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[Trung Trinh <trung.t.trinh@xxxxxxxxxxxxxx>]

Public bug reported:

Version: stable/juno

Description:
This bug report is created to separate two issues found in this link: https://bugs.launchpad.net/nova/+bug/1390033.
The purpose is to fix at first the bug that the "if not host:" never holds in function get_instance_availability_zone() of module nova.availability_zones in case host is None. This is because str(None) is never interpreted False.

For proof, please look at the output of the Python interactive session:

Python 2.7.6 (default, Mar 22 2014, 22:59:56)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> host = str(None)
>>> print host
None
>>> if not host:
.......print "if not host"
....else:
...... print "else"
...
else

>>> var = None
>>> if not var:
.......print "if not var"
....else:
.......print "else"
...
if not var

So, it can be seen that str(None) returns an object whose value is None,
but it is not interpreted False as expected!

** Affects: nova
     Importance: Undecided
     Assignee: Trung Trinh (trung-t-trinh)
         Status: In Progress

** Description changed:

  Version: stable/juno
  
  Description:
  This bug report is created to separate two issues found in this link: https://bugs.launchpad.net/nova/+bug/1390033.
  The purpose is to fix at first the bug that the "if not host:" never holds in function get_instance_availability_zone() of module nova.availability_zones in case host is None. This is because str(None) is never interpreted False.
  
  For proof, please look at the output of the Python interactive session:
  
  Python 2.7.6 (default, Mar 22 2014, 22:59:56)
  [GCC 4.8.2] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  >>> host = str(None)
  >>> print host
  None
  >>> if not host:
- .......... print "if not host"
- ........else:
- .......... print "else"
+ .......print "if not host"
+ ....else:
+ ...... print "else"
  ...
  else
  
  >>> var = None
  >>> if not var:
- .......... print "if not var"
- ....... else:
- .......... print "else"
+ .......print "if not var"
+ ....else:
+ .......print "else"
  ...
  if not var
  
  So, it can be seen that str(None) returns an object whose value is None,
  but it is not interpreted False as expected!

** Changed in: nova
     Assignee: (unassigned) => Trung Trinh (trung-t-trinh)

** Changed in: nova
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/1414556

Title:
  "if not host:" never holds in function
  get_instance_availability_zone() of module nova.availability_zones

Status in OpenStack Compute (Nova):
  In Progress

Bug description:
  Version: stable/juno

  Description:
  This bug report is created to separate two issues found in this link: https://bugs.launchpad.net/nova/+bug/1390033.
  The purpose is to fix at first the bug that the "if not host:" never holds in function get_instance_availability_zone() of module nova.availability_zones in case host is None. This is because str(None) is never interpreted False.

  For proof, please look at the output of the Python interactive
  session:

  Python 2.7.6 (default, Mar 22 2014, 22:59:56)
  [GCC 4.8.2] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  >>> host = str(None)
  >>> print host
  None
  >>> if not host:
  .......print "if not host"
  ....else:
  ...... print "else"
  ...
  else

  >>> var = None
  >>> if not var:
  .......print "if not var"
  ....else:
  .......print "else"
  ...
  if not var

  So, it can be seen that str(None) returns an object whose value is
  None, but it is not interpreted False as expected!

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