[chef] Re: Re: Re: Programmatic creation/deletion of resources

[Daniel DeLeo < >]

On Thursday, May 7, 2015 at 8:58 AM, Simon Detheridge wrote:

> ----- On 7 May, 2015, at 16:23, Daniel DeLeo 
> 
 
>  
> (mailto:
 )
>  wrote:
> > What do you imagine create_source does? Creates a resource with the 
> > resource
> > attributes filled out from the node attributes? That can be accomplished 
> > by
> > writing a ruby module with a method, like
> > https://gist.github.com/danielsdeleo/d4511904a41a9a682c04
>  
>  
>  
> Thanks, that is very much what I'm looking for.  
>  
> Follow-up: My resource has a fairly large number of potential attributes. 
> Is there a way I can set them in a less DSL-like way? For example:
>  
> nxlog_source "name" do
> {"hash": "with", "a": "bunch", "of": "pairs"}.each_pair do |k,v|
> set_attribute k, v
> end
> end
>  
> as opposed to  
>  
> resource_attr1 node_attrs["resource_attr1"]
> ...
> resource_attr50 node_attrs["resource_attr50"]
>  
> This way I can not repeat myself and avoid having to maintain a file with 
> another list of my resource attributes...
You can use Ruby’s #public_send method to call methods that you don’t know 
the name of ahead of time. (There is also #send, but that can call private 
methods, so you shouldn’t use it unless you really have to).

http://ruby-doc.org/core-2.1.1/Object.html#method-i-public_send
  
>  
>  
> > > - How do I enumerate currently-extant resources so that I can delete 
> > > ones that
> > > have been removed? (or... is this even possible?)
> > >  
> > > for example: If I've removed an element from the 'sources' array how 
> > > can I
> > > ensure that the resource's config file is cleaned up on the node?
> >  
>  
>  
>  
> > What thing on the system represents the stuff that exists? Are these 
> > individual
> > files (sounds like yes)? As long as there aren’t unmanaged files in that
> > particular directory, you can use Ruby’s Dir.glob to enumerate the 
> > existing
> > files and compare to the list of things you want, and remove the extra
> > elements.
>  
>  
>  
> Yeah, it's files in a conf.d. I think the issue that I'm grappling with is 
> that let's say someone has used node attributes to create a source, but 
> elsewhere someone has used a lwrp to create a different source in another 
> recipe... How can I ensure I don't clean up the source that's been defined 
> via the lwrp instead of the node attributes?
You can’t do it perfectly in all cases, but if all changes to files in that 
dir occur via core chef resources (file, template, etc.) then you can inspect 
the resource collection to find orphaned files. The “zap” cookbook does this, 
you can maybe use it directly or read the code for inspiration: 
https://github.com/nvwls/zap

>  
> Thanks,
>  
> --  
> Simon Detheridge - CTO, Widgit Software
> 26 Queen Street, Cubbington, CV32 7NA - Tel: +44 (0)1926 333680



--  
Daniel DeLeo