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

Christine Caulfield ccaulfie at redhat.com
Mon Jan 4 02:36:20 EST 2021

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 >= 

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.

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
	ipprefix: 24

See corosync.conf(5) for more information.


>> 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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