puppet-custom-provider.rb

# Information taken from the book 'Puppet Types and Providers'

Puppet::Type.type(:customtype).provide(
  :customprovider,
  :parent => Puppet::Provider::CustomProvider
) do

  # Automagically generates getter and setter for each resource property
  mk_resource_methods

  def initialize(value={})
    super(value)
    @property_flush = {}
  end

  # Prefetch all instances of a resource
  def self.prefetch(resources)
    # resources parameter is an hash of resources managed by Puppet (catalog)
    resource_instances = instances
    resources.keys.each do |name|
      if provider = resource_instances.find{ |r| r.name == name }
        r[name].provider = provider
      end
    end
  end

  # Discover and return all instances of the resource found on the system
  # Only called when purging resources OR by prefetch
  def self.instances
    resources = Array.new
    resources << new (
      :name    => 'resource_name',
      :ensure  => :present,
      :version => '1.0'
    )
    # Return list of resources
    resources
  end

  # Create a resource
  def create
    # Should update @property_hash accordingly
    @property_hash[:ensure] = :present
  end

  # Destroy a resource
  def destroy
    @property_hash.clear
  end

  # Returns True if resource exists
  def exists?
    @property_hash[:ensure] == :present
  end

  # Handle refresh notifications (notify)
  def refresh
    # ...
  end

  # Called once after Puppet creates, destroys or updates a resource
  def flush
    if @property_flush
      # update resource here
      @property_flush = nil
    end
    @property_hash = resource.to_hash
  end

  # Returns a property of the resource
  # Override magic method created by mk_resource_methods
  def version
    @property_hash[:version]
  end

  # Update a property of the resource
  # Override magic method created by mk_resource_methods
  def version=(value)
    @property_hash[:version] = value
    # Store updated properties for flush
    @property_flush[:version] = value
  end

end