[ClusterLabs] Running shell command on remote node via corosync messaging infrastructure

[Klaus Wenninger]

On 1/4/21 8:36 AM, Christine Caulfield wrote:
>
>
> On 18/12/2020 20:41, Andrei Borzenkov wrote:
>> 18.12.2020 21:54, Ken Gaillot пишет:
>>> On Fri, 2020-12-18 at 17:51 +0000, Animesh Pande wrote:
>>>> Hello,
>>>>
>>>> Is there a tool that would allow for commands to be run on remote
>>>> nodes in the cluster through the corosync messaging layer? I have a
>>>> cluster configured with multiple corosync communication rings (public
>>>> network and private network). I would like to be able to run a
>>>> command on the remote node through corosync layer even when the
>>>> communication ring associated with the public network goes down but
>>>> the private network communication ring is still connected.
>>>>
>>>> Please let me know if there is such a tool provided by corosync that
>>>> I can use.
>>>>
>>>> Thank you for your time!
>>>>
>>>> Best regards,
>>>> Animesh
>>>
>>> Hi,
>>>
>>> No, there is not. I'm assuming you're using "remote" in the
>>> conventional sense and not for Pacemaker Remote nodes, but the answer
>>> is no either way. :)
>>>
>>> Of course, you can configure sshd to listen on the cluster interface.
>>
>> What do you call "cluster interface"? As I understand the question, the
>> idea is to use redundancy of corosync communication. Is it possible to
>> configure virtual interface on top of corosync rings?
>>
>
>
> Yes there is. It's called the 'nozzle' device and works in corosync >=
> 3.0.2.
>
> It creates a pseudo device that passes all traffic through the knet
> transport, so you get the redundancy of multiple links transparently.
> You don't get join/leave up/down notifications like CPG (because it's
> an interface not an API) but you can use the API if you need those.
Talking of this ... would it be possible / make sense to translate that
to something
that trigger if/link up/down somehow? (up as long as there is at least
one member
apart from the local node or something)

Klaus
>
> I'm not sure if it's supported in pcs yet, but you just add the
> information too corosync.conf (on all nodes):
>
> nozzle {
>     name: noz01
>     ipaddr 192.168.10.0
>     ipprefix: 24
> }
>
> See corosync.conf(5) for more information.
>
>
> Chrissie
>
>
>>> If you give the cluster interface on each node a unique name in DNS (or
>>> hosts or whatever), you can ssh to that name.
>>>
>>
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