config-changed fails if no nrpe is present

[Jorge Niedbalski]

After r46 , on a system without nrpe enabled, the following error is raised after applying a config change.

Juju status:

    units:
      az2-compute/0:
        agent-state: error
        agent-state-info: 'hook failed: "config-changed"'
        agent-version: 1.20.11.1
        machine: "28"
        public-address: xxx
          ceilometer-agent/3:
            upgrading-from: local:trusty/ceilometer-agent-22
            agent-state: started
            agent-version: 1.20.11.1
            public-address: xxx
      az2-compute/1:

Backtrace:

2015-04-09 05:36:42 INFO juju-log Check command not found: check_upstart_job
2015-04-09 05:36:42 INFO config-changed Traceback (most recent call last):
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/config-changed", line 328, in <module>
2015-04-09 05:36:42 INFO config-changed main()
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/config-changed", line 322, in main
2015-04-09 05:36:42 INFO config-changed hooks.execute(sys.argv)
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/charmhelpers/core/hookenv.py", line 544, in execute
2015-04-09 05:36:42 INFO config-changed self._hooks[hook_name]()
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/charmhelpers/core/host.py", line 312, in wrapped_f
2015-04-09 05:36:42 INFO config-changed f(*args)
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/config-changed", line 119, in config_changed
2015-04-09 05:36:42 INFO config-changed update_nrpe_config()
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/config-changed", line 317, in update_nrpe_config
2015-04-09 05:36:42 INFO config-changed nrpe_setup.write()
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/charmhelpers/contrib/charmsupport/nrpe.py", line 244, in write
2015-04-09 05:36:42 INFO config-changed self.nagios_servicegroups)
2015-04-09 05:36:42 INFO config-changed File "/var/lib/juju/agents/unit-az2-compute-4/charm/hooks/charmhelpers/contrib/charmsupport/nrpe.py", line 167, in write
2015-04-09 05:36:42 INFO config-changed with open(nrpe_check_file, 'w') as nrpe_check_config:
2015-04-09 05:36:42 INFO config-changed IOError: [Errno 2] No such file or directory: '/etc/nagios/nrpe.d/check_neutron-plugin-openvswitch-agent.cfg'
2015-04-09 05:36:42 ERROR juju.worker.uniter uniter.go:486 hook failed: exit status 1