extend the Chef provisioner base config object with an 'installer_download_path' property

plugins/provisioners/chef/config/base.rb

@@ -48,6 +48,14 @@ module VagrantPlugins
         # @return [String]
         attr_accessor :version
 
+        # The path where the Chef installer will be downloaded to. Only valid if 
+        # install is true or "force". It defaults to nil, which means that the
+        # omnibus installer will choose the destination and you have no control 
+        # over it. 
+        # 
+        # @return [String]
+        attr_accessor :installer_download_path
+
         def initialize
           super
 
@@ -57,6 +65,7 @@ module VagrantPlugins
           @log_level   = UNSET_VALUE
           @prerelease  = UNSET_VALUE
           @version     = UNSET_VALUE
+          @installer_download_path = UNSET_VALUE
         end
 
         def finalize!
@@ -66,6 +75,7 @@ module VagrantPlugins
           @log_level   = :info   if @log_level == UNSET_VALUE
           @prerelease  = false   if @prerelease == UNSET_VALUE
           @version     = :latest if @version == UNSET_VALUE
+          @installer_download_path = nil  if @installer_download_path == UNSET_VALUE
 
           # Make sure the install is a symbol if it's not a boolean
           if @install.respond_to?(:to_sym)

test/unit/plugins/provisioners/chef/config/base_test.rb

@@ -68,4 +68,11 @@ describe VagrantPlugins::Chef::Config::Base do
       expect(subject.version).to eq(:latest)
     end
   end
+
+  describe "#installer_download_path" do
+    it "defaults to nil" do
+      subject.finalize!
+      expect(subject.installer_download_path).to be(nil)
+    end
+  end
 end