L3-agent does not work with linux bridge

[Gary Kotton]

openstack@openstack:~/devstack$ sudo python /opt/stack/quantum/bin/quantum-l3-agent --config-file /etc/quantum/quantum.conf --config-file=/etc/quantum/l3_agent.ini
2012-09-11 02:53:17 DEBUG [quantum.agent.linux.utils] Running command: ip -o link show br-ex
2012-09-11 02:53:17 DEBUG [quantum.agent.linux.utils]
Command: ['ip', '-o', 'link', 'show', 'br-ex']
Exit code: 1
Stdout: ''
Stderr: 'Device "br-ex" does not exist.\n'
Traceback (most recent call last):
  File "/opt/stack/quantum/bin/quantum-l3-agent", line 20, in <module>
    main()
  File "/opt/stack/quantum/quantum/agent/l3_agent.py", line 505, in main
    mgr = L3NATAgent(conf)
  File "/opt/stack/quantum/quantum/agent/l3_agent.py", line 122, in __init__
    % self.conf.external_network_bridge)
Exception: external network bridge 'br-ex' does not exist
openstack@openstack:~/devstack$

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/12770

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/12770
Committed: http://github.com/openstack/quantum/commit/93c7147bdb677e30a5564088c18c4b763fd588c4
Submitter: Jenkins
Branch: master

commit 93c7147bdb677e30a5564088c18c4b763fd588c4
Author: Gary Kotton <email address hidden>
Date: Tue Sep 11 06:32:12 2012 +0000

    Ensures that the Linux Bridge Plugin runs with L3 agent

    Fixes bug 1048968

    1. The external interface for the linux bridge will be created at run time.
    The configuration parameter external_network_bridge should be set as empty.
    That is, "external_network_bridge = ". The link between the network and
    the physical interface should be done via the provider network parameters.
    2. The plug operation for the linux bridge replaces the interface name
    prefix with tap. We need to ensure that the prefix length is 3 characters.

    Change-Id: Ib8e26bc1f603a1aff9560b4a40110a6824db5921