[chef] Re: Re: Re: validation of attributes that can't have a sensible default

[Peter Donald < >]

Hi,

I don't have the code in front of me but I think that in another
cookbook we add a snippet in a library file that looks something like

class Object
  clazz = ::RealityForge::AttributeTools
  clazz.public_methods.each do |m|
    unless respond_to?(m)
      define_method(m){p clazz.send(m)}
    end
  end
end

It is ugly and dangerous so don't do this at home ;)


On Thu, Oct 24, 2013 at 9:20 PM, Sölvi Páll Ásgeirsson 
<
 >
 wrote:
> Out of curiosity, what is the ruby trickery you use to shorten the method
> name?
>
> Cheers,
> Sölvi
>
>
> On Thu, Oct 24, 2013 at 9:34 AM, Sölvi Páll Ásgeirsson 
> <
 >
> wrote:
>>
>> Thanks Peter, this helps alot.
>>
>> Cheers
>> Sölvi
>>
>>
>> On Thu, Oct 24, 2013 at 12:12 AM, Peter Donald 
>> <
 >
>> wrote:
>>>
>>> Hi,
>>>
>>> We actually have a bunch of approaches to address this problem.
>>> However our favourite one is to use the "cutlery" helper cookbook [1]
>>> and add snippets of code like
>>>
>>> # Check that the attribute node["foo"]["bar"]["baz"]["myattr"] exists
>>> and is a string and return it
>>> myattr = RealityForge::AttributeTools.ensure_attribute(node,
>>> "foo.bar.baz.myattr", String)
>>> # Check that the attribute node["foo"]["mOtherAttr"] exists and return it
>>> myOtherAttr = RealityForge::AttributeTools.ensure_attribute(node,
>>> "foo.mOtherAttr")
>>>
>>> We can also use the same approach to check contents of databags (pass
>>> databag as first parameter). Of course
>>> "RealityForge::AttributeTools.ensure_attribute" is really long so we
>>> tend to shorten it to "ensure_attribute" via some ruby trickery.
>>>
>>> HTH
>>>
>>> [1] https://github.com/realityforge/chef-cutlery
>>>
>>> On Thu, Oct 24, 2013 at 7:39 AM, Sölvi Páll Ásgeirsson 
>>> <
 >
>>> wrote:
>>> > Hello everyone
>>> >
>>> > For some cookbook attributes, you can not set a sensible default.
>>> >
>>> > What i'm doing now is setting the attribute defaults to nil and
>>> > creating a
>>> > _attribute_validation.rb recipe which is basically a sequence of:
>>> >
>>> > unless foo[:attr]
>>> >   Chef::Application.fatal! "foo[:attr] is unset.  Override with sane
>>> > values
>>> > of bar"
>>> > end
>>> >
>>> > This is repetitive and boring.  Is there a smarter way of going about
>>> > this
>>> > which I'm missing?
>>> > Is there a way to do this directly from the attributes/*.rb ?
>>> >
>>> > Thanks alot!
>>> >
>>> > Sölvi Páll Á
>>>
>>>
>>>
>>> --
>>> Cheers,
>>>
>>> Peter Donald
>>
>>
>



-- 
Cheers,

Peter Donald