Open Stack

On Wed, Jan 27, 2016 at 4:52 PM, Sean M. Collins <sean at coreitpro.com> wrote:
> On Wed, Jan 27, 2016 at 04:24:00PM EST, Assaf Muller wrote:
>> On Wed, Jan 27, 2016 at 4:10 PM, Sean M. Collins <sean at coreitpro.com> wrote:
>> > Hi,
>> >
>> > I started poking a bit at https://bugs.launchpad.net/devstack/+bug/1535661
>> >
>> > We have radvd processes that the l3 agent launches, and if the l3 agent
>> > is terminated these radvd processes continue to run. I think we should
>> > probably terminate them when the l3 agent is terminated, like if we are
>> > in DevStack and doing an unstack.sh[1]. There's a fix on the DevStack
>> > side but I'm waffling a bit on if it's the right thing to do or not[2].
>> >
>> > The only concern I have is if there are situations where the l3 agent
>> > terminates, but we don't want data plane disruption. For example, if
>> > something goes wrong and the L3 agent dies, if the OS will be sending a
>> > SIGABRT (which my WIP patch doesn't catch[3] and radvd would continue to run) or if a
>> > SIGTERM is issued, or worse, an OOM event occurs (I think thats a
>> > SIGTERM too?) and you get an outage.
>>
>> RDO systemd init script for the L3 agent will send a signal 15 when
>> 'systemctl restart neutron-l3-agent' is executed. I assume
>> Debian/Ubuntu do the same. It is imperative that agent restarts do not
>> cause data plane interruption. This has been the case for the L3 agent
>
> But wouldn't it really be wiser to use SIGHUP to communicate the intent
> to restart a process?

Maybe. I just checked and on a Liberty based RDO installation, sending
SIGHUP to a L3 agent doesn't actually do anything. Specifically it
doesn't resync its routers (Which restarting it with signal 15 does).

>
> --
> Sean M. Collins
>
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