1 files changed, 137 insertions, 0 deletions
diff --git a/lib/chef/resource_builder.rb b/lib/chef/resource_builder.rb
new file mode 100644
index 0000000000..bb0962d128
--- /dev/null
+++ b/lib/chef/resource_builder.rb
@@ -0,0 +1,137 @@
+#
+# Author:: Lamont Granquist (<lamont@chef.io>)
+# Copyright:: Copyright (c) 2015 Opscode, Inc.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# NOTE: this was extracted from the Recipe DSL mixin, relevant specs are in spec/unit/recipe_spec.rb
+
+class Chef
+  class ResourceBuilder
+    attr_reader :type
+    attr_reader :name
+    attr_reader :created_at
+    attr_reader :params
+    attr_reader :run_context
+    attr_reader :cookbook_name
+    attr_reader :recipe_name
+    attr_reader :enclosing_provider
+    attr_reader :resource
+
+    # FIXME (ruby-2.1 syntax): most of these are mandatory
+    def initialize(type:nil, name:nil, created_at: nil, params: nil, run_context: nil, cookbook_name: nil, recipe_name: nil, enclosing_provider: nil)
+      @type               = type
+      @name               = name
+      @created_at         = created_at
+      @params             = params
+      @run_context        = run_context
+      @cookbook_name      = cookbook_name
+      @recipe_name        = recipe_name
+      @enclosing_provider = enclosing_provider
+    end
+
+    def build(&block)
+      raise ArgumentError, "You must supply a name when declaring a #{type} resource" if name.nil?
+
+      @resource = resource_class.new(name, run_context)
+      resource.source_line = created_at
+      resource.declared_type = type
+
+      # If we have a resource like this one, we want to steal its state
+      # This behavior is very counter-intuitive and should be removed.
+      # See CHEF-3694, https://tickets.opscode.com/browse/CHEF-3694
+      # Moved to this location to resolve CHEF-5052, https://tickets.opscode.com/browse/CHEF-5052
+      if prior_resource
+        resource.load_from(prior_resource)
+      end
+
+      resource.cookbook_name = cookbook_name
+      resource.recipe_name = recipe_name
+      # Determine whether this resource is being created in the context of an enclosing Provider
+      resource.enclosing_provider = enclosing_provider
+
+      # XXX: this is required for definition params inside of the scope of a
+      # subresource to work correctly.
+      resource.params = params
+
+      # Evaluate resource attribute DSL
+      resource.instance_eval(&block) if block_given?
+
+      # emit a cloned resource warning if it is warranted
+      if prior_resource
+        if is_trivial_resource?(prior_resource) && identicalish_resources?(prior_resource, resource)
+          emit_harmless_cloning_debug
+        else
+          emit_cloned_resource_warning
+        end
+      end
+
+      # Run optional resource hook
+      resource.after_created
+
+      resource
+    end
+
+    private
+
+    def resource_class
+      # Checks the new platform => short_name => resource mapping initially
+      # then fall back to the older approach (Chef::Resource.const_get) for
+      # backward compatibility
+      @resource_class ||= Chef::Resource.resource_for_node(type, run_context.node)
+    end
+
+    def is_trivial_resource?(resource)
+      identicalish_resources?(resource_class.new(name, run_context), resource)
+    end
+
+    # this is an equality test specific to checking for 3694 cloning warnings
+    def identicalish_resources?(first, second)
+      skipped_ivars = [ :@source_line, :@cookbook_name, :@recipe_name, :@params, :@elapsed_time, :@declared_type ]
+      checked_ivars = ( first.instance_variables | second.instance_variables ) - skipped_ivars
+      non_matching_ivars = checked_ivars.reject do |iv|
+        if iv == :@action && ( [first.instance_variable_get(iv)].flatten == [:nothing] || [second.instance_variable_get(iv)].flatten == [:nothing] )
+          # :nothing action on either side of the comparison always matches
+          true
+        else
+          first.instance_variable_get(iv) == second.instance_variable_get(iv)
+        end
+      end
+      Chef::Log.debug("ivars which did not match with the prior resource: #{non_matching_ivars}")
+      non_matching_ivars.empty?
+    end
+
+    def emit_cloned_resource_warning
+      Chef::Log.warn("Cloning resource attributes for #{resource} from prior resource (CHEF-3694)")
+      Chef::Log.warn("Previous #{prior_resource}: #{prior_resource.source_line}") if prior_resource.source_line
+      Chef::Log.warn("Current  #{resource}: #{resource.source_line}") if resource.source_line
+    end
+
+    def emit_harmless_cloning_debug
+      Chef::Log.debug("Harmless resource cloning from #{prior_resource}:#{prior_resource.source_line} to #{resource}:#{resource.source_line}")
+    end
+
+    def prior_resource
+      @prior_resource ||=
+        begin
+          key = "#{type}[#{name}]"
+          prior_resource = run_context.resource_collection.lookup(key)
+        rescue Chef::Exceptions::ResourceNotFound
+          nil
+        end
+    end
+
+  end
+end