fix #1732

Signed-off-by: monkey <[email protected]>

Author: monkey92t

sentinel.go

@@ -219,14 +219,21 @@ func masterSlaveDialer(
 				failover.trySwitchMaster(ctx, addr)
 			}
 		}
-
 		if err != nil {
 			return nil, err
 		}
 		if failover.opt.Dialer != nil {
 			return failover.opt.Dialer(ctx, network, addr)
 		}
-		return net.DialTimeout("tcp", addr, failover.opt.DialTimeout)
+
+		netDialer := &net.Dialer{
+			Timeout:   failover.opt.DialTimeout,
+			KeepAlive: 5 * time.Minute,
+		}
+		if failover.opt.TLSConfig == nil {
+			return netDialer.DialContext(ctx, network, addr)
+		}
+		return tls.DialWithDialer(netDialer, network, addr, failover.opt.TLSConfig)
 	}
 }