fix [Errno 13] Permission denied: '/var/log/glance/api.log'

root@node1 glance]# su -s /bin/sh -c "glance-manage db_sync" glance
Traceback (most recent call last):
  File "/usr/bin/glance-manage", line 10, in <module>
    sys.exit(main())
  File "/usr/lib/python2.6/site-packages/glance/cmd/manage.py", line 253, in main
    log.setup('glance')
  File "/usr/lib/python2.6/site-packages/glance/openstack/common/log.py", line 440, in setup
    _setup_logging_from_conf(product_name, version)
  File "/usr/lib/python2.6/site-packages/glance/openstack/common/log.py", line 504, in _setup_logging_from_conf
    filelog = logging.handlers.WatchedFileHandler(logpath)
  File "/usr/lib64/python2.6/logging/handlers.py", line 377, in __init__
    logging.FileHandler.__init__(self, filename, mode, encoding, delay)
  File "/usr/lib64/python2.6/logging/__init__.py", line 827, in __init__
    StreamHandler.__init__(self, self._open())
  File "/usr/lib64/python2.6/logging/__init__.py", line 846, in _open
    stream = open(self.baseFilename, self.mode)
IOError: [Errno 13] Permission denied: '/var/log/glance/api.log'
[root@node1 glance]# chmod 777 /var/log/glance/api.log
[root@node1 glance]# su -s /bin/sh -c "glance-manage db_sync" glance
[root@node1 glance]# echo $?