Redis Caching

Redis is an open-source, in-memory data structure store commonly used as a high-performance cache or for session management within applications. Its speed and flexibility make it a popular choice for improving application responsiveness.

Core Concepts

In-Memory Speed Advantage

Redis operates entirely in memory, where data access happens at much faster speeds than traditional disk-based storage. This speed advantage makes Redis particularly valuable for frequently accessed data, enabling applications to serve cached information almost instantaneously.

Internal Access Within Kubernetes

Applications running within the Kubernetes cluster can access Redis using its internal service DNS name. The Redis instance is deployed within the redis namespace, making it accessible to all applications in the cluster.

The typical connection URL format is:

1
redis://redis-master.redis.svc.cluster.local:6379

This URL points to the redis-master service within the redis namespace and connects on the standard Redis port 6379.

Sharing a Redis Instance

Multiple services can share a single Redis instance efficiently. To keep data separate and avoid conflicts, services can use different approaches:

Database separation allows services to use different Redis databases (e.g., service A uses database 0, service B uses database 1). This provides complete logical separation while sharing the same Redis instance.

Key prefixing enables services to use prefixes with their cache keys (e.g., serviceA:some_key, serviceB:other_key). This approach allows for efficient resource utilization while maintaining logical data isolation.

This shared approach works well for most scenarios where services have similar performance and persistence requirements. Separate Redis instances might be considered if services have vastly different performance, persistence, or security requirements.