Why isn't the stomp heartbeat enough?

On Tue, 8 Aug 2017 at 13:45 Martin Sivak <msi...@redhat.com> wrote:

> MOM and hosted engine use the ping verb to verify the connection is
> still OK. The RPC client did not have any reconnect logic in the past
> (and I think it still does not..).
>
> Martin
>
> On Tue, Aug 8, 2017 at 12:01 PM, Roy Golan <rgo...@redhat.com> wrote:
> > Petr, why do you need the ping verb? what are you after?
> >
> > On Tue, 8 Aug 2017 at 11:54 Martin Sivak <msi...@redhat.com> wrote:
> >>
> >> > The proposed solution is focused on making sure a command does one
> thing
> >> > and
> >> > not two:
> >> > A ping that has no side effects and a "watchdog" mechanism to confirm
> >> > connectivity.
> >>
> >> This sounds as exactly the right solution right now.
> >>
> >> >>> Still someone could call conirmConnectivity, no?
> >>
> >> We do not protect any other endpoints that can cause the host to go
> >> wild (storage or even setupNetworks). I agree with Edward it is the
> >> responsibility of the caller to do the right thing. You need to be
> >> root or have the certificate to talk to VDSM anyway.
> >>
> >> Martin
> >>
> >> On Tue, Aug 8, 2017 at 8:24 AM, Edward Haas <eh...@redhat.com> wrote:
> >> >
> >> >
> >> > On Mon, Aug 7, 2017 at 11:06 PM, Nir Soffer <nsof...@redhat.com>
> wrote:
> >> >>
> >> >> On Mon, Aug 7, 2017 at 5:28 PM Roy Golan <rgo...@redhat.com> wrote:
> >> >>>
> >> >>> Still someone could call conirmConnectivity, no? so the state isn't
> >> >>> guarded from localhost tinkering anyhow. If you really need a
> solution
> >> >>> you
> >> >>> can acuire a token for this operation by setupNetworks, and confirm
> >> >>> connectivity with this token passed back.
> >> >>>
> >> >>> I'm not sure about the severity of the problem here, I'll let other
> >> >>> reply, but I'm against this kind of solution.
> >> >>>
> >> >>>
> >> >>>
> >> >>> On Mon, 7 Aug 2017 at 15:32 Petr Horacek <phora...@redhat.com>
> wrote:
> >> >>>>
> >> >>>> Hello,
> >> >>>>
> >> >>>> current VDSM ping verb has a problem - it confirms network
> >> >>>> connectivity as a side-effect. After Engine calls setupNetwork it
> >> >>>> pings VDSM host to confirm that external network connectivity is
> not
> >> >>>> broken. This prohibits other users to call ping from localhost
> since
> >> >>>> it would confirm connectivity even though networking could be
> broken.
> >> >>
> >> >>
> >> >> Vdsm can save the client ip setting up the network. Getting a ping
> from
> >> >> this
> >> >> client can confirm that the connectivity was restored. pings from
> other
> >> >> hosts
> >> >> can be ignored.
> >> >>
> >> >> The client address is available in a thread local variable
> >> >> (context.client_host)
> >> >> during all api calls. see vdsm.common.api.context_string() for
> example
> >> >> usage.
> >> >>
> >> >> This infrastructure is available in 4.1.
> >> >
> >> >
> >> > The proposed solution is focused on making sure a command does one
> thing
> >> > and
> >> > not two:
> >> > A ping that has no side effects and a "watchdog" mechanism to confirm
> >> > connectivity.
> >> >
> >> > Does it make sense to confirm connectivity from localhost? In many
> cases
> >> > it
> >> > probably does not,
> >> > but there may be cases where it does make sense... it is not the
> >> > functionality to determine what
> >> > makes sense or not, it is the usage of it who has the responsibility
> to
> >> > use
> >> > it correctly.
> >> >
> >> >>
> >> >> Nir
> >> >>
> >> >>>>
> >> >>>>
> >> >>>> In order to fix this problem ping should be split to ping2 (which
> >> >>>> just
> >> >>>> returns Success with no side-effect) and confirmConnectivity.
> Change
> >> >>>> on VDSM side was introduced in [1], we still need to expose new
> verbs
> >> >>>> in Engine.
> >> >>>>
> >> >>>> Regards,
> >> >>>> Petr
> >> >>>>
> >> >>>> [1] https://gerrit.ovirt.org/#/c/80119/
> >> >>>> _______________________________________________
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> >> >>>
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> >> >>
> >> >>
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> >> >
> >> >
> >> >
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