[ovirt-devel] [proposal] deprecate VDSM ping in favor of ping2 and confirmConnectivity

[Edward Haas]

On Mon, Aug 7, 2017 at 11:06 PM, Nir Soffer <nsoffer at redhat.com> wrote:

> On Mon, Aug 7, 2017 at 5:28 PM Roy Golan <rgolan at 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 <phoracek at 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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