[COOK-2885] - Add attribute, exclude node

* Set an attribute (caching_server) to true if the node should be a
  caching server. This is done in the cacher-ng recipe.
* Search for the server based on the above attribute.
* Exclude the node itself from search, else apt may fail to install
  packages.
* Update metadata with attributes.

Author: jtimberman

README.md

@@ -53,12 +53,14 @@ includes the `cacher-client` recipe, so it helps seed itself.
 
 cacher-client
 -------------
+
 Configures the node to use the `apt-cacher-ng` server as a client. If you
 want to restrict your node to using the `apt-cacher-ng` server in your
 Environment, set `['apt']['cacher-client']['restrict_environment']` to `true`.
+
 To use a cacher server (or standard proxy server) not available via search
 set the atttribute `['apt']['cacher-ipaddress']` and for a custom port
-set `['apt']['cacher_port']`
+set `['apt']['cacher_port']`.
 
 Resources/Providers
 ===================

attributes/default.rb

@@ -1,3 +1,4 @@
 default['apt']['cacher-client']['restrict_environment'] = false
 default['apt']['cacher_port'] = 3142
 default['apt']['key_proxy'] = ''
+default['apt']['caching_server'] = false

metadata.rb

@@ -12,3 +12,19 @@
 %w{ ubuntu debian }.each do |os|
   supports os
 end
+
+attribute "apt/cacher-client/restrict_environment",
+  :description => "Whether to restrict the search for the caching server to the same environment as this node",
+  :default => false
+
+attribute "apt/cacher_port",
+  :description => "Default listen port for the caching server",
+  :default => "3142"
+
+attribute "apt/key_proxy",
+  :description => "Passed as the proxy passed to GPG for the apt_repository resource"
+  :default => ""
+
+attribute "apt/caching_server",
+  :description => "Set this to true if the node is a caching server"
+  :default => false

recipes/cacher-client.rb

@@ -33,7 +33,7 @@
 end
 
 unless Chef::Config[:solo]
-  query = 'recipes:apt\:\:cacher-ng'
+  query = "apt_caching_server:true NOT name:#{node.name}"
   query += " AND chef_environment:#{node.chef_environment}" if node['apt']['cacher-client']['restrict_environment']
   Chef::Log.debug("apt::cacher-client searching for '#{query}'")
   servers += search(:node, query)

recipes/cacher-ng.rb

@@ -17,6 +17,8 @@
 # limitations under the License.
 #
 
+node.set['apt']['caching_server'] = true
+
 package "apt-cacher-ng" do
   action :install
 end