【OpenStack】源码级深入了解删除虚拟机操作

首先看一下虚拟机有多少种状态：(/nova/compute/vmstates.py)

 ACTIVE = 'active'  # VM is running
 BUILDING = 'building'  # VM only exists in DB
 PAUSED = 'paused'
 SUSPENDED = 'suspended'  # VM is suspended to disk.
 STOPPED = 'stopped'  # VM is powered off, the disk image is still there.
 RESCUED = 'rescued'  # A rescue image is running with the original VM image
 # attached.
 RESIZED = 'resized'  # a VM with the new size is active. The user is expected
 # to manually confirm or revert.

 SOFT_DELETED = 'soft-delete'  # VM is marked as deleted but the disk images are
 # still available to restore.
 DELETED = 'deleted'  # VM is permanently deleted.

 ERROR = 'error'

 SHELVED = 'shelved'  # VM is powered off, resources still on hypervisor
 SHELVED_OFFLOADED = 'shelved_offloaded'  # VM and associated resources are
 # not on hypervisor

 ALLOW_SOFT_REBOOT = [ACTIVE]  # states we can soft reboot from
 ALLOW_HARD_REBOOT = ALLOW_SOFT_REBOOT + [STOPPED, PAUSED, SUSPENDED, ERROR]
 # states we allow hard reboot from

 ALLOW_TRIGGER_CRASH_DUMP = [ACTIVE, PAUSED, RESCUED, RESIZED, ERROR]
 # states we allow to trigger crash dump

 ALLOW_RESOURCE_REMOVAL = [DELETED, SHELVED_OFFLOADED]
 # states we allow resources to be freed in

在删除虚拟机时，会根据虚拟机状态来进行不同的操作。可以看出deleted和shelved_offloaded两种状态下虚拟机资源完全释放，而shelved