[openstack|compute] support block_device_mapping

Servers can be booted with block_device_mapping instead of image_id.

lib/fog/openstack/models/compute/server.rb

@@ -41,6 +41,7 @@ module Fog
 
         attr_reader :password
         attr_writer :image_ref, :flavor_ref, :nics, :os_scheduler_hints
+        attr_accessor :block_device_mapping
 
 
         def initialize(attributes={})
@@ -52,6 +53,7 @@ module Fog
           self.max_count = attributes.delete(:max_count)
           self.nics = attributes.delete(:nics)
           self.os_scheduler_hints = attributes.delete(:os_scheduler_hints)
+          self.block_device_mapping = attributes.delete(:block_device_mapping)
 
           super
         end
@@ -267,10 +269,10 @@ module Fog
           true
         end
 
-        # TODO: Implement /os-volumes-boot support with 'block_device_mapping'
         def save
           raise Fog::Errors::Error.new('Resaving an existing object may create a duplicate') if persisted?
-          requires :flavor_ref, :image_ref, :name
+          requires :flavor_ref, :name
+          requires_one :image_ref, :block_device_mapping
           options = {
             'personality' => personality,
             'accessIPv4' => accessIPv4,
@@ -283,6 +285,7 @@ module Fog
             'max_count'   => @max_count,
             'nics' => @nics,
             'os:scheduler_hints' => @os_scheduler_hints,
+            'block_device_mapping' => @block_device_mapping
           }
           options['metadata'] = metadata.to_hash unless @metadata.nil?
           options = options.reject {|key, value| value.nil?}

lib/fog/openstack/requests/compute/create_server.rb

@@ -56,11 +56,29 @@ module Fog
             data['os:scheduler_hints'] = options['os:scheduler_hints']
           end
 
+          if options['block_device_mapping']
+            data['server']['block_device_mapping'] =
+            [options['block_device_mapping']].flatten.map do |mapping|
+              {
+                'volume_size' => mapping[:volume_size],
+                'volume_id' => mapping[:volume_id],
+                'delete_on_termination' => mapping[:delete_on_termination],
+                'device_name' => mapping[:device_name]
+              }
+            end
+          end
+
+          path = if data['server']['block_device_mapping']
+                   'os-volumes_boot.json'
+                 else
+                   'servers.json'
+                 end
+
           request(
             :body     => Fog::JSON.encode(data),
             :expects  => [200, 202],
             :method   => 'POST',
-            :path     => 'servers.json'
+            :path     => path
           )
         end