Generate ansible_hosts file if one is not provided

plugins/provisioners/ansible/provisioner.rb

@@ -3,10 +3,10 @@ module VagrantPlugins
     class Provisioner < Vagrant.plugin("2", :provisioner)
       def provision
         ssh = @machine.ssh_info
-
+        inventory_file_path = self.setup_inventory_file
         options = %W[--private-key=#{ssh[:private_key_path]} --user=#{ssh[:username]}]
         options << "--extra-vars=" + config.extra_vars.map{|k,v| "#{k}=#{v}"}.join(' ') if config.extra_vars
-        options << "--inventory-file=#{config.inventory_file}" if config.inventory_file
+        options << "--inventory-file=#{inventory_file_path}"
         options << "--ask-sudo-pass" if config.ask_sudo_pass
 
         if config.limit
@@ -40,6 +40,19 @@ module VagrantPlugins
           raise Vagrant::Errors::AnsiblePlaybookAppNotFound
         end
       end
+      
+      def setup_inventory_file()
+        if config.inventory_file
+          return config.inventory_file
+        end
+        ssh = @machine.ssh_info
+        generated_inventory_file = "vagrant_ansible_inventory_#{machine.name}"
+        File.open(generated_inventory_file, 'w') do |file|
+          file.write("# Generated by Vagrant\n\n")
+          file.write("#{machine.name} ansible_ssh_host=#{ssh[:host]} ansible_ssh_port=#{ssh[:port]}\n")
+        end
+        return generated_inventory_file
+      end
     end
   end
 end