Follower rejecting leader's pre-vote #606
Description
Hello, thanks for the library! We were trying out raft v1.7.0, and found that the pre-vote implementation has a bug where a follower rejects the pre-vote req from node X even when when the follower thinks that X is the leader.
This is the offending line. https://github.com/hashicorp/raft/blob/main/raft.go#L1752
// Check if we have an existing leader [who's not the candidate] and also
var candidate ServerAddress // ISSUE: this is not set at all
candidateID := ServerID(req.ID)
// if the Servers list is empty that mean the cluster is very likely trying to bootstrap,
// Grant the vote
if len(r.configurations.latest.Servers) > 0 && !inConfiguration(r.configurations.latest, candidateID) {
r.logger.Warn("rejecting pre-vote request since node is not in configuration",
"from", candidate)
return
}
if leaderAddr, leaderID := r.LeaderWithID(); leaderAddr != "" && leaderAddr != candidate { // ISSUE: so this will always return true as long as the follower has a leader
r.logger.Warn("rejecting pre-vote request since we have a leader",
"from", candidate,
"leader", leaderAddr,
"leader-id", string(leaderID))
return
}