[nEdge] Implement clustering and high-availability

[lucaderi]

As nEdge is used inline, a fault can disrupt the whole network. It is requested to implement a way to federate instances in order to implement high-availability so that

• traffic is distributed across available nEdge instances
• in case of fault of an instance, the other nEdge instance will handle the load

[lucaderi]

A possible implementation option is to implement hot-standby

[sciolto]

We have an actual use case for a customer project. They happily use nEdge as traffic shaper, but need to make it high-available in a cluster.

[cory-usap]

I am working on setting up a HA cluster between two linux instances. Instead of opening up a new thread this seems to fit in this thread.

I have requested a Quota persist feature for nEdge ion #8882

However since this could be some time before it is updated I was wondering if theres a way to sync this to a hot-standby secondary server using corosync+pacemaker [1]?

I understand that it's not persisted however maybe there is a way to sync this over into the running application then we could sync it back when the primary comes back and takes over the HA cluster.

[1] https://www.habibza.in/configuration-ha-cluster-corosync-and-pacemaker-ubuntu-20-04/