Improve gateway reliability and dashboard docs

clients/go/cmd/mxgw-go/main.go

@@ -377,17 +377,19 @@ func runSmoke(ctx context.Context, args []string, stdout, stderr io.Writer) erro
 	if err != nil {
 		return err
 	}
-	defer session.Close(context.Background())
 
 	serverHandle, err := session.Register(ctx, *clientName)
 	if err != nil {
-		return err
+		return closeSmokeSession(ctx, session, err)
 	}
 	itemHandle, err := session.AddItem(ctx, serverHandle, *item)
 	if err != nil {
-		return err
+		return closeSmokeSession(ctx, session, err)
 	}
 	if err := session.Advise(ctx, serverHandle, itemHandle); err != nil {
+		return closeSmokeSession(ctx, session, err)
+	}
+	if err := closeSmokeSession(ctx, session, nil); err != nil {
 		return err
 	}
 
@@ -406,6 +408,24 @@ func runSmoke(ctx context.Context, args []string, stdout, stderr io.Writer) erro
 	return nil
 }
 
+func closeSmokeSession(ctx context.Context, session *mxgateway.Session, primaryErr error) error {
+	closeCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	if deadline, ok := ctx.Deadline(); ok {
+		if until := time.Until(deadline); until > 0 && until < 5*time.Second {
+			cancel()
+			closeCtx, cancel = context.WithTimeout(context.Background(), until)
+			defer cancel()
+		}
+	}
+
+	_, closeErr := session.Close(closeCtx)
+	if primaryErr != nil {
+		return primaryErr
+	}
+	return closeErr
+}
+
 func bindCommonFlags(flags *flag.FlagSet) *commonOptions {
 	common := &commonOptions{}
 	flags.StringVar(&common.Endpoint, "endpoint", "localhost:5000", "gateway endpoint")