Kevin, Miguel,
I agree that (4) is what makes most sense.
(more below)
Miguel Angel Ajo :
Do you have a rough idea of what operations you may need to do?
Right now, what bagpipe driver for networking-bgpvpn needs to interact
with is:
- int_br OVSBridge (read-only)
- tun_br OVSBridge (add patch port, add flows)
- patch_int_ofport port number (read-only)
- local_vlan_map dict (read-only)
- setup_entry_for_arp_reply method (called to add static ARP entries)
Please bear in mind, the extension interface will be available from
different agent types
(OVS, SR-IOV, [eventually LB]), so this interface you're talking about
could also serve as
a translation driver for the agents (where the translation is
possible), I totally understand
that most extensions are specific agent bound, and we must be able to
identify
the agent we're serving back exactly.
Yes, I do have this in mind, but what we've identified for now seems to
be OVS specific.
-Thomas
Kevin Benton wrote:
I think the 4th of the options you proposed would be the best. We don't
want to give agents direct access to the agent object or else we will
run
the risk of breaking extensions all of the time during any kind of
reorganization or refactoring. Having a well defined API in between will
give us flexibility to move things around.
On Fri, Sep 25, 2015 at 1:32 AM,<thomas.mo...@orange.com> wrote:
Hi everyone,
(TL;DR: we would like an L2 agent extension to be able to call
methods on
the agent class, e.g. OVSAgent)
In the networking-bgpvpn project, we need the reference driver to
interact
with the ML2 openvswitch agent with new RPCs to allow exchanging
information with the BGP VPN implementation running on the compute
nodes.
We also need the OVS agent to setup specific things on the OVS
bridges for
MPLS traffic.
To extend the agent behavior, we currently create a new agent by
mimicking
the main() in ovs_neutron_agent.py but instead of instantiating
instantiate
OVSAgent, with instantiate a class that overloads the OVSAgent class
with
the additional behavior we need [1] .
This is really not the ideal way of extending the agent, and we would
prefer using the L2 agent extension framework [2].
Using the L2 agent extension framework would work, but only
partially: it
would easily allos us to register our RPC consumers, but not to let us
access to some datastructures/methods of the agent that we need to use:
setup_entry_for_arp_reply and local_vlan_map, access to the OVSBridge
objects to manipulate OVS ports.
I've filled-in an RFE bug to track this issue [5].
We would like something like one of the following:
1) augment the L2 agent extension interface
(AgentCoreResourceExtension)
to give access to the agent object (and thus let the extension call
methods
of the agent) by giving the agent as a parameter of the initialize
method
[4]
2) augment the L2 agent extension interface
(AgentCoreResourceExtension)
to give access to the agent object (and thus let the extension call
methods
of the agent) by giving the agent as a parameter of a new setAgent
method
3) augment the L2 agent extension interface
(AgentCoreResourceExtension)
to give access only to specific/chosen methods on the agent object, for
instance by giving a dict as a parameter of the initialize method [4],
whose keys would be method names, and values would be pointer to these
methods on the agent object
4) define a new interface with methods to access things inside the
agent,
this interface would be implemented by an object instantiated by the
agent,
and that the agent would pass to the extension manager, thus
allowing the
extension manager to passe the object to an extension through the
initialize method of AgentCoreResourceExtension [4]
Any feedback on these ideas...?
Of course any other idea is welcome...
For the sake of triggering reaction, the question could be rephrased
as:
if we submit a change doing (1) above, would it have a reasonable
chance of
merging ?
-Thomas
[1]
https://github.com/openstack/networking-bgpvpn/blob/master/networking_bgpvpn/neutron/services/service_drivers/bagpipe/ovs_agent/ovs_bagpipe_neutron_agent.py
[2] https://review.openstack.org/#/c/195439/
[3]
https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/extension_drivers/qos_driver.py#L30
[4]
https://github.com/openstack/neutron/blob/master/neutron/agent/l2/agent_extension.py#L28
[5] https://bugs.launchpad.net/neutron/+bug/1499637
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