Nova 启动虚拟机流程解析
目录
文章目录
前言
Nova 启动虚拟机的东西太多，持续更新…node
从请求提及
不管是经过 Dashboard 仍是 CLI 启动一个虚拟机，发送的是 POST /servers请求，改与该请求的 Body 详情，能够浏览官方文档 Create server。python
nova-api service 阶段
Nova API Service 本质是一个 WSGI Application，采用了 Paste + PasteDeploy + Routes + WebOb 框架，简称 PPRW。关于架构的实现不属于本文范畴，因此直接看接收到 POST /servers 请求以后的处理函数（View Method）create。web
NOTE：首先须要说明的是，下文中全部的代码解析均直接经过注释的方式呈现完成。数据库
# File: /opt/stack/nova/nova/api/openstack/compute/servers.py @wsgi.response(202) @wsgi.expected_errors((400, 403, 409)) @validation.schema(schema_servers.base_create_v20, '2.0', '2.0') @validation.schema(schema_servers.base_create, '2.1', '2.18') @validation.schema(schema_servers.base_create_v219, '2.19', '2.31') @validation.schema(schema_servers.base_create_v232, '2.32', '2.32') @validation.schema(schema_servers.base_create_v233, '2.33', '2.36') @validation.schema(schema_servers.base_create_v237, '2.37', '2.41') @validation.schema(schema_servers.base_create_v242, '2.42', '2.51') @validation.schema(schema_servers.base_create_v252, '2.52', '2.56') @validation.schema(schema_servers.base_create_v257, '2.57', '2.62') @validation.schema(schema_servers.base_create_v263, '2.63', '2.66') @validation.schema(schema_servers.base_create_v267, '2.67') def create(self, req, body): """Creates a new server for a given user.""" context = req.environ['nova.context'] server_dict = body['server'] # 用户设置的虚拟机密码 password = self._get_server_admin_password(server_dict) name = common.normalize_name(server_dict['name']) description = name if api_version_request.is_supported(req, min_version='2.19'): description = server_dict.get('description') # Arguments to be passed to instance create function create_kwargs = {} # 须要注入到虚拟机的 user_data 数据（Configuration information or scripts to use upon launch.） create_kwargs['user_data'] = server_dict.get('user_data') # NOTE(alex_xu): The v2.1 API compat mode, we strip the spaces for # keypair create. But we didn't strip spaces at here for # backward-compatible some users already created keypair and name with # leading/trailing spaces by legacy v2 API. # keypair 名称 create_kwargs['key_name'] = server_dict.get('key_name') # 是否启用 config_drive（布尔值） create_kwargs['config_drive'] = server_dict.get('config_drive') # 虚拟机安全组 security_groups = server_dict.get('security_groups') if security_groups is not None: create_kwargs['security_groups'] = [ sg['name'] for sg in security_groups if sg.get('name')] create_kwargs['security_groups'] = list( set(create_kwargs['security_groups'])) # 虚拟机调度提示信息，是一种高级的调度因子 scheduler_hints = {} if 'os:scheduler_hints' in body: scheduler_hints = body['os:scheduler_hints'] elif 'OS-SCH-HNT:scheduler_hints' in body: scheduler_hints = body['OS-SCH-HNT:scheduler_hints'] create_kwargs['scheduler_hints'] = scheduler_hints # min_count and max_count are optional. If they exist, they may come # in as strings. Verify that they are valid integers and > 0. # Also, we want to default 'min_count' to 1, and default # 'max_count' to be 'min_count'. min_count = int(server_dict.get('min_count', 1)) max_count = int(server_dict.get('max_count', min_count)) return_id = server_dict.get('return_reservation_id', False) if min_count > max_count: msg = _('min_count must be <= max_count') raise exc.HTTPBadRequest(explanation=msg) create_kwargs['min_count'] = min_count create_kwargs['max_count'] = max_count create_kwargs['return_reservation_id'] = return_id # 指定可用域 availability_zone = server_dict.pop("availability_zone", None) # 虚拟机 tags 信息 if api_version_request.is_supported(req, min_version='2.52'): create_kwargs['tags'] = server_dict.get('tags') helpers.translate_attributes(helpers.CREATE, server_dict, create_kwargs) target = { 'project_id': context.project_id, 'user_id': context.user_id, 'availability_zone': availability_zone} # 验证 target 是否支持 create 操做 context.can(server_policies.SERVERS % 'create', target) # Skip policy check for 'create:trusted_certs' if no trusted # certificate IDs were provided. # 镜像证书 trusted_certs = server_dict.get('trusted_image_certificates', None) if trusted_certs: create_kwargs['trusted_certs'] = trusted_certs context.can(server_policies.SERVERS % 'create:trusted_certs', target=target) # TODO(Shao He, Feng) move this policy check to os-availability-zone # extension after refactor it. parse_az = self.compute_api.parse_availability_zone try: # 解析 --availability-zone AZ1:Compute1:Hypervisor1 参数 availability_zone, host, node = parse_az(context, availability_zone) except exception.InvalidInput as err: raise exc.HTTPBadRequest(explanation=six.text_type(err)) if host or node: context.can(server_policies.SERVERS % 'create:forced_host', {}) # NOTE(danms): Don't require an answer from all cells here, as # we assume that if a cell isn't reporting we won't schedule into # it anyway. A bit of a gamble, but a reasonable one. min_compute_version = service_obj.get_minimum_version_all_cells( nova_context.get_admin_context(), ['nova-compute']) # 是否支持 device tagging 功能 supports_device_tagging = (min_compute_version >= DEVICE_TAGGING_MIN_COMPUTE_VERSION) # 两个 Boot from volume 的 block device mapping 版本 block_device_mapping_legacy = server_dict.get('block_device_mapping', []) block_device_mapping_v2 = server_dict.get('block_device_mapping_v2', []) if block_device_mapping_legacy and block_device_mapping_v2: expl = _('Using different block_device_mapping syntaxes ' 'is not allowed in the same request.') raise exc.HTTPBadRequest(explanation=expl) if block_device_mapping_legacy: for bdm in block_device_mapping_legacy: if 'delete_on_termination' in bdm: bdm['delete_on_termination'] = strutils.bool_from_string( bdm['delete_on_termination']) create_kwargs[ 'block_device_mapping'] = block_device_mapping_legacy # Sets the legacy_bdm flag if we got a legacy block device mapping. create_kwargs['legacy_bdm'] = True elif block_device_mapping_v2: # Have to check whether --image is given, see bug 1433609 image_href = server_dict.get('imageRef') image_uuid_specified = image_href is not None try: # Transform the API format of data to the internally used one. # block_device_mapping_v2 的数据结构： # "block_device_mapping_v2": [{ # "boot_index": "0", # "uuid": "ac408821-c95a-448f-9292-73986c790911", # "source_type": "image", # "volume_size": "25", # "destination_type": "volume", # "delete_on_termination": true, # "tag": "disk1", # "disk_bus": "scsi"}] block_device_mapping = [ block_device.BlockDeviceDict.from_api(bdm_dict, image_uuid_specified) for bdm_dict in block_device_mapping_v2] except exception.InvalidBDMFormat as e: raise exc.HTTPBadRequest(explanation=e.format_message()) create_kwargs['block_device_mapping'] = block_device_mapping # Unset the legacy_bdm flag if we got a block device mapping. create_kwargs['legacy_bdm'] = False block_device_mapping = create_kwargs.get("block_device_mapping") if block_device_mapping: # 检查 target 是否支持 create:attach_volume 操做 context.can(server_policies.SERVERS % 'create:attach_volume', target) for bdm in block_device_mapping: if bdm.get('tag', None) and not supports_device_tagging: msg = _('Block device tags are not yet supported.') raise exc.HTTPBadRequest(explanation=msg) # 获取指定的 image uuid # 若是没有 image_href 而且存在 block_device_mapping 则返回 '' 空字符串，Boot from volume 就不须要指定 Image 了 # 若是有 image_href，则 image_uuid = image_href image_uuid = self._image_from_req_data(server_dict, create_kwargs) # NOTE(cyeoh): Although upper layer can set the value of # return_reservation_id in order to request that a reservation # id be returned to the client instead of the newly created # instance information we do not want to pass this parameter # to the compute create call which always returns both. We use # this flag after the instance create call to determine what # to return to the client return_reservation_id = create_kwargs.pop('return_reservation_id', False) # 经过 networks attribute 建立一个 list of requested networks requested_networks = server_dict.get('networks', None) if requested_networks is not None: requested_networks = self._get_requested_networks( requested_networks, supports_device_tagging) # Skip policy check for 'create:attach_network' if there is no # network allocation request. if requested_networks and len(requested_networks) and \ not requested_networks.no_allocate: context.can(server_policies.SERVERS % 'create:attach_network', target) # 获取 flavor object（DB） flavor_id = self._flavor_id_from_req_data(body) try: inst_type = flavors.get_flavor_by_flavor_id( flavor_id, ctxt=context, read_deleted="no") # 是否支持 Cinder Mulit-Attach supports_multiattach = common.supports_multiattach_volume(req) # 跳转到 Compute API 处理，实际上后来是继续跳转到 Conductor 了。 (instances, resv_id) = self.compute_api.create(context, inst_type, image_uuid, display_name=name, display_description=description, availability_zone=availability_zone, forced_host=host, forced_node=node, metadata=server_dict.get('metadata', {}), admin_password=password, requested_networks=requested_networks, check_server_group_quota=True, supports_multiattach=supports_multiattach, **create_kwargs) except (exception.QuotaError, exception.PortLimitExceeded) as error: raise exc.HTTPForbidden( explanation=error.format_message()) except exception.ImageNotFound: msg = _("Can not find requested image") raise exc.HTTPBadRequest(explanation=msg) except exception.KeypairNotFound: msg = _("Invalid key_name provided.") raise exc.HTTPBadRequest(explanation=msg) except exception.ConfigDriveInvalidValue: msg = _("Invalid config_drive provided.") raise exc.HTTPBadRequest(explanation=msg) except (exception.BootFromVolumeRequiredForZeroDiskFlavor, exception.ExternalNetworkAttachForbidden) as error: raise exc.HTTPForbidden(explanation=error.format_message()) except messaging.RemoteError as err: msg = "%(err_type)s: %(err_msg)s" % {'err_type': err.exc_type, 'err_msg': err.value} raise exc.HTTPBadRequest(explanation=msg) except UnicodeDecodeError as error: msg = "UnicodeError: %s" % error raise exc.HTTPBadRequest(explanation=msg) except (exception.CPUThreadPolicyConfigurationInvalid, exception.ImageNotActive, exception.ImageBadRequest, exception.ImageNotAuthorized, exception.FixedIpNotFoundForAddress, exception.FlavorNotFound, exception.FlavorDiskTooSmall, exception.FlavorMemoryTooSmall, exception.InvalidMetadata, exception.InvalidRequest, exception.InvalidVolume, exception.MultiplePortsNotApplicable, exception.InvalidFixedIpAndMaxCountRequest, exception.InstanceUserDataMalformed, exception.PortNotFound, exception.FixedIpAlreadyInUse, exception.SecurityGroupNotFound, exception.PortRequiresFixedIP, exception.NetworkRequiresSubnet, exception.NetworkNotFound, exception.InvalidBDM, exception.InvalidBDMSnapshot, exception.InvalidBDMVolume, exception.InvalidBDMImage, exception.InvalidBDMBootSequence, exception.InvalidBDMLocalsLimit, exception.InvalidBDMVolumeNotBootable, exception.InvalidBDMEphemeralSize, exception.InvalidBDMFormat, exception.InvalidBDMSwapSize, exception.VolumeTypeNotFound, exception.AutoDiskConfigDisabledByImage, exception.ImageCPUPinningForbidden, exception.ImageCPUThreadPolicyForbidden, exception.ImageNUMATopologyIncomplete, exception.ImageNUMATopologyForbidden, exception.ImageNUMATopologyAsymmetric, exception.ImageNUMATopologyCPUOutOfRange, exception.ImageNUMATopologyCPUDuplicates, exception.ImageNUMATopologyCPUsUnassigned, exception.ImageNUMATopologyMemoryOutOfRange, exception.InvalidNUMANodesNumber, exception.InstanceGroupNotFound, exception.MemoryPageSizeInvalid, exception.MemoryPageSizeForbidden, exception.PciRequestAliasNotDefined, exception.RealtimeConfigurationInvalid, exception.RealtimeMaskNotFoundOrInvalid, exception.SnapshotNotFound, exception.UnableToAutoAllocateNetwork, exception.MultiattachNotSupportedOldMicroversion, exception.CertificateValidationFailed) as error: raise exc.HTTPBadRequest(explanation=error.format_message()) except (exception.PortInUse, exception.InstanceExists, exception.NetworkAmbiguous, exception.NoUniqueMatch, exception.MultiattachSupportNotYetAvailable, exception.VolumeTypeSupportNotYetAvailable, exception.CertificateValidationNotYetAvailable) as error: raise exc.HTTPConflict(explanation=error.format_message()) # If the caller wanted a reservation_id, return it if return_reservation_id: return wsgi.ResponseObject({'reservation_id': resv_id}) server = self._view_builder.create(req, instances[0]) # Enables returning of the instance password by the relevant server API calls # such as create, rebuild, evacuate, or rescue. if CONF.api.enable_instance_password: server['server']['adminPass'] = password robj = wsgi.ResponseObject(server) return self._add_location(robj)
上述的参数基本上能够与 Dashboard 上的 Form 表单一一对应：
api
# File: /opt/stack/nova/nova/compute/api.py @hooks.add_hook("create_instance") def create(self, context, instance_type, image_href, kernel_id=None, ramdisk_id=None, min_count=None, max_count=None, display_name=None, display_description=None, key_name=None, key_data=None, security_groups=None, availability_zone=None, forced_host=None, forced_node=None, user_data=None, metadata=None, injected_files=None, admin_password=None, block_device_mapping=None, access_ip_v4=None, access_ip_v6=None, requested_networks=None, config_drive=None, auto_disk_config=None, scheduler_hints=None, legacy_bdm=True, shutdown_terminate=False, check_server_group_quota=False, tags=None, supports_multiattach=False, trusted_certs=None): """Provision instances, sending instance information to the scheduler. The scheduler will determine where the instance(s) go and will handle creating the DB entries. Returns a tuple of (instances, reservation_id) """ if requested_networks and max_count is not None and max_count > 1: # 验证不能指定一个 IP 地址来建立多个虚拟机 self._check_multiple_instances_with_specified_ip( requested_networks) if utils.is_neutron(): # # 验证不能指定一个 Port 来建立多个虚拟机 self._check_multiple_instances_with_neutron_ports( requested_networks) # 验证指定的 AZ 是否为可用域 if availability_zone: available_zones = availability_zones.\ get_availability_zones(context.elevated(), True) if forced_host is None and availability_zone not in \ available_zones: msg = _('The requested availability zone is not available') raise exception.InvalidRequest(msg) # filter_properties 就是一个 Dict 类型对象，如今包含了实参的列表的内容。 filter_properties = scheduler_utils.build_filter_properties( scheduler_hints, forced_host, forced_node, instance_type) return self._create_instance( context, instance_type, image_href, kernel_id, ramdisk_id, min_count, max_count, display_name, display_description, key_name, key_data, security_groups, availability_zone, user_data, metadata, injected_files, admin_password, access_ip_v4, access_ip_v6, requested_networks, config_drive, block_device_mapping, auto_disk_config, filter_properties=filter_properties, legacy_bdm=legacy_bdm, shutdown_terminate=shutdown_terminate, check_server_group_quota=check_server_group_quota, tags=tags, supports_multiattach=supports_multiattach, trusted_certs=trusted_certs) def _create_instance(self, context, instance_type, image_href, kernel_id, ramdisk_id, min_count, max_count, display_name, display_description, key_name, key_data, security_groups, availability_zone, user_data, metadata, injected_files, admin_password, access_ip_v4, access_ip_v6, requested_networks, config_drive, block_device_mapping, auto_disk_config, filter_properties, reservation_id=None, legacy_bdm=True, shutdown_terminate=False, check_server_group_quota=False, tags=None, supports_multiattach=False, trusted_certs=None): """Verify all the input parameters regardless of the provisioning strategy being performed and schedule the instance(s) for creation. """ # Normalize and setup some parameters if reservation_id is None: reservation_id = utils.generate_uid('r') security_groups = security_groups or ['default'] min_count = min_count or 1 max_count = max_count or min_count block_device_mapping = block_device_mapping or [] tags = tags or [] if image_href: # 获取 Image Id 和 Image Metadata image_id, boot_meta = self._get_image(context, image_href) else: # This is similar to the logic in _retrieve_trusted_certs_object. if (trusted_certs or (CONF.glance.verify_glance_signatures and CONF.glance.enable_certificate_validation and CONF.glance.default_trusted_certificate_ids)): msg = _("Image certificate validation is not supported " "when booting from volume") raise exception.CertificateValidationFailed(message=msg) image_id = None # 若是没有指定 Image 的话就获取 block device 的 Metadata boot_meta = self._get_bdm_image_metadata( context, block_device_mapping, legacy_bdm) # ？？？ self._check_auto_disk_config(image=boot_meta, auto_disk_config=auto_disk_config) # 进一步验证和转换虚拟机建立参数 base_options, max_net_count, key_pair, security_groups, \ network_metadata = self._validate_and_build_base_options( context, instance_type, boot_meta, image_href, image_id, kernel_id, ramdisk_id, display_name, display_description, key_name, key_data, security_groups, availability_zone, user_data, metadata, access_ip_v4, access_ip_v6, requested_networks, config_drive, auto_disk_config, reservation_id, max_count) # max_net_count is the maximum number of instances requested by the # user adjusted for any network quota constraints, including # consideration of connections to each requested network # 若是最大的 network 数量小于最小的虚拟机数量，则触发异常 if max_net_count < min_count: raise exception.PortLimitExceeded() elif max_net_count < max_count: LOG.info("max count reduced from %(max_count)d to " "%(max_net_count)d due to network port quota", {'max_count': max_count, 'max_net_count': max_net_count}) max_count = max_net_count # 进一步检查 Boot from volume 的 block device 的可用性 block_device_mapping = self._check_and_transform_bdm(context, base_options, instance_type, boot_meta, min_count, max_count, block_device_mapping, legacy_bdm) # We can't do this check earlier because we need bdms from all sources # to have been merged in order to get the root bdm. # 进一步检查 quota 和 image 的可用性 self._checks_for_create_and_rebuild(context, image_id, boot_meta, instance_type, metadata, injected_files, block_device_mapping.root_bdm()) # 转换为多个虚拟机为 InstanceGroup 数据结构 instance_group = self._get_requested_instance_group(context, filter_properties) # 转换为 TagList 数据结构 tags = self._create_tag_list_obj(context, tags) # 将诸多建立参数封装到 instances_to_build 列表类型对象中 instances_to_build = self._provision_instances( context, instance_type, min_count, max_count, base_options, boot_meta, security_groups, block_device_mapping, shutdown_terminate, instance_group, check_server_group_quota, filter_properties, key_pair, tags, trusted_certs, supports_multiattach, network_metadata) instances = [] request_specs = [] build_requests = [] for rs, build_request, im in instances_to_build: build_requests.append(build_request) instance = build_request.get_new_instance(context) instances.append(instance) request_specs.append(rs) if CONF.cells.enable: # NOTE(danms): CellsV1 can't do the new thing, so we # do the old thing here. We can remove this path once # we stop supporting v1. for instance in instances: # 建立 Instance 数据库对象 instance.create() # NOTE(melwitt): We recheck the quota after creating the objects # to prevent users from allocating more resources than their # allowed quota in the event of a race. This is configurable # because it can be expensive if strict quota limits are not # required in a deployment. # 再一次检查资源配额 if CONF.quota.recheck_quota: try: compute_utils.check_num_instances_quota( context, instance_type, 0, 0, orig_num_req=len(instances)) except exception.TooManyInstances: with excutils.save_and_reraise_exception(): # Need to clean up all the instances we created # along with the build requests, request specs, # and instance mappings. self._cleanup_build_artifacts(instances, instances_to_build) self.compute_task_api.build_instances(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) else: self.compute_task_api.schedule_and_build_instances( context, build_requests=build_requests, request_spec=request_specs, image=boot_meta, admin_password=admin_password, injected_files=injected_files, requested_networks=requested_networks, block_device_mapping=block_device_mapping, tags=tags) return instances, reservation_id def _validate_and_build_base_options(self, context, instance_type, boot_meta, image_href, image_id, kernel_id, ramdisk_id, display_name, display_description, key_name, key_data, security_groups, availability_zone, user_data, metadata, access_ip_v4, access_ip_v6, requested_networks, config_drive, auto_disk_config, reservation_id, max_count): """Verify all the input parameters regardless of the provisioning strategy being performed. """ # 肯定 Flavor 可用 if instance_type['disabled']: raise exception.FlavorNotFound(flavor_id=instance_type['id']) # 肯定 user_data 数据编码格式为 Base64 if user_data: try: base64utils.decode_as_bytes(user_data) except TypeError: raise exception.InstanceUserDataMalformed() # When using Neutron, _check_requested_secgroups will translate and # return any requested security group names to uuids. security_groups = ( self._check_requested_secgroups(context, security_groups)) # Note: max_count is the number of instances requested by the user, # max_network_count is the maximum number of instances taking into # account any network quotas max_network_count = self._check_requested_networks(context, requested_networks, max_count) # Choose kernel and ramdisk appropriate for the instance. # ramdisk（虚拟内存盘）是一种将内存模拟成硬盘来使用的技术，能够在内存启动虚拟机。 kernel_id, ramdisk_id = self._handle_kernel_and_ramdisk( context, kernel_id, ramdisk_id, boot_meta) # 依旧返回是布尔值类型 config_drive = self._check_config_drive(config_drive) # 经过 keypair name 获取 keypair data if key_data is None and key_name is not None: key_pair = objects.KeyPair.get_by_name(context, context.user_id, key_name) key_data = key_pair.public_key else: key_pair = None # 获取系统盘设备的名称（可能从 Image 获取或者从 Volume 获取） root_device_name = block_device.prepend_dev( block_device.properties_root_device_name( boot_meta.get('properties', {}))) try: # 此处的 image 是一个抽象概念，表示启动操做系统的系统盘。将 Image File 和 Volume 统一为 ImageMeta 对象。 image_meta = objects.ImageMeta.from_dict(boot_meta) except ValueError as e: # there must be invalid values in the image meta properties so # consider this an invalid request msg = _('Invalid image metadata. Error: %s') % six.text_type(e) raise exception.InvalidRequest(msg) # 从 Flavor properties 和 Image properties 获取 NUMA 属性 numa_topology = hardware.numa_get_constraints( instance_type, image_meta) system_metadata = {} # PCI requests come from two sources: instance flavor and # requested_networks. The first call in below returns an # InstancePCIRequests object which is a list of InstancePCIRequest # objects. The second call in below creates an InstancePCIRequest # object for each SR-IOV port, and append it to the list in the # InstancePCIRequests object # PCI requests come from two sources: instance flavor and requested_networks. # 从 Flavor 获取 PCI 设备 pci_request_info = pci_request.get_pci_requests_from_flavor( instance_type) # ？？？ network_metadata = self.network_api.create_resource_requests( context, requested_networks, pci_request_info) # base_options 的数据基本就是 instances 数据库表的属性。 base_options = { 'reservation_id': reservation_id, 'image_ref': image_href, 'kernel_id': kernel_id or '', 'ramdisk_id': ramdisk_id or '', 'power_state': power_state.NOSTATE, 'vm_state': vm_states.BUILDING, 'config_drive': config_drive, 'user_id': context.user_id, 'project_id': context.project_id, 'instance_type_id': instance_type['id'], 'memory_mb': instance_type['memory_mb'], 'vcpus': instance_type['vcpus'], 'root_gb': instance_type['root_gb'], 'ephemeral_gb': instance_type['ephemeral_gb'], 'display_name': display_name, 'display_description': display_description, 'user_data': user_data, 'key_name': key_name, 'key_data': key_data, 'locked': False, 'metadata': metadata or {}, 'access_ip_v4': access_ip_v4, 'access_ip_v6': access_ip_v6, 'availability_zone': availability_zone, 'root_device_name': root_device_name, 'progress': 0, 'pci_requests': pci_request_info, 'numa_topology': numa_topology, 'system_metadata': system_metadata} options_from_image = self._inherit_properties_from_image( boot_meta, auto_disk_config) base_options.update(options_from_image) # return the validated options and maximum number of instances allowed # by the network quotas return (base_options, max_network_count, key_pair, security_groups, network_metadata) def _provision_instances(self, context, instance_type, min_count, max_count, base_options, boot_meta, security_groups, block_device_mapping, shutdown_terminate, instance_group, check_server_group_quota, filter_properties, key_pair, tags, trusted_certs, supports_multiattach, network_metadata=None): # Check quotas num_instances = compute_utils.check_num_instances_quota( context, instance_type, min_count, max_count) security_groups = self.security_group_api.populate_security_groups( security_groups) self.security_group_api.ensure_default(context) LOG.debug("Going to run %s instances...", num_instances) instances_to_build = [] try: for i in range(num_instances): # Create a uuid for the instance so we can store the # RequestSpec before the instance is created. instance_uuid = uuidutils.generate_uuid() # Store the RequestSpec that will be used for scheduling. # 将于 scheduling 相关的参数都封装到 RequestSpec 对象，便于在 Nova Scheduler 中应用。 req_spec = objects.RequestSpec.from_components(context, instance_uuid, boot_meta, instance_type, base_options['numa_topology'], base_options['pci_requests'], filter_properties, instance_group, base_options['availability_zone'], security_groups=security_groups) # 若是是 Boot from Volume，则使用系统盘做为操做系统的根盘 if block_device_mapping: # Record whether or not we are a BFV instance root = block_device_mapping.root_bdm() # 标记为 Boot from volume req_spec.is_bfv = bool(root and root.is_volume) else: # If we have no BDMs, we're clearly not BFV req_spec.is_bfv = False # NOTE(danms): We need to record num_instances on the request # spec as this is how the conductor knows how many were in this # batch. req_spec.num_instances = num_instances # 建立 RequestSpec 数据库记录 req_spec.create() # NOTE(stephenfin): The network_metadata field is not persisted # and is therefore set after 'create' is called. if network_metadata: req_spec.network_metadata = network_metadata # Create an instance object, but do not store in db yet. instance = objects.Instance(context=context) instance.uuid = instance_uuid instance.update(base_options) instance.keypairs = objects.KeyPairList(objects=[]) if key_pair: instance.keypairs.objects.append(key_pair) instance.trusted_certs = self._retrieve_trusted_certs_object( context, trusted_certs) instance = self.create_db_entry_for_new_instance(context, instance_type, boot_meta, instance, security_groups, block_device_mapping, num_instances, i, shutdown_terminate, create_instance=False) # 肯定 Block Device 时可用的，并设定其 Size 且与 Instance 关联起来 block_device_mapping = ( self._bdm_validate_set_size_and_instance(context, instance, instance_type, block_device_mapping, supports_multiattach)) instance_tags = self._transform_tags(tags, instance.uuid) # 将于虚拟机建立（启动）相关的参数封装到 BuildRequest 对象 build_request = objects.BuildRequest(context, instance=instance, instance_uuid=instance.uuid, project_id=instance.project_id, block_device_mappings=block_device_mapping, tags=instance_tags) build_request.create() # Create an instance_mapping. The null cell_mapping indicates # that the instance doesn't yet exist in a cell, and lookups # for it need to instead look for the RequestSpec. # cell_mapping will be populated after scheduling, with a # scheduling failure using the cell_mapping for the special # cell0. # 将于虚拟机定位（cells）相关的参数封装到 InstanceMapping 对象 inst_mapping = objects.InstanceMapping(context=context) inst_mapping.instance_uuid = instance_uuid inst_mapping.project_id = context.project_id inst_mapping.cell_mapping = None inst_mapping.create() instances_to_build.append( (req_spec, build_request, inst_mapping)) if instance_group: if check_server_group_quota: try: objects.Quotas.check_deltas( context, {'server_group_members': 1}, instance_group, context.user_id) except exception.OverQuota: msg = _("Quota exceeded, too many servers in " "group") raise exception.QuotaError(msg) members = objects.InstanceGroup.add_members( context, instance_group.uuid, [instance.uuid]) # NOTE(melwitt): We recheck the quota after creating the # object to prevent users from allocating more resources # than their allowed quota in the event of a race. This is # configurable because it can be expensive if strict quota # limits are not required in a deployment. if CONF.quota.recheck_quota and check_server_group_quota: try: objects.Quotas.check_deltas( context, {'server_group_members': 0}, instance_group, context.user_id) except exception.OverQuota: objects.InstanceGroup._remove_members_in_db( context, instance_group.id, [instance.uuid]) msg = _("Quota exceeded, too many servers in " "group") raise exception.QuotaError(msg) # list of members added to servers group in this iteration # is needed to check quota of server group during add next # instance instance_group.members.extend(members) # In the case of any exceptions, attempt DB cleanup except Exception: with excutils.save_and_reraise_exception(): self._cleanup_build_artifacts(None, instances_to_build) return instances_to_build
至此，POST /servers 在 nova-api service 的工做流程基本就完成了，总的来讲主要作了两件事情：校验 和 转换。安全
- API 接口的版本控制、数据类型校验（e.g. validation.schema）
- 用户操做意图许可校验（e.g. context.can、supports_device_tagging、supports_multiattach）
- 虚拟机关联资源的可用性校验
- 用户输入数据整理、概括、分类并转化为程序内部使用的数据结构（对象）
后面经过 self.compute_task_api 调用进入到 nova-conductor service 的工做流程。数据结构
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