ML2 port binding failure logging too subtle

[Assaf Muller]

When manually switching over segmentation method (IE: VXLAN to VLANs), any misconfiguration of the bridge mappings on a hypervisor will result in ML2 port binding failure on that host. The only log message that appears is a warning. I think that it should be raised to an error, and the port binding failure itself via agent based mechanism drivers should say exactly what's wrong. What is the network's physical network, and what physical networks the agent reported.

[Irena Berezovsky (irenab)]

I am not sure that changing warning into error is correct approach. Since with ML2 plugin it's possible to have number of mechanism drivers that are capable to bind port, it maybe be the case that where one MD fails, other one succeeds. While more information regarding the binding refuse is required, I would suggest to leave the Warning log severity level.

[Assaf Muller (amuller)]

@Irena: Absolutely. A complete binding failure (IE: All drivers failed) is an error, while one driver failing is very different, and should be logged as you said.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/125115
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=72e285ac1aad2f5a4b246435cf4d4b0126fb3431
Submitter: Jenkins
Branch: master

commit 72e285ac1aad2f5a4b246435cf4d4b0126fb3431
Author: Assaf Muller <email address hidden>
Date: Tue Sep 30 19:31:57 2014 +0300

    Improve agent-based flat/vlan ml2 port binding failure logging

    Port binding failure is an error and should be reported as such.
    Additionally, if a port binding fails on a host due to missing
    bridge mappings, it's currently quite a mystery to find out. This
    should be logged instead of requiring users to debug code. Not
    everyone enjoys debugging Python, as weird as that is!

    I refactored out the common code in check_segment_for_agent
    in order to make logging more robust for all agent-based mechanism
    drivers. The OVS and LB mech drivers already log due to a bridge
    mappings mismatch and the other agent based mech drivers
    will now log as well.

    Closes-Bug: #1377710
    Change-Id: I451a0763908adcd845721e8cda7f3189da6c8b81