Clarification about cluster changes when in minority

[visciang]

Hello!

I've been playing with a ra cluster of 3 nodes: A, B, C.
Cluster successfully established, with leader B.
I've shutdown the two followers A and C leaving the leader B alone.

At this point I've tried to change the cluster topology adding a new node D.
The node has been accepted by B, and D has a "follower" role.

Is this what we should expect, being in minority?

Then I've tried to add another node E.
In this case the operation is instead rejected with cause cluster_change_not_permitted.

Why?

Attaching here an example to reproduce the above steps (this has been tested with ra v2.6.3).

Thank you!
Giovanni

test.txt

[lessness]

Any news on this? Looks like a bug.

Federico

[kjnilsson]

If you have a leader you can always make one member change. The member changes take effect when adding the cluster change command to the log not on consensus as perhaps is what you expect. See the raft paper/thesis for more details.

Closing as expected behaviour.