On Oct 14, 2009, at 3:48 PM, R.I.Pienaar wrote:
>
> hello,
>
> ----- "Luke Kanies" <[email protected]> wrote:
>
>> The solution Arri recommends is what I would also recommend -
>> something akin to his extlookup function, or the datalookup
>> function I
>>
>
> there are two domains of problem here.
>
> - Configuring the behavior of a module
> - Extending the behavior of an existing module.
>
> For the first, use extlookup without question.
>
> The second is more complex, here's a use case.
>
> I found a openvpn module on the net - perhaps from the puppet common
> modules project - and its a good fit, its configurable using
> extlookup so i can adjust the outcome of the stuff it already knows
> how to configure.
>
> Now I build 10 machines but I have new needs, I really need
> openvpn::config to do more, it needs to put new files down - perhaps
> the existing module doesn't support per client configs (called ccd
> in openvpn).
>
> now there might be a relationship between openvpn::install, ::config
> and ::service and my new code really should *plug into* ::config.
>
> I really would want to put my new config files in openvpn::config
> without changing the relationships or the existing elegant and
> configurable structure. Perhaps the openvpn::config class already
> retrieves some variables from extlookup and most certainly when I
> extend it I want access to this info.
>
> Today what are my options for possible patterns to achieve this?
> There's none that ticks all the boxes:
>
> - I can make myopenvpn and include ::service, ::config, ::install
> and just add some extra stuff in there myopenvpn perhaps with a few
> before => Class["openvpn::service"]. This doesnt give me access to
> the extlookup data in the class I'd need to go look and do the same
> lookups, etc. It also does rather brutal things to the nice
> relationship models since other cases that require =>
> Class["openvpn::config"] wont have requires on my new extra stuff.
>
> there are more, but you can see the kind of reservations I have to
> them.
>
> How does ruby aproach this problem? Simple.
>
> class String
> def to_whatever
> # new code
> end
> end
>
> Now all my strings have this new ability, sweet and this doesnt
> break anything, no other classes or strings needs to change,
> everything can just use this new "foo".to_whatever method.
>
> What if I could do the same with puppet, open up the class
> openvpn::config, put new "stuff" into it?
>
> class openvpn::config {
> file{"newfile":
> content => template("newfile.erb")
> }
> }
>
> This template would have access to variables set in the super class
> via extlookup I'd simply be extending it.
>
> How to trigger it on a node?
>
> node foo {
> load openvpn::extendedconfig
>
> include openvpn::config
> .
> .
> }
>
> now, openvpn::config would have both the content from common modules
> and my newfile.
>
> Obviously perhaps my suggested syntax is cludgy, I'm more concerned
> about the concept right now than the how.
>
> I think this captures more what the initial poster had in mind.
One of the many undocumented "features" in Puppet:
class foo {
notify { "foo": }
}
class foo {
notify { "bar": }
}
include foo
Works fine. The only caveat is that if you evaluate 'foo' between the
reopening, the added code won't get evaluated.
Does this provide the behaviour you're asking for? Obviously there
are still limitations - your code has to be loaded manually, can't be
in a module with the same name, etc.
--
Criminal: A person with predatory instincts who has not sufficient
capital to form a corporation. --Howard Scott
---------------------------------------------------------------------
Luke Kanies | http://reductivelabs.com | http://madstop.com
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