Nova Instance Create

26 January 2014

##Nova创建实例代码分析

####版本：Havana ####说明： –> 为调用下一流程 Appendix 为变量的内容

###主要API解析 run_instances(self, context, kwargs):

kwargs{'max_count' : int
       'min_count' : int
       'kernel_id' : str
       'ramdisk_id': str
       'key_name'  : str
       'user_data' : str
       'security_group' : str
       'placement'      : {}
       'block_device_mapping' :{}
        }

1. 初始化参数:
_resv_id_from_token(context, client_token)
_format_run_instances(context, resv_id)
_get_image(context, kwargs['ramdisk_id'])
parse_block_device_mapping(bdm)
__get_image_state(image)
flavor_obj.Flavor.get_by_name(context,kwargs.get('instance_type',None))

2. 传递参数，调用关键函数 
from nova.compute import api as compute_api
compute_api.create(context,
        instance_type=obj_base.obj_to_primitive(flavor),
        image_href=image_uuid,
        max_count=int(kwargs.get('max_count', min_count)),
        min_count=min_count,
        kernel_id=kwargs.get('kernel_id'),
        ramdisk_id=kwargs.get('ramdisk_id'),
        key_name=kwargs.get('key_name'),
        user_data=kwargs.get('user_data'),
        security_group=kwargs.get('security_group'),
        availability_zone=kwargs.get('placement', {}).get('availability_zone'),
        block_device_mapping=kwargs.get('block_device_mapping', {}))

###1._get_image(self, context, ec2_id):

Function 
    根据ec2_id获取指定参数的实例的元数据

Workflow:
    internal_id = ec2utils.ec2_id_to_id(ec2_id)
    image_service.show(context, internal_id) :关键函数
    image_type = ec2_id.split('-')[0]

return image

####1.1 image_service.show(context, internal_id) 1）image_uuid :根据给定的image_id值，查询数据库，找到匹配的表信息，获取它的S3Image.uuid并返回，赋值给image_uuid 2）直接得到service 或尝试一定次数调用glance客户端的get方法，获取image_id指定的镜像元数据（此时为JSON格式）,把glance下载的镜像数据转换为python可处理的字典格式； 3）根据元数据中的glance id值查找到匹配的S3格式镜像数据信息，进一步获取的S3数据库id值赋值给image_copy[‘id’]、image_copy[‘properties’][‘kernel_id’]和image_copy[‘properties’][‘ramdisk_id’]；更新image当中的相关属性，返回更新后的image数据；

根据配置参数确定最大链接访问glance客户端的次数，在不超过最大次数的情况下，尝试确定正确的客户端版本，建立glance客户端类的对象，通过glance客户端中images.py中的get方法，获取指定的镜像元数据；

###2. _parse_block_device_mapping()

解析块设备映射bdm；
这个方法主要完成的就是读取数据库，获取相应数据更新上述实例数据中的'snapshot_id'和'volume_id'值；
   ( {'device_name': '/dev/fake0',
      'ebs': {'snapshot_id': 'snap-12345678',
               'volume_size': 1}},
      {'device_name': '/dev/fake0',
       'snapshot_id': '00000000-1111-2222-3333-444444444444',
       'volume_size': 1,
       'delete_on_termination': True})

###3. compute_api.create() 1. 根据给定的参数是否满足policy来决定是否有create的资格 2. neutron启动多个实例时，处理端口的分配问题。 3. 准备实例，并且发送实例的信息和要运行实例的请求消息到远程调度器scheduler; 实现实例的简历和运行，由调度器决定，这部分代码实际上只是实现请求消息的发送；
返回一个元组（实例或者是reservation_id的元组），元组里面的实例可以是“None”或者是实例字典的一个列表，这要取决于是否等待scheduler返回的信息；

####3.1 _create_instance() 1. 初始化传入参数 2. 验证传入参数的有效性,返回要建立实例的各类信息
3. Verify all the input parameters regardless of the provisioning strategy being performed and schedule the instance(s) for creation.

1.  (base_options,max_net_count) = validate_and_build_base_options()
2. _check_and_transform_bdm(self, base_options, image_meta, min_count,
                             max_count, block_device_mapping, legacy_bdm):
3. _provision_instances(self, context, instance_type, min_count,
        max_count, base_options, boot_meta, security_groups,block_device_mapping):
4. _build_filter_properties(self, context, scheduler_hints, forced_host,forced_node, instance_type):
5. _record_action_start(self, context, instance, action):
	获取每个实例启动的一些信息，并在数据库中建立新的条目，把这些信息写入数据库。
6. compute_task_api.build_instances()
    ComputeTaskAPI(*args, **kwargs)

return (instances, reservation_id)

#####3.1.1 compute_task_api.build_instances() 实际调用: if nova.compute.api 的 API中指定了compute_task_api else –> self._compute_task_api = nova.conductor.ComputeTaskAPI() if oslo.config.cfg.CONF.conductor.use_local //nova.conductor.api –> nova.conductor.api.LocalComputeTaskAPI().build_instances(ARGS1) –> nova.utils.spawn_n( utils.ExceptionHelper(mananger.ComputeTaskManager()).build_instances(), ARGS) –> eventlet.spawn_n(utils.ExceptionHelper(mananger.ComputeTaskManager().build_instances(), ARGS)) –> nova.utils.ExceptionHelper(mananger.ComputeTaskManager().build_instances(), ARGS) –> nova.conductor.mananger.ComputeTaskManager().build_instances(ARGS) –> nova.scheduler.rpcapi.run_instances(ARGS) –> cctxt = nova.rpcclient.RpcProxy().get_client() nova.rpcclient.prepare().cast(cctxt, ‘run_instance’, ARGS)

             --> 
                 nova.openstack.common.rpc.proxy.cast_to_server()  OR
                 nova.openstack.common.rpc.proxy.fanout_cast_to_server() OR
                 nova.openstack.common.rpc.proxy.fanout_cast() : Broadcast a remote method invocation with no return
             -->
                 importutils.import_module(oslo.config.cfg.CONF.rpc_backend).fanout_cast_to_server()
                 importutils.import_module(oslo.config.cfg.CONF.rpc_backend).cast_to_server()
                 importutils.import_module(oslo.config.cfg.CONF.rpc_backend).fanout_cast()
             --> 
                 nova.openstack.common.rpc.impl_kombu.fanout_cast_to_server()
                 nova.openstack.common.rpc.impl_kombu.cast_to_server()
                 nova.openstack.common.rpc.impl_kombu.fanout_cast()
             -->
                 nova.openstack.common.rpc.amqp.cast_to_server(conf, context,
                 server_params, topic, msg,
                 rpc_amqp.get_connection_pool(conf, Connection))

                 nova.openstack.common.rpc.amqp.fanout_cast(conf, context,
                 server_params, topic, msg,
                 rpc_amqp.get_connection_pool(conf, Connection))

                 nova.openstack.common.rpc.amqp.fanout_cast_to_server(conf,
                 context, server_params, topic, msg,
                 rpc_amqp.get_connection_pool(conf, Connection))

             --> 
                 """Sends a message on a fanout exchange without waiting for a response."""
                 nova.openstack.common.rpc.amqp.fanout_cast((conf,
                 context, server_params, topic, msg,
                 rpc_amqp(conf, kombu.Connection.BrokerConnection()))

                 """Sends a message on a fanout exchange to a specific server."""
                 nova.openstack.common.rpc.amqp.fanout_cast_to_server((conf,
                 context, server_params, topic, msg,
                 rpc_amqp(conf, kombu.Connection.BrokerConnection()))

                """Sends a message on a topic to a specific server."""
                 nova.openstack.common.rpc.amqp.cast_to_server((conf,
                 context, server_params, topic, msg,
                 rpc_amqp(conf, kombu.Connection.BrokerConnection()))

             -->
             nova.openstack.common.rpc.amqp.ConnectionContext.fanout_send()
             nova.openstack.common.rpc.amqp.ConnectionContext.topic_send()

             -->
             nova.openstack.common.rpc.common.Connection.fanout
             nova.openstack.common.rpc.amqp.get_connection_pool(conf, kombu.Connection.BrokerConnection())

             --> kombu.Connection.BrokerConnection.pool

     else 
         --> nova.conductor.api.ComputeTaskAPI().build_instances(ARGS)
         --> nova.rpcapi.ComputeTaskAPI().build_instances(ARGS)

##整个创建实例的主线代码调用

nova.api.ec2.cloud.run_instances(context, kwargs)
--> 
    nova.compute.api.create(ARGS)
--> 
    nova.compute.api._create_instance(ARGS)

    -->     
        nova.compute.api.compute_task_api(self)
    -->
        nova.conductor.ComputeTaskAPI()
    --> 
        nova.conductor.api.ComputeTaskAPI(args, kwargs)     
        OR
        nova.conductor.api.LocalComputeTaskAPI(args, kwargs)
-->
    nova.conductor.api.ComputeTaskAPI.build_instances(ARGS1)
    OR
    nova.conductor.api.LocalComputeTaskAPI.build_instances(ARGS1)


1. nova.conductor.api.ComputeTaskAPI.build_instances(ARGS1)
 -->
    nova.conductor.rpcapi.ComputeTaskAPI.build_instances(ARGS1)
    -->
        cctxt = nova.rpcclient.RpcProxy().get_client(namespace='compute_task').prepare()
        cctxt = nova.rpcclient.RPCClient('compute_task',None).prepare(version=1.5)
 -->
    nova.rpcclient.RPCClient.prepare.cast(context, 'build_instance', ARGS.1-context)
 -->
    nova.openstack.common.rpc.proxy.fanout_cast_to_server(context,
                                        'build_instances', msg, kwargs)
OR
    nova.openstack.common.rpc.proxy.cast_to_server(context, msg, 
                                        'build_instances', kwargs)
OR
    nova.openstack.common.rpc.proxy.fanout_cast(context, msg, 
                                        'build_instances', kwargs)

 -->
     importutils.import_module(oslo.config.cfg.CONF.rpc_backend).fanout_cast_to_server()
OR
     importutils.import_module(oslo.config.cfg.CONF.rpc_backend).cast_to_server()
OR
     importutils.import_module(oslo.config.cfg.CONF.rpc_backend).fanout_cast()

 -->
    """Sends a message on a topic to a specific server."""
     nova.openstack.common.rpc.amqp.cast_to_server(CONF, context,'build_instances', topic, msg,
                                                    rpc_amqp.get_connection_pool(conf, Connection))
OR
     """Sends a message on a fanout exchange to a specific server."""
     nova.openstack.common.rpc.amqp.fanout_cast_to_server(conf, context, 'build_instances', topic, msg,
                                                    rpc_amqp.get_connection_pool(conf, Connection))
OR
     """Sends a message on a fanout exchange without waiting for a response."""
     nova.openstack.common.rpc.amqp.fanout_cast(conf, context,topic, msg,
                                                    rpc_amqp.get_connection_pool(conf, Connection))

 -->
    POOL = rpc_amqp.get_connection_pool(conf, Connection)
    nova.openstack.common.rpc.amqp.ConnectionContext(CONF,POOL).fanout_send('build_instances', msg)
OR
    nova.openstack.common.rpc.amqp.ConnectionContext(CONF,POOL).topic_send('build_instances', msg)

 --> 
    Connection = nova.openstack.common.rpc.amqp.get_connection_pool(conf,Connection).get()
    Connection.fanout_cast('build_instances')
    Connection.topic_send('build_instances')

    Connection =
    nova.openstack.common.rpc.amqp.get_connection_pool(conf,Connection).connection_cls(CONF,
            'build_instances')
    Connection.topic_send('build_instances')
    Connection.fanout_cast('build_instances')

 -->
    nova.openstack.common.rpc.impl_kombu.Connection.fanout_send('build_instances', msg)
    nova.openstack.common.rpc.impl_kombu.Connection.topic_send('build_instances', msg)

 -->
    nova.openstack.common.rpc.impl_kombu.Connection.publisher_send(TopicPublisher,'build_instances', msg)
    nova.openstack.common.rpc.impl_kombu.Connection.topic_send(FanoutPublisher,'build_instances', msg)

2. nova.conductor.api.LocalComputeTaskAPI().build_instances(ARGS1)
 --> nova.utils.spawn_n(
                    utils.ExceptionHelper(mananger.ComputeTaskManager()).build_instances(), 
                    ARGS1)
 -->
     eventlet.spawn_n(utils.ExceptionHelper(mananger.ComputeTaskManager().build_instances(), ARGS))
 -->
     nova.utils.ExceptionHelper(mananger.ComputeTaskManager().build_instances(), ARGS)
 --> nova.conductor.mananger.ComputeTaskManager().build_instances(ARGS)
 --> nova.scheduler.rpcapi.run_instances(ARGS)
     -->
        cctxt = nova.rpcclient.RpcProxy().get_client()
        cctxt = nova.rpcclient.RPCClient()
 -->
    nova.rpcclient.RPCClient.prepare().cast(context,'run_instance', ARGS2)

 --> 
     nova.openstack.common.rpc.proxy.cast_to_server(context, 'run_instances', 
                                                            msg,{})  
OR
     nova.openstack.common.rpc.proxy.fanout_cast_to_server(context,'run_instances',
                                                            msg,{}) 
OR
     nova.openstack.common.rpc.proxy.fanout_cast(context, msg, {}) 
 -->
     importutils.import_module(oslo.config.cfg.CONF.rpc_backend).fanout_cast_to_server(CONF,context,'build_instances',topic,msg)
OR
     importutils.import_module(oslo.config.cfg.CONF.rpc_backend).cast_to_server(CONF,context,'build_instances', topic,msg)
OR
     importutils.import_module(oslo.config.cfg.CONF.rpc_backend).fanout_cast(CONF,context,topic,msg)
 --> 
     nova.openstack.common.rpc.impl_kombu.fanout_cast_to_server(CONF,context,'build_instances',topic,msg)
OR
     nova.openstack.common.rpc.impl_kombu.cast_to_server(CONF,context,'build_instances',topic,msg)
OR
     nova.openstack.common.rpc.impl_kombu.fanout_cast(CONF,context,topic,msg)
 -->
    """Sends a message on a topic to a specific server."""
     nova.openstack.common.rpc.amqp.cast_to_server(CONF, context,'build_instances', topic, msg,
                                                    rpc_amqp.get_connection_pool(conf, Connection))
OR
     """Sends a message on a fanout exchange to a specific server."""
     nova.openstack.common.rpc.amqp.fanout_cast_to_server(conf, context, 'build_instances', topic, msg,
                                                    rpc_amqp.get_connection_pool(conf, Connection))
OR
     """Sends a message on a fanout exchange without waiting for a response."""
     nova.openstack.common.rpc.amqp.fanout_cast(conf, context,topic, msg,
                                                    rpc_amqp.get_connection_pool(conf, Connection))


 --> 
     """Sends a message on a fanout exchange without waiting for a response."""
     nova.openstack.common.rpc.amqp.fanout_cast((conf,
     context, server_params, topic, msg,
     rpc_amqp(conf, kombu.Connection.BrokerConnection()))

     """Sends a message on a fanout exchange to a specific server."""
     nova.openstack.common.rpc.amqp.fanout_cast_to_server((conf,
     context, server_params, topic, msg,
     rpc_amqp(conf, kombu.Connection.BrokerConnection()))

    """Sends a message on a topic to a specific server."""
     nova.openstack.common.rpc.amqp.cast_to_server((conf,
     context, server_params, topic, msg,
     rpc_amqp(conf, kombu.Connection.BrokerConnection()))

 -->
    nova.openstack.common.rpc.amqp.ConnectionContext.fanout_send()
    nova.openstack.common.rpc.amqp.ConnectionContext.topic_send()

 -->
 nova.openstack.common.rpc.common.Connection.fanout
 nova.openstack.common.rpc.amqp.get_connection_pool(conf, kombu.Connection.BrokerConnection())

 --> kombu.Connection.BrokerConnection.pool

##Appendix ###ARGS: context = <nova.context.RequestContext object at 0x447d050>
{ user_id = afc380206e2549ad930396d9050d20cf
project_id = 0e492e86f22e4d19bd523f1e7ca64566
roles = [u’admin’, u’KeystoneAdmin’, u’KeystoneServiceAdmin’]
read_deleted = no
remote_address = 172.21.6.145
timestamp = 2013-06-23 16:36:37.399405
request_id = req-f0255b14-833d-4fff-b973-23c35f70ddda
auth_token = 7e7bb3cf84ab43269010bb55410064b3
service_catalog = [{u’endpoints’: [ {u’adminURL’: u’http://172.21.5.161:8776/v1/0e492e86f22e4d19bd523f1e7ca64566’, u’region’: u’RegionOne’, u’id’: u’753a1ad55e91469794e2eb7ac4c3df92’, u’internalURL’: u’http://172.21.5.161:8776/v1/0e492e86f22e4d19bd523f1e7ca64566’, u’publicURL’: u’http://172.21.6.145:8776/v1/0e492e86f22e4d19bd523f1e7ca64566’}], u’endpoints_links’: [], u’type’: u’volume’, u’name’: u’cinder’}]
instance_lock_checked = False
quota_class = None
user_name = admin
project_name = admin
is_admin = True
} instance_type = { ‘memory_mb’: 2048L, ‘root_gb’: 20L, ‘deleted_at’: None, ‘name’: u’m1.small’, ‘deleted’: 0L, ‘created_at’: None, ‘ephemeral_gb’: 0L, ‘updated_at’: None, ‘disabled’: False, ‘vcpus’: 1L, ‘extra_specs’: {}, ‘swap’: 0L, ‘rxtx_factor’: 1.0, ‘is_public’: True, ‘flavorid’: u’2’, ‘vcpu_weight’: None, ‘id’: 5L}
image_href = 20612b24-c980-4900-b270-8e6b66e5f72f
kernel_id = None
ramdisk_id = None
min_count = 1
max_count = 1
display_name = test3
display_description = test3
key_name = oskey
key_data = None
security_group = [‘default’]
availability_zone = None
user_data = None
metadata = {}
injected_files = []
admin_password = Piu4aSSNmSNk
block_device_mapping = []
access_ip_v4 = None
access_ip_v6 = None
requested_networks = None
config_drive = None
auto_disk_config = None
scheduler_hints = {}
legacy_bdm = True ###ARGS.1 (context, instances=instances, image=boot_meta, filter_properties=filter_properties, admin_password=admin_password, injected_files=injected_files, requested_networks=requested_networks, security_groups=security_groups, block_device_mapping=block_device_mapping, legacy_bdm=False)

###ARGS.2 (context, instances = [nova.compute.api._apply_instance_name_template(), )

###ARGS2 msg_kwargs = {‘request_spec’: request_spec, ‘admin_password’: admin_password, ‘injected_files’: injected_files, ‘requested_networks’: requested_networks, ‘is_first_time’: is_first_time, ‘filter_properties’: filter_properties}

###msg ( ‘method’ : nova.rpcclient.RPCClient.prepare() ‘namespce’: ‘run_instances’ OR ‘build_instances’ ‘args’ : ARGS1 ‘version’ : str ‘oslo.version’ : 2.0 ‘oslo.message’ : msg of json )

OpenStack 4

OpenStack 3

Nova Instance Create nova instance create