simplify logic to check for vault read event

defer shutdown to cleanup after failed run

Co-Authored-By: Michael Schurter <mschurter@hashicorp.com>

update comment to include ctx note for shutdown

client/allocrunner/interfaces/task_lifecycle.go

@@ -89,7 +89,7 @@ type TaskPrestartHook interface {
 	// Prestart is called before the task is started including after every
 	// restart. Prestart is not called if the allocation is terminal.
 	//
-	// The context is cancelled if the task is killed.
+	// The context is cancelled if the task is killed or shutdown.
 	Prestart(context.Context, *TaskPrestartRequest, *TaskPrestartResponse) error
 }
 

client/allocrunner/taskrunner/task_runner_test.go

@@ -1766,6 +1766,7 @@ func TestTaskRunner_Template_BlockingPreStart(t *testing.T) {
 	tr, err := NewTaskRunner(conf)
 	require.NoError(t, err)
 	go tr.Run()
+	defer tr.Shutdown()
 
 	testutil.WaitForResult(func() (bool, error) {
 		ts := tr.TaskState()
@@ -1774,18 +1775,14 @@ func TestTaskRunner_Template_BlockingPreStart(t *testing.T) {
 			return false, fmt.Errorf("no events yet")
 		}
 
-		foundMissingVaultSecretEvent := false
 		for _, e := range ts.Events {
 			if e.Type == "Template" && strings.Contains(e.DisplayMessage, "vault.read(foo/secret)") {
-				foundMissingVaultSecretEvent = true
-			}
-		}
-
-		if !foundMissingVaultSecretEvent {
-			return false, fmt.Errorf("no missing vault secret template event yet: %#v", ts.Events)
-		}
-
 				return true, nil
+			}
+		}
+
+		return false, fmt.Errorf("no missing vault secret template event yet: %#v", ts.Events)
+
 	}, func(err error) {
 		require.NoError(t, err)
 	})