[转]OpenStack extension api

原作者：张华
原文链接

openstack的扩展API有两类：
1) resource extension, 可参见：$nova/nova/api/openstack/compute/contrib/server_password.py, 需实现get_resource方法，如：

def get_resources(self):  
      member_actions = {'action': 'POST'}  
      collection_actions = {'add': 'POST'}  
      res = extensions.ResourceExtension(  
          'os-networks',  
          NetworkController(),  
          member_actions=member_actions,  
          collection_actions=collection_actions)  
      return [res]  
　　　 会产生如下格式的REST URL:
    GET    /os-networks           
    POST   /os-networks      
    POST   /os-networks/add      
    PUT    /os-networks/id     
    DELETE /os-networks/id     
    GET    /os-networks/id    
    POST   /os-networks/id/action

2) controller extension, 可参见：$nova/nova/api/openstack/compute/contrib/server_password.py, 需实现get_controller_extensions方法，如：

def get_controller_extensions(self):  
       　controller = Controller(self.ext_mgr)  
       　extension = extensions.ControllerExtension(self, 'servers', controller)  
       　return [extension]

　　但是，如果不是新建，而是想扩展已存在的resource extension和extroller extension呢，如下的例子：
　　１）加@wsgi.extends(action=’resize’)修饰符即可
　　２）记得加yield，让它成为一个生成器，这样就会先执行我们自己扩展的extension api，然后再去执行原有的api，相当于继承吧。

class Server_resource(extensions.ExtensionDescriptor):  
    """Start/Stop instance compute API support."""  

    name = "ServerResource"  
    alias = "os-server-resource"  
    namespace = "http://docs.openstack.org/compute/ext/server-resource/api/v1.1"  
    updated = "2013-01-13T00:00:00+00:00"  

    def get_controller_extensions(self):  
        controller = ServerController()  
        extension = extensions.ControllerExtension(self, 'servers', controller)  
        return [extension]  

class ServerController(wsgi.Controller):  

    def __init__(self):  
        print 'init'  

    @wsgi.extends  
    def create(self, req, body):  
        print 'update'  
　   　 yield  

    @wsgi.extends(action='resize')  
    def _action_resize(self, req, id, body):  
        print 'resize'  
        yield

因为上面是一个生成器，可以这样调用：
[python]self.controller.create(req, body).next()[/python]
或者用for循环调用。另外在单元测试时使用assertRaises时调用它时传给Mock的应该是一个函数地址，所以下面的调用在next后面不要加括号哦。
[python]self.assertRaises(exc.HTTPBadRequest, self.controller.create(req, body).next)[/python]

测试：

TOKEN=`curl -s -d "{\"auth\":{\"passwordCredentials\":{\"username\": \"$OS_USERNAME\", \"password\":\"$OS_PASSWORD\"}, \"tenantName\":\"$OS_TENANT_NAME\"}}" -H "Content-type:application/json" $OS_AUTH_URL/tokens | python -c"import sys; import json; tok = json.loads(sys.stdin.read()); print tok['access']['token']['id'];"`

curl -i -X POST -H "Content-Type: application/json" -H "X-Auth-Token:$TOKEN" -d '{"server": {"flavorRef": "http://openstack.example.com/openstack/flavors/1","imageRef": "http://openstack.example.com/openstack/images/e0ba6d0a-c705-4dbd-bd3b-b35bbbb8f8a5","name":"i1","ram":"1024","vcpus":"1","disk":"10"}}' http://192.168.0.1:8774/v2/5685706e11ff4e9fb4ffdfac7ed2fb6e/servers

curl -i -X POST -H "Content-Type: application/json" -H "X-Auth-Token:$TOKEN" -d '{"resize" : {"flavorRef" : "2","ram":"1024","vcpus":"1","disk":"10"}}' http://192.168.0.1:8774/v2/5685706e11ff4e9fb4ffdfac7ed2fb6e/servers/ec95e413-f033-4f02-a9c4-b16fe7d398cd/action