问题：

芹菜容器在使用django cache_页面时崩溃（InvalidCacheBackendError）

林鸿彩

2023-03-14

我的Django webapp项目面临一个问题。我正在运行一个使用Django、Postgres、Redis和芹菜的集装箱化环境。主要是，我想使用Redis缓存和芹菜设置实时更新。到目前为止，我已经能够连接到redis和芹菜，并将芹菜任务结果存储在redis缓存中。当我试图使用Redis在django中缓存页面时，事情变得一团糟。出于某种原因，使用django的缓存系统（cache\u pagedecorator）会破坏我的芹菜容器。

错误

我的芹菜容器遇到以下错误：

django.core.cache.backends.base.InvalidCacheBackendError：找不到后端django_redis.cache.RedisCache：没有名为django_redis的模块

以下是完整的回溯：

Traceback (most recent call last):

File "/usr/local/lib/python3.9/site-packages/django/core/cache/__init__.py", line 50, in _create_cache

backend_cls = import_string(backend)

File "/usr/local/lib/python3.9/site-packages/django/utils/module_loading.py", line 17, in import_string

module = import_module(module_path)

File "/usr/local/lib/python3.9/importlib/__init__.py", line 127, in import_module

return _bootstrap._gcd_import(name[level:], package, level)

File "<frozen importlib._bootstrap>", line 1030, in _gcd_import

File "<frozen importlib._bootstrap>", line 1007, in _find_and_load

File "<frozen importlib._bootstrap>", line 972, in _find_and_load_unlocked

File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed

File "<frozen importlib._bootstrap>", line 1030, in _gcd_import

File "<frozen importlib._bootstrap>", line 1007, in _find_and_load

File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked

ModuleNotFoundError: No module named 'django_redis'


During handling of the above exception, another exception occurred:


Traceback (most recent call last):

File "/usr/local/bin/celery", line 8, in <module>

sys.exit(main())

File "/usr/local/lib/python3.9/site-packages/celery/__main__.py", line 15, in main

sys.exit(_main())

File "/usr/local/lib/python3.9/site-packages/celery/bin/celery.py", line 213, in main

return celery(auto_envvar_prefix="CELERY")

File "/usr/local/lib/python3.9/site-packages/click/core.py", line 829, in __call__

return self.main(*args, **kwargs)

File "/usr/local/lib/python3.9/site-packages/click/core.py", line 782, in main

rv = self.invoke(ctx)

File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1259, in invoke

return _process_result(sub_ctx.command.invoke(sub_ctx))

File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1066, in invoke

return ctx.invoke(self.callback, **ctx.params)

File "/usr/local/lib/python3.9/site-packages/click/core.py", line 610, in invoke

return callback(*args, **kwargs)

File "/usr/local/lib/python3.9/site-packages/click/decorators.py", line 21, in new_func

return f(get_current_context(), *args, **kwargs)

File "/usr/local/lib/python3.9/site-packages/celery/bin/base.py", line 132, in caller

return f(ctx, *args, **kwargs)

File "/usr/local/lib/python3.9/site-packages/celery/bin/worker.py", line 320, in worker

worker = app.Worker(

File "/usr/local/lib/python3.9/site-packages/celery/worker/worker.py", line 94, in __init__

self.app.loader.init_worker()

File "/usr/local/lib/python3.9/site-packages/celery/loaders/base.py", line 111, in init_worker

self.import_default_modules()

File "/usr/local/lib/python3.9/site-packages/celery/loaders/base.py", line 105, in import_default_modules

raise response

File "/usr/local/lib/python3.9/site-packages/celery/utils/dispatch/signal.py", line 276, in send

response = receiver(signal=self, sender=sender, **named)

File "/usr/local/lib/python3.9/site-packages/celery/fixups/django.py", line 82, in on_import_modules

self.worker_fixup.validate_models()

File "/usr/local/lib/python3.9/site-packages/celery/fixups/django.py", line 121, in validate_models

run_checks()

File "/usr/local/lib/python3.9/site-packages/django/core/checks/registry.py", line 70, in run_checks

new_errors = check(app_configs=app_configs, databases=databases)

File "/usr/local/lib/python3.9/site-packages/django/core/checks/urls.py", line 13, in check_url_config

return check_resolver(resolver)

File "/usr/local/lib/python3.9/site-packages/django/core/checks/urls.py", line 23, in check_resolver

return check_method()

File "/usr/local/lib/python3.9/site-packages/django/urls/resolvers.py", line 408, in check

for pattern in self.url_patterns:

File "/usr/local/lib/python3.9/site-packages/django/utils/functional.py", line 48, in __get__

res = instance.__dict__[self.name] = self.func(instance)

File "/usr/local/lib/python3.9/site-packages/django/urls/resolvers.py", line 589, in url_patterns

patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)

File "/usr/local/lib/python3.9/site-packages/django/utils/functional.py", line 48, in __get__

res = instance.__dict__[self.name] = self.func(instance)

File "/usr/local/lib/python3.9/site-packages/django/urls/resolvers.py", line 582, in urlconf_module

return import_module(self.urlconf_name)

File "/usr/local/lib/python3.9/importlib/__init__.py", line 127, in import_module

return _bootstrap._gcd_import(name[level:], package, level)

File "<frozen importlib._bootstrap>", line 1030, in _gcd_import

File "<frozen importlib._bootstrap>", line 1007, in _find_and_load

File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked

File "<frozen importlib._bootstrap>", line 680, in _load_unlocked

File "<frozen importlib._bootstrap_external>", line 790, in exec_module

File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed

File "/code/footballdata/urls.py", line 23, in <module>

from api import views

File "/code/api/views.py", line 21, in <module>

from .mixins import CacheMixin

File "/code/api/mixins.py", line 10, in <module>

class CacheMixin(object):

File "/code/api/mixins.py", line 16, in CacheMixin

def list(self, request):

File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 63, in _dec

return _multi_decorate(decorator, obj)

File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 47, in _multi_decorate

_update_method_wrapper(_wrapper, dec)

File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 17, in _update_method_wrapper

def dummy(*args, **kwargs):

File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 117, in _decorator

middleware = middleware_class(view_func, *m_args, **m_kwargs)

File "/usr/local/lib/python3.9/site-packages/django/middleware/cache.py", line 174, in __init__

super().__init__(get_response)

File "/usr/local/lib/python3.9/site-packages/django/middleware/cache.py", line 67, in __init__

super().__init__(get_response)

File "/usr/local/lib/python3.9/site-packages/django/middleware/cache.py", line 133, in __init__

self.cache = caches[self.cache_alias]

File "/usr/local/lib/python3.9/site-packages/django/core/cache/__init__.py", line 79, in __getitem__

cache = _create_cache(alias)

File "/usr/local/lib/python3.9/site-packages/django/core/cache/__init__.py", line 52, in _create_cache

raise InvalidCacheBackendError(

django.core.cache.backends.base.InvalidCacheBackendError: Could not find backend 'django_redis.cache.RedisCache': No module named 'django_redis'

安装程序

将Django与Django redis一起使用==4.12。1和redis==3.5。3.使用docker compose进行停靠。

我的docker-compose.yml：

version: "3.9"
   
services:
  postgresdb:
    image: postgres
    container_name: postgresdb
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    volumes: 
      - pgdata:/code/pgdata/

  redisdb:
    image: redis
    container_name: redisdb
    volumes: 
      - redisdata:/code/redisdata/

  web:
    build: .
    container_name: django
    command: python manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    environment: 
      - CELERY_BROKER=redis://redisdb:6379/0
      - CELERY_BACKEND=redis://redisdb:6379/0
    ports:
      - "8000:8000"
    depends_on:
      - postgresdb
      - redisdb

  celery:
    build: .
    container_name: celery
    command: celery -A footballdata worker -l INFO
    volumes: 
      - .:/code
    depends_on: 
      - web
      - redisdb

volumes: 
  pgdata:
  redisdata:

在我的设置中。py：

        CACHES = {
        "default": {
            "BACKEND": "django_redis.cache.RedisCache",
            "LOCATION": "redis://redisdb:6379/",
            "OPTIONS": {
                "CLIENT_CLASS": "django_redis.client.DefaultClient",
            }
        }
    }

CACHE_TTL = 30

# Celery stuff 
CELERY_BROKER_URL = os.environ.get("CELERY_BROKER", "redis://redisdb:6379/0")
CELERY_RESULT_BACKEND = os.environ.get("CELERY_BROKER", "redis://redisdb:6379/0")
CELERY_ACCEPT_CONTENT = ['application/json']
CELERY_TASK_SERIALIZER = 'json'
CELERY_RESULT_SERIALIZER = 'json'
CELERY_TIMEZONE = 'Europe/Warsaw'

# Redis 
REDIS_HOST = 'redisdb'
REDIS_PORT = 6379

是什么导致容器崩溃

使用django的cache\u页面decorator。我有一个RESTAPI，我想连接到缓存。我使用简单的mixin缓存页面：

CACHE_TTL = getattr(settings, 'CACHE_TTL', DEFAULT_TIMEOUT)

class CacheMixin(object):
    """
    Caching for REST API views.
    Caches list and retrieve results of the view for the specified TTL.
    """
    @method_decorator(cache_page(CACHE_TTL))
    def list(self, request):
        return super().list(request)

    @method_decorator(cache_page(CACHE_TTL))
    def retrieve(self, request, pk):
        return super().retrieve(request, pk)

用这个调味品弄坏了我的芹菜容器。当我注释掉这段代码时，容器运行得很好。

据我所见，服务器试图创建或连接到我在settings.py中指定的缓存后端，但没有找到django_redis模块。这很奇怪，因为我已经安装了它，并在我的requirements.txt文件中。

更奇怪的是（至少对我来说）其他容器工作得很好——缓存mixin也工作得很好！当我连接到redis容器并用这个mixin缓存页面时，它正确地存储在缓存中。只是芹菜因为某种原因坏了。

我试过的

环顾四周，寻找类似的问题。我找到的最接近的是这个问题。但是，这个问题与six包有关。我的追踪是不同的。除此之外，我还没有找到任何对我有帮助的东西。

恢复到较旧版本的django redis（3.6.6）和/或redis（2.10）-我发现过去有些人与django和redis存在兼容性问题。这对我也不起作用。

有没有人有过类似的问题？如果有任何想法，我将不胜感激。

岳英耀

2023-03-14

好吧，我解决了。结果证明它比我想象的要简单（通常是这样）。我应该听一下错误信息，知道它来自哪里。

发生的事情是，我在需求文件中做了一些更改，但我没有使用docker compose-up--build重建容器，而是使用docker build重建容器。因此，我猜芹菜容器没有正确更新所需的包装。

所以这个错误本质上是因为我对docker vs docker-comment缺乏理解。

芹菜容器在使用django cache_页面时崩溃（InvalidCacheBackendError）

共有1个答案

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