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[Matt Riedemann <mriedem.os@xxxxxxxxx>]

** Also affects: nova/newton
   Importance: Undecided
       Status: New

** Also affects: nova/ocata
   Importance: Undecided
       Status: New

** Summary changed:

- VM evacuation is broken with shared torage if VM console.log is not owned by nova
+ VM evacuation is broken with shared storage if VM console.log is not owned by nova

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https://bugs.launchpad.net/bugs/1691831

Title:
  VM evacuation is broken with shared storage if VM console.log is not
  owned by nova

Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) newton series:
  In Progress
Status in OpenStack Compute (nova) ocata series:
  In Progress

Bug description:
  On my Ocata deployment (with a shared storage between my KVMs hypervisors), the following worflow is failing:
   * stop nova-compute on a KVM hypervisor
   * stop a VM on the KVM hypervisor using virsh destroy
   * evacuate the VM ... which fails with the stacktrace:

  ERROR nova.compute.manager [req-dcb547e3-5f98-488e-8dbf-ad4453ce82ac 7e6f47b9c6cf4994bb38a2eb3ad6243f 920a4480938349eca2651c140ce33fdd - - -] [instance: a129ab8f-c224-4df2-8134-6716cfe89acf] Setting instance vm_state to ERROR
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf] Traceback (most recent call last):
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 6717, in _error_out_instance_on_exception
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     yield
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2751, in rebuild_instance
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     bdms, recreate, on_shared_storage, preserve_ephemeral)
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2795, in _do_rebuild_instance_with_claim
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     self._do_rebuild_instance(*args, **kwargs)
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2910, in _do_rebuild_instance
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     self._rebuild_default_impl(**kwargs)
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2673, in _rebuild_default_impl
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     block_device_info=new_block_device_info)
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2689, in spawn
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     self._ensure_console_log_for_instance(instance)
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2961, in _ensure_console_log_for_instance
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     libvirt_utils.file_open(console_file, 'a').close()
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/utils.py", line 350, in file_open
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]     return open(*args, **kwargs)
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf] IOError: [Errno 13] Permission denied: '/var/lib/nova/instances/a129ab8f-c224-4df2-8134-6716cfe89acf/console.log'
  ERROR nova.compute.manager [instance: a129ab8f-c224-4df2-8134-6716cfe89acf]

  
  After some investigation:

  _ensure_console_log_for_instance[1] ensures console.log existence. A
  change[2] updated this method in order to succeed if the file exists
  without nova being able to open it by ignoring EPERM erros (errno 1,
  "operation not permitted") but it should ignore EACCES errors (errno
  13, "permission denied").

  
   >>> open('/etc/shadow')
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   IOError: [Errno 13] Permission denied: '/etc/shadow'

  
  EACCES errors are raised when you cannot do something because of insufficient permissions, EPERM are raised when you cannot do something (even with root account).

  
  [1] nova.virt.libvirt.driver
  [2] https://review.openstack.org/392643

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