Django, Redis & AWS ElastiCache primary/replica cluster

AWS’s ElastiCache service is a convenient way to launch a Redis cluster. If you’re using Django, both django-redis-cache and django-redis packages support an ElastiCache Redis instance. If you are launching ElastiCache Redis with any amount of replicas, some additional master-slave configuration is needed in your Django settings.

Here is an example of an ElastiCache Redis cluster with a primary instance and two replicas:

The following is an example of the correct settings for this cluster if you’re using django-redis-cache backend:

CACHES = {
    'default': {
        'BACKEND': 'redis_cache.RedisCache',
        'LOCATION': [
            "test-001.730tfw.0001.use1.cache.amazonaws.com:6379",
            "test-002.730tfw.0001.use1.cache.amazonaws.com:6379",
            "test-003.730tfw.0001.use1.cache.amazonaws.com:6379"
        ],
        'OPTIONS': {
            'DB': 0,
            'MASTER_CACHE': "test-001.730tfw.0001.use1.cache.amazonaws.com:6379"
        },
    }
}

https://django-redis-cache.readthedocs.io/en/latest/advanced_configuration.html#master-slave-setup

2 thoughts on “Django, Redis & AWS ElastiCache primary/replica cluster”

  1. Hi Nick,

    I have a similar master slave set up for redis and i am using Django redis cache.
    I have 1 master and 2 slave in location settings file. How do i connect to only slave if required?

    1. Sorry, been a while since I used anything relating to this. My guess is that this is all handled internally within django-redis-cache.

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