Add ability for SIGUSR1 to wakeup the daemon and start a chef run.

Author: ctennis

chef/lib/chef/application.rb

@@ -24,6 +24,9 @@
 class Chef::Application
   include Mixlib::CLI
 
+  class Wakeup < Exception
+  end
+
   def initialize
     super
 
@@ -46,6 +49,17 @@ def initialize
       end
     end
 
+    unless RUBY_PLATFORM =~ /mswin|mingw32|windows/
+      trap("USR1") do
+        Chef::Log.info("SIGUSR1 received, starting run")
+        raise Chef::Application::Wakeup
+      end
+    end
+
+    at_exit do
+      # tear down the logger
+    end
+
     # Always switch to a readable directory. Keeps subsequent Dir.chdir() {}
     # from failing due to permissions when launched as a less privileged user.
   end

chef/lib/chef/application/client.rb

@@ -223,6 +223,9 @@ def run_application
         else
           Chef::Application.exit! "Exiting", 0
         end
+      rescue Chef::Application::Wakeup => e
+        Chef::Log.debug("Received Wakeup signal.  Starting run.")
+        next
       rescue SystemExit => e
         raise
       rescue Exception => e