Django sessions stop working after Redis implementation

Question

I Havve implemented redis using this link and after this session must bne stored in redis instaed of db. After configuration when I restart my app . I am getting hey error for my sessions.

e.g., Let say IN function A I declared a session and when I visit another link from browser and try to fetch same session in view the session is gone its not there. even no session keys exist . request.session.keys() is blank.

Here is my redis configuration:

Cache server settings

REDIS_PROT = "redis://"
REDIS_HOST = "127.0.0.1"
REDIS_PORT = 6379
REDIS_DB = 0

REDIS_CACHE_SERVER = REDIS_PROT + REDIS_HOST + ":" + str(REDIS_PORT) + "/" + str(REDIS_DB)
REDIS_CACHEALOT_SERVER = REDIS_PROT + REDIS_HOST + ":" + str(REDIS_PORT) + "/" + str(REDIS_DB + 3)

DJANGO_REDIS_IGNORE_EXCEPTIONS = True

CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": REDIS_CACHE_SERVER,
        "OPTIONS": {
            "PARSER_CLASS": "redis.connection.HiredisParser",
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
            "COMPRESS_MIN_LEN": 10,
            "SOCKET_CONNECT_TIMEOUT": 5,  # in seconds
            "SOCKET_TIMEOUT": 5,  # in seconds
        }
    },
    "cachealot": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": REDIS_CACHEALOT_SERVER,
        "OPTIONS": {
            "PARSER_CLASS": "redis.connection.HiredisParser",
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
            "COMPRESS_MIN_LEN": 10,
            "SOCKET_CONNECT_TIMEOUT": 5,  # in seconds
            "SOCKET_TIMEOUT": 5,  # in seconds
        }
    }
}

# CacheALot service settings 

CACHALOT_ENABLED = True
CACHALOT_CACHE   = 'cachealot'

# Django Redis Session App Configuration 

SESSION_REDIS_HOST = REDIS_HOST
SESSION_REDIS_PORT = REDIS_PORT
SESSION_REDIS_DB = REDIS_DB + 4
#SESSION_REDIS_PASSWORD = 'password'
SESSION_REDIS_PREFIX = 'session'

SESSION_ENGINE = 'redis_sessions.session'
# If you prefer domain socket connection, you can just add this line instead of SESSION_REDIS_HOST and SESSION_REDIS_PORT.
#SESSION_REDIS_UNIX_DOMAIN_SOCKET_PATH = '/var/run/redis/redis.sock'

# Celery Configurations
REDIS_CELERY_BROKER_SERVER =  REDIS_PROT + REDIS_HOST + ":" + str(REDIS_PORT) + "/" + str(REDIS_DB + 1)
REDIS_CELERY_RESULT_SERVER = REDIS_PROT + REDIS_HOST + ":" + str(REDIS_PORT) + "/" + str(REDIS_DB + 2)

BROKER_URL = REDIS_CELERY_BROKER_SERVER
CELERY_RESULT_BACKEND = REDIS_CELERY_RESULT_SERVER
CELERY_ALWAYS_EAGER=False

Any idea why I am getting key errors for django sessions.

Answer 1

Seems you're doing awfully much for simply enabling cached sessions. Why are you also using django-redis-sessions, django-cachalot in addition to django-redis?

Let's simplify with a minimal config, that works for me, using only django-redis. I'm following their guide, and Django's documentation on setting up sessions and using cached sessions:

CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379/1",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
        }
    }
}
SESSION_ENGINE = 'django.contrib.sessions.backends.cache'

That's it, test it by requesting a view and inspecting request.session or, if you're outside of request, using your session store:

>>> from django.contrib.sessions.backends.cache import SessionStore
>>> s = SessionStore(session_key='ff882814010ccbc3c870523934fee5a2')
>>> s.save()
>>> s.session_key
'ff882814010ccbc3c870523934fee5a2'
>>> s.session_data
'KGRwMQpTJ19hdXRoX3VzZXJfaWQnCnAyCkkxCnMuMTExY2ZjODI2Yj...'
>>> s.get_decoded()
{'user_id': 42}