raft.cluster was throwing an error when there was no leader in the network. Fixed the same.

added nodeActive attribute to the api response which indicates if the node is active in raft cluster.
added error handling for other apis

raft/api.go

@@ -1,5 +1,10 @@
 package raft
 
+import (
+	"errors"
+	"github.com/coreos/etcd/pkg/types"
+)
+
 type RaftNodeInfo struct {
 	ClusterSize    int        `json:"clusterSize"`
 	Role           string     `json:"role"`
@@ -19,22 +24,49 @@ func NewPublicRaftAPI(raftService *RaftService) *PublicRaftAPI {
 }
 
 func (s *PublicRaftAPI) Role() string {
+	if err := s.checkIfNodeInCluster(); err != nil {
+		return ""
+	}
+	_, err := s.raftService.raftProtocolManager.LeaderAddress()
+	if err != nil {
+		return ""
+	}
 	return s.raftService.raftProtocolManager.NodeInfo().Role
 }
 
+// helper function to check if self node is part of cluster
+func (s *PublicRaftAPI) checkIfNodeInCluster() error {
+	if s.raftService.raftProtocolManager.IsIDRemoved(uint64(s.raftService.raftProtocolManager.raftId)) {
+		return errors.New("node not part of raft cluster. operations not allowed")
+	}
+	return nil
+}
+
 func (s *PublicRaftAPI) AddPeer(enodeId string) (uint16, error) {
+	if err := s.checkIfNodeInCluster(); err != nil {
+		return 0, err
+	}
 	return s.raftService.raftProtocolManager.ProposeNewPeer(enodeId, false)
 }
 
 func (s *PublicRaftAPI) AddLearner(enodeId string) (uint16, error) {
+	if err := s.checkIfNodeInCluster(); err != nil {
+		return 0, err
+	}
 	return s.raftService.raftProtocolManager.ProposeNewPeer(enodeId, true)
 }
 
 func (s *PublicRaftAPI) PromoteToPeer(raftId uint16) (bool, error) {
+	if err := s.checkIfNodeInCluster(); err != nil {
+		return false, err
+	}
 	return s.raftService.raftProtocolManager.PromoteToPeer(raftId)
 }
 
 func (s *PublicRaftAPI) RemovePeer(raftId uint16) error {
+	if err := s.checkIfNodeInCluster(); err != nil {
+		return err
+	}
 	return s.raftService.raftProtocolManager.ProposePeerRemoval(raftId)
 }
 
@@ -48,21 +80,31 @@ func (s *PublicRaftAPI) Leader() (string, error) {
 }
 
 func (s *PublicRaftAPI) Cluster() ([]ClusterInfo, error) {
+	// check if the node has already been removed from cluster
+	// if yes return nil
+	if err := s.checkIfNodeInCluster(); err != nil {
+		return []ClusterInfo{}, nil
+	}
+
 	nodeInfo := s.raftService.raftProtocolManager.NodeInfo()
 	if nodeInfo.Role == "" {
 		return []ClusterInfo{}, nil
 	}
+
+	noLeader := false
 	leaderAddr, err := s.raftService.raftProtocolManager.LeaderAddress()
 	if err != nil {
-		if err == errNoLeaderElected && s.Role() == "" {
+		noLeader = true
+		if s.raftService.raftProtocolManager.NodeInfo().Role == "" {
 			return []ClusterInfo{}, nil
 		}
-		return []ClusterInfo{}, err
 	}
+
 	peerAddresses := append(nodeInfo.PeerAddresses, nodeInfo.Address)
 	clustInfo := make([]ClusterInfo, len(peerAddresses))
 	for i, a := range peerAddresses {
 		role := ""
+		if !noLeader {
 			if a.RaftId == leaderAddr.RaftId {
 				role = "minter"
 			} else if s.raftService.raftProtocolManager.isLearner(a.RaftId) {
@@ -70,11 +112,25 @@ func (s *PublicRaftAPI) Cluster() ([]ClusterInfo, error) {
 			} else if s.raftService.raftProtocolManager.isVerifier(a.RaftId) {
 				role = "verifier"
 			}
-		clustInfo[i] = ClusterInfo{*a, role}
+		}
+		clustInfo[i] = ClusterInfo{*a, role, s.checkIfNodeIsActive(a.RaftId)}
 	}
 	return clustInfo, nil
 }
 
+// helper function to check of the raft node is active
+// of the raftnode is active ActiveSince returns non-zero time
+func (s *PublicRaftAPI) checkIfNodeIsActive(raftId uint16) bool {
+	if raftId == s.raftService.raftProtocolManager.raftId {
+		return true
+	}
+	activeSince := s.raftService.raftProtocolManager.transport.ActiveSince(types.ID(raftId))
+	if activeSince.IsZero() {
+		return false
+	}
+	return true
+}
+
 func (s *PublicRaftAPI) GetRaftId(enodeId string) (uint16, error) {
 	return s.raftService.raftProtocolManager.FetchRaftId(enodeId)
 }

raft/peer.go

@@ -30,6 +30,7 @@ type Address struct {
 type ClusterInfo struct {
 	Address
 	Role       string `json:"role"`
+	NodeActive bool   `json:"nodeActive"`
 }
 
 func newAddress(raftId uint16, raftPort int, node *enode.Node, withHostname bool) *Address {