[chef] Re: Writing a provider

[Daniel DeLeo < >]

On Friday, October 25, 2013 at 1:39 AM, Alexandre Russel wrote:

Hi all, 

 I've read several time the doc an LWRP, but I'm still a bit lost on how to do it. If someone is kind enough to answer a few questions:

- are an instance of a provider created for each resource it processes ?

A provider is created for each action on each resource. Most of the time a resource only has one action, but it can have more, for example `action :enable, :start` on a service is common.

 

- http://docs.opscode.com/lwrp_custom_provider.html :

  * "The load_current_resource method is used to find a resource" => does this mean I have to write this method ? is it called by chef ? 

That depends on what you’re doing. If your LWRP just runs some other chef resources, you don’t need to bother with this at all. If your LWRP is using custom ruby code to modify the system, then you might want to write this. Its purpose is to examine the existing state of the system and populate a resource object with data describing that state.

 

 * "The current_resource method is used to represent a resource " => might be nice to see it in the code snippet, is it the same as @current_resource ?

Yep, this is just an attr_accessor.

 

- where is the normal place to persist downloaded file ?

Chef::Config[:file_cache_path]

 

- is there a way to share state between all resource processing during a chef run:

  foobar "a"

  foobar  "b"

if foobar is supposed doing a long computation can he save it somewhere the first time foobar "a" is processed to be able to reuse it when foobar "b" is processed ?

Depends on what exactly you’re doing. One option is node[:run_state] which is a regular ruby Hash object which is tied to the lifecycle of the chef run.

 

thanks for your time,

Alex

-- 

Daniel DeLeo