LLDP agent driver exception on empty bridge

[Steven Webster]

Brief Description
-----------------
A sysinv agent exception may be seen every 6 minutes if a user/process creates an empty bridge with no attached ports. This would not normally be the case in the default StarlingX network topology, but may
be seen by developers/experimenters of other future features.

Severity
--------
Major

Steps to Reproduce
------------------
ovs-vsctl add-br br0
wait up to 6 minutes and monitor the sysinv.log

Expected Behavior
------------------
No exception to occur.
The LLDP agent code should be more robust to handle unexpected json output.

Actual Behavior
----------------
An exception occurs in the default sysinv LLDP agent driver.

Reproducibility
---------------
100% Reproducible

System Configuration
--------------------
Any

Branch/Pull Time/Commit
-----------------------
master 11/7/2018

Timestamp/Logs
--------------

2018-11-06 20:23:18.360 8968 ERROR sysinv.agent.lldp.manager [-] Sysinv LLDP agent driver 'ovs' failed in lldp_agents_list
2018-11-06 20:23:18.360 8968 ERROR sysinv.agent.lldp.manager [-] string index out of range
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager Traceback (most recent call last):
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager File "/usr/lib64/python2.7/site-packages/sysinv/agent/lldp/manager.py", line 140, in lldp_agents_list
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager raise_orig_exc=True)
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager File "/usr/lib64/python2.7/site-packages/sysinv/agent/lldp/manager.py", line 75, in _call_drivers_and_return_array
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager ret = ret + method()
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager File "/usr/lib64/python2.7/site-packages/sysinv/agent/lldp/drivers/ovs/driver.py", line 161, in lldp_agents_list
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager self.lldp_ovs_update_flows()
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager File "/usr/lib64/python2.7/site-packages/sysinv/agent/lldp/drivers/ovs/driver.py", line 114, in lldp_ovs_update_flows
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager port_bridge_map = self.lldp_ovs_get_port_bridge_map()
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager File "/usr/lib64/python2.7/site-packages/sysinv/agent/lldp/drivers/ovs/driver.py", line 78, in lldp_ovs_get_port_bridge_map
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager value = port[1]
2018-11-06 20:23:18.360 8968 TRACE sysinv.agent.lldp.manager IndexError: string index out of range

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/617848

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/617848
Committed: https://git.openstack.org/cgit/openstack/stx-config/commit/?id=5cd3d0dc02a90a83a958949859c8c8743408d81c
Submitter: Zuul
Branch: master

commit 5cd3d0dc02a90a83a958949859c8c8743408d81c
Author: Steven Webster <email address hidden>
Date: Wed Oct 31 17:01:54 2018 -0400

    Make LLDP OVS agent driver more robust to json output

    An issue was seen recently in which a bridge with a single port caused
    an exception in the LLDP driver, as the json output did not match what
    was expected. In this case, the port was a simple uuid/value list
    rather than a list of uuid/value lists.

    ie.

    ["br-ex",["uuid","val1"]]

    vs

    ["br-int",["set",[["uuid","val2"],["uuid","val3"]]]]

    This commit adds a fix to handle both cases, and also adds
    robustness to gracefully catch similar issues of unexpected json
    output.

    Closes-Bug: #1802118
    Change-Id: I73189f138a543f34e467f51e18544b521a00457c
    Signed-off-by: Steven Webster <email address hidden>