about whether the object in which the call appears is
declared by a class bearing the specified tag (recursively). Classes can
be declared multiple times in multiple places, however, so I cannot see how
the function result could fail to be evaluation-order dependent.
In any case, be aware that classes are automatically tagged with every
segment of their own qualified names, so yes, class
collectd::client:plugin::apache will always bear the tags "collectd",
"client", "plugin", and "apache" (among others) as will every object
declared by that class. I wouldn't expect the tagged() function to reject
the tag "::apache", but that particular tag won't be present on any object
unless you've set it explicitly. None of that should not directly affect
class collectd::client::autoconfig, though. The only way it should see a
tag 'apache' is if it is declared within a container bearing that tag. Do
you mean to say that class collectd::client:plugin::apache declares class
collectd::client::autoconfig? If so, why?
John
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