This changes our behaviors for streams and peer removals in several ways.

First we no longer try to auto-remap stream assignments on peer removals from the system.
We also now can always respond to stream info requests if at least a member is running.

Signed-off-by: Derek Collison <derek@nats.io>

server/jetstream_api.go

@@ -1532,14 +1532,10 @@ func (s *Server) jsStreamInfoRequest(sub *subscription, c *client, subject, repl
 		}
 
 		// Check to see if we are a member of the group and if the group has no leader.
-		if js.isGroupLeaderless(sa.Group) {
-			resp.Error = jsClusterNotAvailErr
-			s.sendAPIErrResponse(ci, acc, subject, reply, string(msg), s.jsonResponse(&resp))
-			return
-		}
+		isLeaderless := js.isGroupLeaderless(sa.Group)
 
 		// We have the stream assigned and a leader, so only the stream leader should answer.
-		if !acc.JetStreamIsStreamLeader(streamName) {
+		if !acc.JetStreamIsStreamLeader(streamName) && !isLeaderless {
 			if js.isLeaderless() {
 				resp.Error = jsClusterNotAvailErr
 				s.sendAPIErrResponse(ci, acc, subject, reply, string(msg), s.jsonResponse(&resp))
@@ -1839,12 +1835,6 @@ func (s *Server) jsStreamRemovePeerRequest(sub *subscription, c *client, subject
 	}
 
 	// Check to see if we are a member of the group and if the group has no leader.
-	if js.isGroupLeaderless(sa.Group) {
-		resp.Error = jsClusterNotAvailErr
-		s.sendAPIErrResponse(ci, acc, subject, reply, string(msg), s.jsonResponse(&resp))
-		return
-	}
-
 	// Peers here is a server name, convert to node name.
 	nodeName := string(getHash(req.Peer))
 

server/jetstream_cluster.go

@@ -977,11 +977,6 @@ func (js *jetStream) processRemovePeer(peer string) {
 	js.mu.Lock()
 	s, cc := js.srv, js.cluster
 
-	// Only leader will do remappings for streams and consumers.
-	if cc.isLeader() {
-		js.remapStreamsLocked(peer)
-	}
-
 	// All nodes will check if this is them.
 	isUs := cc.meta.ID() == peer
 	disabled := js.disabled
@@ -4252,6 +4247,12 @@ func (js *jetStream) clusterInfo(rg *raftGroup) *ClusterInfo {
 	now := time.Now()
 
 	id, peers := n.ID(), n.Peers()
+
+	// If we are leaderless, do not suppress putting us in the peer list.
+	if ci.Leader == _EMPTY_ {
+		id = _EMPTY_
+	}
+
 	for _, rp := range peers {
 		if rp.ID != id && rg.isMember(rp.ID) {
 			lastSeen := now.Sub(rp.Last)
@@ -4271,9 +4272,15 @@ func (js *jetStream) clusterInfo(rg *raftGroup) *ClusterInfo {
 
 func (mset *stream) handleClusterStreamInfoRequest(sub *subscription, c *client, subject, reply string, msg []byte) {
 	mset.mu.RLock()
-	sysc, js, config := mset.sysc, mset.srv.js, mset.cfg
+	sysc, js, sa, config := mset.sysc, mset.srv.js, mset.sa, mset.cfg
 	mset.mu.RUnlock()
 
+	// By design all members will receive this. Normally we only want the leader answering.
+	// But if we have stalled and lost quorom all can respond.
+	if sa != nil && !js.isGroupLeaderless(sa.Group) && !mset.isLeader() {
+		return
+	}
+
 	si := &StreamInfo{
 		Created: mset.createdTime(),
 		State:   mset.state(),

server/jetstream_cluster_test.go

@@ -3129,11 +3129,6 @@ func TestJetStreamClusterNoQuorumStepdown(t *testing.T) {
 		return err != nil && strings.Contains(err.Error(), "unavailable")
 	}
 
-	// Expect to get errors here.
-	if _, err := js.StreamInfo("NO-Q"); !notAvailableErr(err) {
-		t.Fatalf("Expected an 'unavailable' error, got %v", err)
-	}
-
 	checkFor(t, 2*time.Second, 100*time.Millisecond, func() error {
 		if cl := c.consumerLeader("$G", "NO-Q", ci.Name); cl == nil {
 			return nil
@@ -3166,9 +3161,6 @@ func TestJetStreamClusterNoQuorumStepdown(t *testing.T) {
 	if err := js.DeleteStream("NO-Q"); !notAvailableErr(err) {
 		t.Fatalf("Expected an 'unavailable' error, got %v", err)
 	}
-	if _, err := js.StreamInfo("NO-Q"); !notAvailableErr(err) {
-		t.Fatalf("Expected an 'unavailable' error, got %v", err)
-	}
 	if err := js.PurgeStream("NO-Q"); !notAvailableErr(err) {
 		t.Fatalf("Expected an 'unavailable' error, got %v", err)
 	}

server/stream.go

@@ -399,9 +399,18 @@ func (mset *stream) setStreamAssignment(sa *streamAssignment) {
 	mset.mu.Lock()
 	defer mset.mu.Unlock()
 	mset.sa = sa
+	if sa == nil {
+		return
+	}
+
 	// Set our node.
-	if sa != nil {
-		mset.node = sa.Group.node
+	mset.node = sa.Group.node
+
+	// Setup our info sub here as well for all stream members. This is now by design.
+	if mset.infoSub == nil {
+		isubj := fmt.Sprintf(clusterStreamInfoT, mset.jsa.acc(), mset.cfg.Name)
+		// Note below the way we subscribe here is so that we can send requests to ourselves.
+		mset.infoSub, _ = mset.srv.systemSubscribe(isubj, _EMPTY_, false, mset.sysc, mset.handleClusterStreamInfoRequest)
 	}
 }
 
@@ -438,13 +447,6 @@ func (mset *stream) setLeader(isLeader bool) error {
 
 // Lock should be held.
 func (mset *stream) startClusterSubs() {
-	if mset.infoSub == nil {
-		if jsa := mset.jsa; jsa != nil {
-			isubj := fmt.Sprintf(clusterStreamInfoT, jsa.acc(), mset.cfg.Name)
-			// Note below the way we subscribe here is so that we can send requests to ourselves.
-			mset.infoSub, _ = mset.srv.systemSubscribe(isubj, _EMPTY_, false, mset.sysc, mset.handleClusterStreamInfoRequest)
-		}
-	}
 	if mset.isClustered() && mset.syncSub == nil {
 		mset.syncSub, _ = mset.srv.systemSubscribe(mset.sa.Sync, _EMPTY_, false, mset.sysc, mset.handleClusterSyncRequest)
 	}
@@ -452,10 +454,6 @@ func (mset *stream) startClusterSubs() {
 
 // Lock should be held.
 func (mset *stream) stopClusterSubs() {
-	if mset.infoSub != nil {
-		mset.srv.sysUnsubscribe(mset.infoSub)
-		mset.infoSub = nil
-	}
 	if mset.syncSub != nil {
 		mset.srv.sysUnsubscribe(mset.syncSub)
 		mset.syncSub = nil
@@ -2524,6 +2522,12 @@ func (mset *stream) stop(deleteFlag, advisory bool) error {
 	// Unsubscribe from direct stream.
 	mset.unsubscribeToStream()
 
+	// Our info sub if we spun it up.
+	if mset.infoSub != nil {
+		mset.srv.sysUnsubscribe(mset.infoSub)
+		mset.infoSub = nil
+	}
+
 	// Quit channel.
 	if mset.qch != nil {
 		close(mset.qch)