openstack：nova中“从镜像起动”创建虚拟机的流程

openstack：nova中“从镜像启动”创建虚拟机的流程

openstack版本为K版本。

从镜像启动虚拟机之：创建镜像+创建虚拟机并开机的流程

nova.api.openstack.compute.servers.Controller.create
->nova.compute.api.API.create
->nova.compute.api.API._create_instance
->nova.comductor.ComputeTaskAPI.build_instances
->nova.conductor. rpcapi.ComputeTaskAPI.build_instances
->nova.conductor. manager.ComputeTaskAPI.build_instances
->nova.compute.rpcapi.ComputeAPI.build_and_run_instance
->nova.compute.manager.ComputeAPI.build_and_run_instance
->nova.compute.manager.ComputeAPI._locked_do_build_and_run_instance
->nova.compute.manager.ComputeAPI._do_build_and_run_instance
->nova.compute.manager.ComputeAPI._build_and_run_instance
->nova.virt.libvirt.driver.LibvirtDriver.spawn
->Nova.virt.libvirt.driver._create_image //创建系统盘
 ->Nova.virt.libvirt.driver._try_fetch_image_cache
 ->Nova.virt.libvirt.imagebackend.Image.cache
 ->Nova.virt.libvirt.imagebackend.Qcow2.create_image
   ->Nova.virt.libvirt.imagebackend.Qcow2.create_image：prepare_template即fetch_image
     ->Nova.virt.libvirt.utils.fetch_image
       ->Nova.virt.images.fetch_to_raw
         ->Nova.virt.images.fetch  	 	#下载系统镜像到/var/lib/nova/instances/_base/目录
           ->nova.image.glance.GlanceImageService.download
             ->nova.image.glance.GlanceClientWrapper.call
  ->Nova.virt.images.convert_image    #若镜像不是raw格式，且nova.conf中force_raw_images=True，则将backing file强制转换为raw格式
  ->Nova.virt.libvirt.imagebackend.Qcow2.create_image：copy_qcow2_image
  ->nova.virt.libvirt.utils.create_cow_image
->nova.virt.libvirt.driver._get_guest_xml //创建虚拟机的xml文件
->nova.virt.libvirt.driver._create_domain_and_network //创建主机和主机网络
->nova.virt.driver.block_device_info_get_mapping //块设备映射
->nova.virt.driver.get_image_from_system_metadata //获取镜像和元数据
->nova.virt.libvirt.driver.LibvirtDriver.attach_volume //挂载云硬盘
->nova.virt.libvirt.firewall.prepare_instance_filter //准备网络
->nova.virt.libvirt.driver.LibvirtDriver._create_domain //创建主机
->nova.virt.libvirt.driver.LibvirtDriver._create_domain ：domain = self._conn.defineXML
->/usr/lib64/python2.7/site-packages/libvirt.py：defineXML
->nova.virt.libvirt.firewall.apply_instance_filter//使用网络，实际上全在prepare_instance_filter中做了，这里都是空
->nova.virt.libvirt.driver.power_on //开机