a NonVoter node should never try to bootstrap (#492)

This is a follow-up to #483

api.go

@@ -36,6 +36,10 @@ var (
 	// follower or candidate node.
 	ErrNotLeader = errors.New("node is not the leader")
 
+	// ErrNotVoter is returned when an operation can't be completed on a
+	// non-voter node.
+	ErrNotVoter = errors.New("node is not a voter")
+
 	// ErrLeadershipLost is returned when a leader fails to commit a log entry
 	// because it's been deposed in the process.
 	ErrLeadershipLost = errors.New("leadership lost while committing log")

raft.go

@@ -233,6 +233,11 @@ func (r *Raft) runFollower() {
 // the Raft object's member BootstrapCluster for more details. This must only be
 // called on the main thread, and only makes sense in the follower state.
 func (r *Raft) liveBootstrap(configuration Configuration) error {
+	if !hasVote(configuration, r.localID) {
+		// Reject this operation since we are not a voter
+		return ErrNotVoter
+	}
+
 	// Use the pre-init API to make the static updates.
 	cfg := r.config()
 	err := BootstrapCluster(&cfg, r.logs, r.stable, r.snapshots, r.trans, configuration)

raft_test.go

@@ -99,6 +99,31 @@ func TestRaft_LiveBootstrap(t *testing.T) {
 	}
 }
 
+func TestRaft_LiveBootstrap_From_NonVoter(t *testing.T) {
+	// Make the cluster.
+	c := MakeClusterNoBootstrap(2, t, nil)
+	defer c.Close()
+
+	// Build the configuration.
+	configuration := Configuration{}
+	for i, r := range c.rafts {
+		server := Server{
+			ID:      r.localID,
+			Address: r.localAddr,
+		}
+		if i == 0 {
+			server.Suffrage = Nonvoter
+		}
+		configuration.Servers = append(configuration.Servers, server)
+	}
+
+	// Bootstrap one of the nodes live (the non-voter).
+	boot := c.rafts[0].BootstrapCluster(configuration)
+	if err := boot.Error(); err != ErrNotVoter {
+		t.Fatalf("bootstrap should have failed: %v", err)
+	}
+}
+
 func TestRaft_RecoverCluster_NoState(t *testing.T) {
 	c := MakeClusterNoBootstrap(1, t, nil)
 	defer c.Close()