[metering agent] Failed to get any traffic data if the first chain is missing

[Feilong Wang]

Based on current implement, if there is any reason caused the chain of metering label is missing, the whole function of iptables_driver.get_traffic_counters() will be broken, see https://github.com/openstack/neutron/blob/master/neutron/services/metering/drivers/iptables/iptables_driver.py#L275

2015-02-03 22:47:25.486 6384 ERROR neutron.services.metering.agents.metering_agent [req-47dbfc00-1812-423a-9f68-ce26dc54243a None] Driver neutron.services.metering.drivers.iptables.iptables_driver.IptablesMeteringDriver:get_traffic_counters runtime error
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent Traceback (most recent call last):
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent File "/usr/lib/python2.7/dist-packages/neutron/services/metering/agents/metering_agent.py", line 177, in _invoke_driver
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent return getattr(self.metering_driver, func_name)(context, meterings)
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent File "/usr/lib/python2.7/dist-packages/neutron/common/log.py", line 34, in wrapper
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent return method(*args, **kwargs)
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent File "/usr/lib/python2.7/dist-packages/neutron/services/metering/drivers/iptables/iptables_driver.py", line 275, in get_traffic_counters
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent chain, wrap=False, zero=True)
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/iptables_manager.py", line 627, in get_traffic_counters
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent root_helper=self.root_helper))
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/utils.py", line 82, in execute
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent raise RuntimeError(m)
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent RuntimeError:
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent Command: ['sudo', 'neutron-rootwrap', '/etc/neutron/rootwrap.conf', 'ip', 'netns', 'exec', 'qrouter-a9123cfe-9277-49ea-a2c5-1c9581e277d2', 'iptables', '-t', 'filter', '-L', 'neutron-meter-l-c760740b-33a', '-n', '-v', '-x', '-Z']
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent Exit code: 1
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent Stdout: ''
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent Stderr: 'iptables: No chain/target/match by that name.\n'
2015-02-03 22:47:25.486 6384 TRACE neutron.services.metering.agents.metering_agent

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/156198

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/156198
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=c3b7f1b2ae7af995f4815e3571c9828683dc0db7
Submitter: Jenkins
Branch: master

commit c3b7f1b2ae7af995f4815e3571c9828683dc0db7
Author: Fei Long Wang <email address hidden>
Date: Tue Feb 17 00:58:45 2015 +1300

    Fix metering agent failure when chain missing

    The metering agent will fail if one of the iptables chains
    is missing, which will cause errors extracting data from
    all the other chains. Add a simple try/except to let the
    loop continue.

    Closes-Bug: #1421037

    Change-Id: I370ee0e2cc58ca7e1c5ef9bf4dbcce5abf7545a1