ovs_lib.OVSBridge mod_flow() method doesn't work

[Aleksandr Chirko]

During my OVS-related prototyping I spotted this. For bug verification I used 'ovs_lib' as a standalone python package (without Openstack runnig).

OVS info:
    ovs-ofctl (Open vSwitch) 1.4.0+build0
    Compiled Feb 18 2013 13:13:22
    OpenFlow versions 0x1:0x1

I can define flow with no problems:
    from neutron.agent.linux import ovs_lib

    int_br = ovs_lib.OVSBridge('br-int', root_helper='sudo')
    int_br.add_flow(priority=777,dl_type=2048, actions='normal')

Run 'ovs-ofctl dump-flows br-int'
    'cookie=0x0, duration=115.956s, table=0, n_packets=0, n_bytes=0, priority=777,ip actions=NORMAL'

However when I try to modify this flow:
    int_br.mod_flow(dl_type=2048, actions='drop')
I see
    'Command: ['sudo', 'ovs-ofctl', 'mod-flows', 'br-int', 'hard_timeout=0,idle_timeout=0,priority=0,dl_type=2048,actions=drop']
    Exit code: 1
    Stdout: ''
    Stderr: 'ovs-ofctl: unknown keyword hard_timeout\n'

[Eugene Nikanorov (enikanorov)]

What version of OVS are you using?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/58533

[Akihiro Motoki (amotoki)]

According to the output of ovs-ofctl (version and build date),
OVS version is 1.4.0 and it comes from Ubuntu 12.04 OVS package.

[Kyle Mestery (mestery)]

The actual problem here is that "hard_timeout" is not a supported argument when modifying an existing flow. The patch, as proposed, does address this, but it also introduces some significant changes to the flow programming logic. I am still reviewing those at the moment.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/58533
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=3c00dd43f613c838f713a7cbf3cedb6767a8c52a
Submitter: Jenkins
Branch: master

commit 3c00dd43f613c838f713a7cbf3cedb6767a8c52a
Author: Aleks Chirko <email address hidden>
Date: Tue Nov 26 16:22:57 2013 +0200

    Bugfix and refactoring for ovs_lib flow methods

    Remove hardcoded flow parameters from
    '_build_flow_expr_str' method, so we can
    define any flows we want and can rely on 'ovs-ofctl'
    command to verify flow arguments correctness.
    When building flow string inside _build_flow_expr_str
    use the following approach:
    1. Build prefix and remove prefix params from flow_dict.
    2. Build postfix (actions) and remove 'actions' from
    flow dict.
    3. Inside the loop build flow array from everything
    what's left in flow_dict.
    4. Append postfix (actions) to the flow array.
    5. 'Join' flow array into flow string.

    Change _build_flow_expr_str() to be a function
    instead of an object method because 'self'
    parameter wasn't used.

    Remove 'add_or_mod_flow_str' method because
    we have to use separate logic when bulding flow
    strings for 'add_flow' and 'mod_flow' methods.

    Add more unit tests for OVSBridge class.

    Closes-Bug: #1255058
    Closes-Bug: #1240572

    Change-Id: Ic89221d006a626aa2fc40314a9acffc0ea6fd61c