You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure()

django-celery执行celery -A my_celery.tasks worker -l info报错：
django.core.exceptions.ImproperlyConfigured: Requested setting INSTALLED_APPS, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

或者 ： Model class django.contrib.contenttypes.models.ContentType doesn’t declare an explicit app_label and isn’t in an application in INSTALLED_APPS

要看看导入的问题：导入app就会报错，这个文件夹中不能导入app