Openstack Nova(九)----Instance 创建（Computer API & Conductor ），openstacknovaapi

Openstack Nova(九)----Instance 创建（Computer API & Conductor ），openstacknovaapi

在前一章中， 学习了所有的流水线处理。最后通过路由的设置，会把创建Instance的请求映射到servers.py的Controller的create方法。这中间会有不少的代码， 但都是一些常用的逻辑， 这里不进行讲述。

Controller/Create

这是一段比较长的代码， 但是做的事情还是比较简单。就是对各种参数的合法性检查。

@wsgi.response(202)
    @wsgi.serializers(xml=FullServerTemplate)
    @wsgi.deserializers(xml=CreateDeserializer)
    def create(self, req, body):
        """Creates a new server for a given user."""
        if not self.is_valid_body(body, 'server'):
            raise exc.HTTPUnprocessableEntity()
        #由前面的流水线生成的上下文环境
        context = req.environ['nova.context']
        #server的全部参数
        server_dict = body['server']
        #Instance的password
        password = self._get_server_admin_password(server_dict)
        #Instance的名称，这个不能为空
        if 'name' not in server_dict:
            msg = _("Server name is not defined")
            raise exc.HTTPBadRequest(explanation=msg)

        name = server_dict['name']
        #验证name的长度1-255
        self._validate_server_name(name)
        name = name.strip()
        #从当前参数中，取出image标识，有可能为空
        image_uuid = self._image_from_req_data(body)

        personality = server_dict.get('personality')
        config_drive = None
        if self.ext_mgr.is_loaded('os-config-drive'):
            config_drive = server_dict.get('config_drive')

        injected_files = []
        if personality:
            #需要注入的文件
            injected_files = self._get_injected_files(personality)

        #安全组配置
        sg_names = []
        if self.ext_mgr.is_loaded('os-security-groups'):
            security_groups = server_dict.get('security_groups')
            if security_groups is not None:
                sg_names = [sg['name'] for sg in security_groups
                            if sg.get('name')]
        if not sg_names:
            sg_names.append('default')

        sg_names = list(set(sg_names))
        #网络配置
        requested_networks = None
        if (self.ext_mgr.is_loaded('os-networks')
                or utils.is_neutron()):
            requested_networks = server_dict.get('networks')

        if requested_networks is not None:
            if not isinstance(requested_networks, list):
                expl = _('Bad networks format')
                raise exc.HTTPBadRequest(explanation=expl)
            requested_networks = self._get_requested_networks(
                requested_networks)
        #ipv4及有效性检查，只是针对IP地址本身，不会考虑其它单元的IP地址
        (access_ip_v4, ) = server_dict.get('accessIPv4'),
        if access_ip_v4 is not None:
            self._validate_access_ipv4(access_ip_v4)
        #ipv6及有效性检查，只是针对IP地址本身，不会考虑其它单元的IP地址
        (access_ip_v6, ) = server_dict.get('accessIPv6'),
        if access_ip_v6 is not None:
            self._validate_access_ipv6(access_ip_v6)

        try:
            #Instance的配置信息， 这个必须有
            flavor_id = self._flavor_id_from_req_data(body)
        except ValueError as error:
            msg = _("Invalid flavorRef provided.")
            raise exc.HTTPBadRequest(explanation=msg)

        # optional openstack extensions:
        key_name = None
        if self.ext_mgr.is_loaded('os-keypairs'):
            key_name = server_dict.get('key_name')

        user_data = None
        if self.ext_mgr.is_loaded('os-user-data'):
            user_data = server_dict.get('user_data')
        self._validate_user_data(user_data)
        #zone信息， 用来对Instance进行分区，分区基于HOST
        availability_zone = None
        if self.ext_mgr.is_loaded('os-availability-zone'):
            availability_zone = server_dict.get('availability_zone')
        #硬盘信息， 可以做为启动盘
        block_device_mapping = None
        block_device_mapping_v2 = None
        legacy_bdm = True
        if self.ext_mgr.is_loaded('os-volumes'):
            block_device_mapping = server_dict.get('block_device_mapping', [])
            for bdm in block_device_mapping:
                try:
                    block_device.validate_device_name(bdm.get("device_na