Batch logs output to speedup minikube logs command

pkg/minikube/logs/logs.go

@@ -184,10 +184,12 @@ func Output(r cruntime.Manager, bs bootstrapper.Bootstrapper, cfg config.Cluster
 			failed = append(failed, name)
 			continue
 		}
+		l := ""
 		scanner := bufio.NewScanner(&b)
 		for scanner.Scan() {
-			out.Styled(style.Empty, scanner.Text())
+			l += scanner.Text() + "\n"
 		}
+		out.Styled(style.Empty, l)
 	}
 
 	if len(failed) > 0 {
@@ -223,10 +225,12 @@ func outputLastStart() error {
 		return fmt.Errorf("failed to open file %s: %v", fp, err)
 	}
 	defer f.Close()
+	l := ""
 	s := bufio.NewScanner(f)
 	for s.Scan() {
-		out.Styled(style.Empty, s.Text())
+		l += s.Text() + "\n"
 	}
+	out.Styled(style.Empty, l)
 	if err := s.Err(); err != nil {
 		return fmt.Errorf("failed to read file %s: %v", fp, err)
 	}

test/integration/aaa_download_only_test.go

@@ -158,6 +158,19 @@ func TestDownloadOnly(t *testing.T) {
 				}
 			})
 
+			// checks if the duration of `minikube logs` takes longer than 5 seconds
+			t.Run("LogsDuration", func(t *testing.T) {
+				ctx, cancel := context.WithTimeout(context.Background(), Seconds(5))
+				defer cancel()
+				args := []string{"logs", "-p", profile}
+				if _, err := Run(t, exec.CommandContext(ctx, Target(), args...)); err != nil {
+					t.Logf("minikube logs failed with error: %v", err)
+				}
+				if err := ctx.Err(); err == context.DeadlineExceeded {
+					t.Error("minikube logs expected to finish by 5 seconds, but took longer")
+				}
+			})
+
 		})
 	}