dynamic node list

[benoitc]

Is there a way to add dynamically a nodes to the list of potential leaders?

[archaelus]

Right now? No.

The Async Bully algorithm given by Stoller doesn't contain any mechanism for updating the set of peers and quite a bit of the algorithm seems dependent on the set being identical on all nodes. However, operationally it's a pain not to have this capability, so I'll have a think about it.

Currently messages are tagged with the election_id, gl_async_bully name and a few other things to make sure that only processes with the right configuration participate in the protocol. Perhaps we could add a checksum over the whole configuration (service name, peer set, election_id) to the messages instead which will prevent differently configured nodes from interfering with eachother. We could then add a broadcast message from the leader to change the configuration. At worst, if the update message gets lost, then some nodes will form effectively disconnected subsets (and elect their own leaders), but different subsets won't interfere with each other as they'll ignore eachother's messages.

Anyone else have ideas on how to solve this?