StopIteration causes check_nova_services to finish abruptly

[Alvaro Uria]

root@juju-3d3206-0-lxd-5:~# sudo -u nagios /usr/local/lib/nagios/plugins/check_nova_services.py
<function check_nova_services at 0x7f2c9a791848> raised unknown exception '<type 'exceptions.StopIteration'>'
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Traceback (most recent call last):
  File "/usr/local/lib/nagios/plugins/nagios_plugin.py", line 32, in try_check
    function(*args, **kwargs)
  File "/usr/local/lib/nagios/plugins/check_nova_services.py", line 66, in check_nova_services
    services_compute))
  File "/usr/local/lib/nagios/plugins/check_nova_services.py", line 21, in check_hosts_up
    host_svc = (svc for svc in services_compute if svc['host'] ==
StopIteration
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Expectation:
Iteration should be caught and issue a "continue" statement.
https://git.launchpad.net/charm-openstack-service-checks/tree/files/plugins/check_nova_services.py#n21

try:
  ...
except StopIteration as e:
  continue

Alternatively, and since a single item is expected, a list could be created (no expectation of mem exhaustion for lazy load).

[Zachary Zehring (zzehring)]

Encountered this error as well. For my case, if no services (svc) is returned by list comprehension, the error is thrown. This is occurring when there's a host in a host aggregate but no corresponding OS service running on it.