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Hi Vijay,

Currently you may follow two ways in writing an LBaaS driver:
1) write it from scratch (like Radware, Netscaler, Embrane drivers) -
    in this case your driver should inherit
abstract_driver.LoadBalancerAbstractDriver
and
    will be running on Neutron service process, LBaaS agent won't be used.
    So you should restart not q-lbaas but q-svc process in order for new
driver to be used and it should work with the steps you've described.

2) leverage
neutron/services/loadbalancer/drivers/common/agent_drive_base.py framework
and in fact write only device driver which inheritits

neutron.services.loadbalancer.agent.agent_device_driver.AgentDeviceDriver.
    This is how HAProxy driver is implemented, please see
neutron/services/loadbalancer/drivers/haproxy/plugin_driver.py
    and namespace_driver.py (this is device driver).
    Along with updating service_provider in neutron.conf you should also
add your device driver to lbaas_agent.ini file (again please check how it
is done for haproxy)
    In this case your driver will be running on LBaaS agent and you should
restart both q-svc and q-lbaas.

Generally, the second approach is preferable as it's better scalable and
provides you a built-in async mechanism.

Thanks,
Oleg


On Wed, Apr 2, 2014 at 5:44 AM, Vijay B <os.vbvs at gmail.com> wrote:

> Hi,
>
>
> I'm trying to understand how LBaaS drivers work and so am attempting to
> write a dummy driver that does nothing for now, but instead of loading my
> dummy driver, neutron always loads the HAProxy namespace driver. These are
> the steps I followed:
>
>
> 1) I created a new directory neutron/services/loadbalancer/drivers/dummy/,
> and in that directory I put in a new file dummy_driver.py, which
> basically has a class class
> DummyPluginDriver(abstract_driver.LoadBalancerAbstractDriver):
>
> and has empty __init__(), create_vip(), delete_vip() etc functions.
>
>
> 2) I'm testing using a devstack setup, so I also edited the
> /etc/neutron/neutron.conf file, commenting out the default loadbalancer
> driver entry for HAProxy, and added a line for my dummy driver as follows:
>
>
>
> service_provider=LOADBALANCER:Dummy:neutron.services.loadbalancer.drivers.dummy.dummy_driver.DummyPluginDriver:default
>
>
>
> 3) I created a /etc/neutron/services/loadbalancer/dummy/lbaas_agent.ini
> directory/file
>
> I simply copied over the haproxy's lbaas_agent.ini file and changed
> [haproxy] to [dummy]
>
> and then I restarted the q-lbaas service using cd /opt/stack/neutron &&
> python /usr/local/bin/neutron-lbaas-agent --config-file
> /etc/neutron/neutron.conf
> --config-file=/etc/neutron/services/loadbalancer/dummy/lbaas_agent.ini
>
>
>
> However, I see that the default HAProxyNS driver is still being loaded
>
> When I put a breakpoint in loadbalancer/agent/agent_manager.py:86, I see
> this (relevant text marked in red):
>
>
>
> 2014-03-31 13:47:16.998 DEBUG neutron.common.utils [-] Reloading cached
> file /etc/neutron/policy.json from (pid=28405) read_cached_file
> /opt/stack/neutron/neutron/common/utils.py:53
>
> 2014-03-31 13:47:16.998 DEBUG neutron.policy [-] Loading policies from
> file: /etc/neutron/policy.json from (pid=28405) _set_rules
> /opt/stack/neutron/neutron/policy.py:89
>
> >
> /opt/stack/neutron/neutron/services/loadbalancer/agent/agent_manager.py(86)_load_drivers()
>
> -> self.device_drivers = {}
>
> (Pdb) l
>
>  81             # pool_id->device_driver_name mapping used to store known
> instances
>
>  82             self.instance_mapping = {}
>
>  83
>
>  84         def _load_drivers(self):
>
>  85             import pdb; pdb.set_trace()
>
>  86  ->         self.device_drivers = {}
>
>  87             for driver in self.conf.device_driver:
>
>  88                 try:
>
>  89                     driver_inst = importutils.import_object(
>
>  90                         driver,
>
>  91                         self.conf,
>
> (Pdb) self.conf.device_driver
>
>
> ['neutron.services.loadbalancer.drivers.haproxy.namespace_driver.HaproxyNSDriver']
>
> (Pdb)
>
>
> I'm not sure what I'm doing wrong - am I missing something that needs to
> be done within the dummy driver itself? (in dummy_driver.py?). Should I
> register some opts or similar?
>
>
> Any help would be much appreciated!
>
>
>
> Thanks,
>
> Regards,
>
> Vijay
>
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> OpenStack-dev at lists.openstack.org
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>
>
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