Implemented functionality to add voter to raft cluster upon leader receiving join request broadcast.

Servers broadcast join cluster message until they receive a message confirming they have successfully joined.

server/raft.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -114,6 +115,41 @@ func (server *Server) isRaftLeader() bool {
 	return server.raft.State() == raft.Leader
 }
 
+func (server *Server) addVoter(
+	id raft.ServerID,
+	address raft.ServerAddress,
+	prevIndex uint64,
+	timeout time.Duration,
+) error {
+	if server.isRaftLeader() {
+		raftConfig := server.raft.GetConfiguration()
+		if err := raftConfig.Error(); err != nil {
+			return errors.New("could not retrieve raft config")
+		}
+
+		for _, s := range raftConfig.Configuration().Servers {
+			// Check if a server already exists with the current attribtues
+			if s.ID == id && s.Address == address {
+				return fmt.Errorf("server with id %s and address %s already exists", id, address)
+			}
+		}
+
+		err := server.raft.AddVoter(id, address, prevIndex, timeout).Error()
+		if err != nil {
+			return err
+		}
+
+		// After successfully adding the voter node, broadcast the success message
+		msg := BroadcastMessage{
+			Action:     "RaftJoinSuccess",
+			ServerID:   id,
+			ServerAddr: address,
+		}
+		server.broadcastQueue.QueueBroadcast(&msg)
+	}
+	return nil
+}
+
 func (server *Server) RaftShutdown() {
 	// Triggered before MemberListShutdown
 	// Leadership transfer if current node is the leader