RFC 59: Load Ohai pluginstm/ohai_plugins_2

This adds a new phase in the compilation of the run context.

Signed-off-by: Thom May <thom@chef.io>

6 files changed, 93 insertions, 1 deletions

diff --git a/Gemfile.lock b/Gemfile.lock
index 4482a7b5ad..1c7e8bf277 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -37,7 +37,7 @@ GIT
 
 GIT
   remote: https://github.com/chef/ohai.git
-  revision: 6bb6e8cf30118b104dbcffaea17ffb1644aee2cc
+  revision: daeb73c1089d8b611bc5fde3bfddddad28f304eb
   specs:
     ohai (13.0.0)
       chef-config (>= 12.5.0.alpha.1, < 14)
diff --git a/chef-config/lib/chef-config/config.rb b/chef-config/lib/chef-config/config.rb
index b4bb6b76ab..57f55fdce4 100644
--- a/chef-config/lib/chef-config/config.rb
+++ b/chef-config/lib/chef-config/config.rb
@@ -450,6 +450,10 @@ module ChefConfig
     # most of our testing scenarios)
     default :minimal_ohai, false
 
+    # When consuming Ohai plugins from cookbook segments, we place those plugins in this directory.
+    # Subsequent chef client runs will wipe and re-populate the directory to ensure cleanliness
+    default(:ohai_segment_plugin_path) { PathHelper.join(config_dir, "ohai", "cookbook_plugins") }
+
     ###
     # Policyfile Settings
     #
diff --git a/lib/chef/event_dispatch/base.rb b/lib/chef/event_dispatch/base.rb
index 926bbe24b5..0f8013f114 100644
--- a/lib/chef/event_dispatch/base.rb
+++ b/lib/chef/event_dispatch/base.rb
@@ -195,6 +195,22 @@ class Chef
       def lwrp_load_complete
       end
 
+      # Called when an ohai plugin file loading starts
+      def ohai_plugin_load_start(file_count)
+      end
+
+      # Called when an ohai plugin file has been loaded
+      def ohai_plugin_file_loaded(path)
+      end
+
+      # Called when an ohai plugin file has an error on load.
+      def ohai_plugin_file_load_failed(path, exception)
+      end
+
+      # Called when an ohai plugin file loading has finished
+      def ohai_plugin_load_complete
+      end
+
       # Called before attribute files are loaded
       def attribute_load_start(attribute_file_count)
       end
diff --git a/lib/chef/node.rb b/lib/chef/node.rb
index 92bdb5887b..549bde0dbb 100644
--- a/lib/chef/node.rb
+++ b/lib/chef/node.rb
@@ -338,6 +338,10 @@ class Chef
       automatic[:platform_version] = version
     end
 
+    def consume_ohai_data(ohai_data)
+      self.automatic_attrs = Chef::Mixin::DeepMerge.merge(automatic_attrs, ohai_data)
+    end
+
     # Consumes the combined run_list and other attributes in +attrs+
     def consume_attributes(attrs)
       normal_attrs_to_merge = consume_run_list(attrs)
diff --git a/lib/chef/run_context/cookbook_compiler.rb b/lib/chef/run_context/cookbook_compiler.rb
index 94635be03d..02ee2e3519 100644
--- a/lib/chef/run_context/cookbook_compiler.rb
+++ b/lib/chef/run_context/cookbook_compiler.rb
@@ -57,6 +57,7 @@ class Chef
 
       # Run the compile phase of the chef run. Loads files in the following order:
       # * Libraries
+      # * Ohai
       # * Attributes
       # * LWRPs
       # * Resource Definitions
@@ -69,6 +70,7 @@ class Chef
       # #cookbook_order for more information.
       def compile
         compile_libraries
+        compile_ohai_plugins
         compile_attributes
         compile_lwrps
         compile_resource_definitions
@@ -101,6 +103,26 @@ class Chef
         @events.library_load_complete
       end
 
+      # Loads Ohai Plugins from cookbooks, and ensure any old ones are
+      # properly cleaned out
+      def compile_ohai_plugins
+        ohai_plugin_count = count_files_by_segment(:ohai)
+        @events.ohai_plugin_load_start(ohai_plugin_count)
+        FileUtils.rm_rf(Chef::Config[:ohai_segment_plugin_path])
+
+        cookbook_order.each do |cookbook|
+          load_ohai_plugins_from_cookbook(cookbook)
+        end
+
+        # Doing a full ohai system check is costly, so only do so if we've loaded additional plugins
+        if ohai_plugin_count > 0
+          ohai = Ohai::System.new.run_additional_plugins(Chef::Config[:ohai_segment_plugin_path])
+          node.consume_ohai_data(ohai)
+        end
+
+        @events.ohai_plugin_load_complete
+      end
+
       # Loads attributes files from cookbooks. Attributes files are loaded
       # according to #cookbook_order; within a cookbook, +default.rb+ is loaded
       # first, then the remaining attributes files in lexical sort order.
@@ -226,6 +248,19 @@ class Chef
         raise
       end
 
+      def load_ohai_plugins_from_cookbook(cookbook_name)
+        target = Chef::Config[:ohai_segment_plugin_path]
+        files_in_cookbook_by_segment(cookbook_name, :ohai).each do |filename|
+          next unless File.extname(filename) == ".rb"
+
+          Chef::Log.debug "Loading Ohai plugin: #{filename} from #{cookbook_name}"
+          target_name = File.join(target, cookbook_name.to_s, File.basename(filename))
+
+          FileUtils.mkdir_p(File.dirname(target_name))
+          FileUtils.cp(filename, target_name)
+        end
+      end
+
       def load_resource_definitions_from_cookbook(cookbook_name)
         files_in_cookbook_by_segment(cookbook_name, :definitions).each do |filename|
           begin
diff --git a/spec/integration/client/client_spec.rb b/spec/integration/client/client_spec.rb
index 2a31638c0f..1cd74a6fd1 100644
--- a/spec/integration/client/client_spec.rb
+++ b/spec/integration/client/client_spec.rb
@@ -465,6 +465,39 @@ end
     end
   end
 
+  when_the_repository "has a cookbook with an ohai plugin" do
+    before do
+      file "cookbooks/x/recipes/default.rb", <<-RECIPE
+file #{path_to('tempfile.txt').inspect} do
+  content node["english"]["version"]
+end
+      RECIPE
+
+      file "cookbooks/x/ohai/english.rb", <<-OHAI
+        Ohai.plugin(:English) do
+          provides 'english'
+
+          collect_data do
+            english Mash.new
+            english[:version] = "2014"
+          end
+        end
+      OHAI
+
+      file "config/client.rb", <<EOM
+local_mode true
+cookbook_path "#{path_to('cookbooks')}"
+EOM
+    end
+
+    it "should run the ohai plugin" do
+      result = shell_out("#{chef_client} -l debug -c \"#{path_to('config/client.rb')}\" -o 'x::default' --no-fork", :cwd => chef_dir)
+      result.error!
+
+      expect(IO.read(path_to("tempfile.txt"))).to eq("2014")
+    end
+  end
+
   # Fails on appveyor, but works locally on windows and on windows hosts in Ci.
   context "when using recipe-url", :skip_appveyor do
     before(:each) do