Ohai::Runner class for running plugins, add run_plugins to Ohai::System to run loaded plugins

5 files changed, 122 insertions, 15 deletions

diff --git a/lib/ohai/plugins/chef.rb b/lib/ohai/plugins/chef.rb
index b9b6872e..bbe16b46 100644
--- a/lib/ohai/plugins/chef.rb
+++ b/lib/ohai/plugins/chef.rb
@@ -19,7 +19,7 @@
 require 'chef/version'
 
 Ohai.plugin do
-  provides "chef"
+  provides "chef_packages/chef"
 
   collect_data do
     self[:chef_packages] = Mash.new unless self[:chef_packages]
diff --git a/lib/ohai/plugins/darwin/kernel.rb b/lib/ohai/plugins/darwin/kernel.rb
index ff8633aa..14f8bf6d 100644
--- a/lib/ohai/plugins/darwin/kernel.rb
+++ b/lib/ohai/plugins/darwin/kernel.rb
@@ -17,7 +17,8 @@
 #
 
 Ohai.plugin do
-  provides "kernel"
+  provides "kernel/os", "kernel/machine", "kernel/modules"
+  depends "kernel/name"
 
   collect_data do
     kernel[:os] = kernel[:name]
diff --git a/lib/ohai/plugins/kernel.rb b/lib/ohai/plugins/kernel.rb
index bfadcda0..a3f508f4 100644
--- a/lib/ohai/plugins/kernel.rb
+++ b/lib/ohai/plugins/kernel.rb
@@ -18,8 +18,9 @@
 
 Ohai.plugin do
   provides "kernel"
+  provides "kernel/name", "kernel/release", "kernel/version", "kernel/machine", "kernel/modules"
 
-  depends 'ruby'
+  depends "languages/ruby"
 
   collect_data do
     kernel Mash.new
diff --git a/lib/ohai/runner.rb b/lib/ohai/runner.rb
new file mode 100644
index 00000000..84d53e48
--- /dev/null
+++ b/lib/ohai/runner.rb
@@ -0,0 +1,93 @@
+#
+# Author:: Claire McQuin (<claire@opscode.com>)
+# Copyright:: Copyright (c) 2013 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 expressed or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License
+#
+
+require 'ohai/dsl/plugin'
+
+module Ohai
+  class NoAttributeError < Exception
+  end
+
+  class DependencyCycleError < Exception
+  end
+
+  class Runner
+    # safe_run: set to true if this runner will run plugins in
+    # safe-mode. default false.
+    def initialize(controller, safe_run = false)
+      @attributes = controller.attributes
+      @safe_run = safe_run
+    end
+
+    # runs this plugin and any un-run dependencies. if force is set to
+    # true, then this plugin and its dependencies will be run even if
+    # they have been run before.
+    def run_plugin(plugin, force = false)
+      visited = [plugin]
+      while !visited.empty?
+        p = visited.pop
+        unless force
+          next if p.has_run?
+        end
+
+        if visited.include?(p)
+          raise DependencyCycleError, "Dependency cycle detected. Please examine the following plugin files: #{cycle_sources(visited, p).join(", ")}"
+        end
+
+        dependency_providers = fetch_providers(p.dependencies)
+        dependency_providers.delete_if { |provider| (!force && provider.has_run?) || provider.eql?(p) }
+
+        if dependency_providers.empty?
+          @safe_run ? p.safe_run : p.run
+        else
+          visited << p << dependency_providers
+          visited.flatten!
+        end
+      end
+    end
+
+    # returns a list of plugins which provide the given attributes
+    def fetch_providers(attributes)
+      providers = []
+      attributes.each do |attribute|
+        attrs = @attributes
+        parts = attribute.split('/')
+        parts.each do |part|
+          next if part == Ohai::OS.collect_os
+          raise NoAttributeError, "Cannot find plugin providing attribute \'#{attribute}\'" unless attrs[part]
+          attrs = attrs[part]
+        end
+        providers << attrs[:providers]
+        providers.flatten!
+      end
+      providers.uniq!
+      providers
+    end
+
+    # given a list of plugins and the first plugin in the cycle,
+    # returns the list of plugin source files responsible for the
+    # cycle. does not include plugins that aren't a part of the cycle
+    def cycle_sources(plugins, cycle_start)
+      plugins.drop_while { |plugin| !plugin.eql?(cycle_start) }
+      sources = []
+      plugins.each { |plugin| sources << plugin.source }
+      sources
+    end
+
+  end
+end
diff --git a/lib/ohai/system.rb b/lib/ohai/system.rb
index bdc171d7..4a255eef 100644
--- a/lib/ohai/system.rb
+++ b/lib/ohai/system.rb
@@ -20,6 +20,7 @@ require 'ohai/loader'
 require 'ohai/log'
 require 'ohai/mash'
 require 'ohai/os'
+require 'ohai/runner'
 require 'ohai/dsl/plugin'
 require 'ohai/mixin/from_file'
 require 'ohai/mixin/command'
@@ -37,7 +38,7 @@ module Ohai
 
     def initialize
       @data = Mash.new
-      @attributes = Hash.new
+      @attributes = Mash.new
       @hints = Hash.new
       @v6_dependency_solver = Hash.new
       @plugin_path = ""
@@ -58,18 +59,29 @@ module Ohai
           file_regex = Regexp.new("#{File.expand_path(path)}#{File::SEPARATOR}(.+).rb$")
           md = file_regex.match(file)
           if md
-            plugin_path = md[0]
-            unless @v6_dependency_solver.has_key?(plugin_path)
-              plugin = loader.load_plugin(plugin_path)
-              @v6_dependency_solver[plugin_path] = plugin unless plugin.nil?
+            unless @v6_dependency_solver.has_key?(file)
+              plugin = loader.load_plugin(file)
+              @v6_dependency_solver[file] = plugin unless plugin.nil?
             else
-              Ohai::Log.debug("Already loaded plugin at #{plugin_path}")
+              Ohai::Log.debug("Already loaded plugin at #{file}")
             end
           end
         end
       end
     end
 
+    def run_plugins(safe = false, force = false)
+      runner = Ohai::Runner.new(self, safe)
+      plugins = collect_providers(@attributes)
+      begin
+        plugins.each { |plugin| runner.run_plugin(plugin, force) }
+      rescue DependencyCycleError, NoAttributeError => e
+        Ohai::Log.error("Encountered error while running plugins: #{e.inspect}")
+        raise
+      end
+      nil
+    end
+
     def all_plugins
       require_plugin('os')
 
@@ -97,19 +109,19 @@ module Ohai
     end
 
     def collect_providers(providers)
-      refreshments = []
+      plugins = []
       if providers.is_a?(Mash)
         providers.keys.each do |provider|
-          if provider.eql?("_providers")
-            refreshments << providers[provider]
+          if provider.eql?("providers")
+            plugins << providers[provider]
           else
-            refreshments << collect_providers(providers[provider])
+            plugins << collect_providers(providers[provider])
           end
         end
       else
-        refreshments << providers
+        plugins << providers
       end
-      refreshments.flatten.uniq
+      plugins.flatten.uniq
     end
 
     def refresh_plugins(path = '/')