Merge pull request #35 from jayofdoom/jay/OptionalFindExtrasPackage

Use kernel release for package name on saucy and newer

recipes/aufs.rb

@@ -1,16 +1,19 @@
 case node['platform']
 when 'ubuntu'
-  #
-  # The below code copied from: https://github.com/thoward/docker-cookbook/blob/master/recipes/default.rb
-  # It's not pretty, but gets the job done!
-  #
-  # If aufs isn't available, do our best to install the correct
-  # linux-image-extra package. This is somewhat messy because the
-  # naming of these packages is very inconsistent across kernel
-  # versions
-  extra_package = Mixlib::ShellOut.new("apt-cache search linux-image-extra-`uname -r | grep --only-matching -e [0-9]\.[0-9]\.[0-9]-[0-9]*` | cut -d ' ' -f 1").run_command.stdout.strip
+  # If aufs isn't available, do our best to install the correct linux-image-extra package.
+  # Use kernel release for saucy and newer, otherwise use older, more compatible regexp match
+  if Gem::Version.new(node['platform_version']) < Gem::Version('13.10')
+    # Original method copied from https://github.com/thoward/docker-cookbook/blob/master/recipes/default.rb
+    package_name = 'linux-image-extra-' + Mixlib::ShellOut.new("uname -r | grep --only-matching -e [0-9]\.[0-9]\.[0-9]-[0-9]*").run_command.stdout.strip
+  else
+    # In modern ubuntu versions, kernel release matches the kernel package name
+    package_name = 'linux-image-extra-' + node['kernel']['release']
+  end
+
+  extra_package = Mixlib::ShellOut.new('apt-cache search ' + package_name).run_command.stdout.split(' ').first
+  # Wait to strip until after checking for empty, to protect against nil errors
   unless extra_package.empty?
-    package extra_package do
+    package extra_package.strip do
       not_if 'modprobe -l | grep aufs'
     end
   end