Session Storage in Kubernetes with Memcached

Session storage is a key consideration when deploying applications in Kubernetes. Ensuring fast, efficient, and reliable session management is essential for maintaining performance in cloud-native environments. Here's why Memcached is a preferred solution for managing sessions.

Issue 1: Sessions Shouldn't Be Stored in the Database

Storing session data in a relational database (DB) introduces unnecessary query load and latency. Instead, sessions should be stored in lightweight, fast-access systems like cookies or an in-memory store, which improves performance.

Issue 2: Session Driver – Memcached vs. Cookie

• Cookie-based sessions: Store data client-side (in the browser), which is simple but comes with size limitations (~4KB per cookie).
• Memcached-based sessions: Store sessions server-side, providing several advantages:
  • Faster retrieval than querying a database.
  • Shared access across multiple replicas, ensuring consistency.
  • No file storage required, which is essential in Kubernetes, where pods are ephemeral.

Memcached is the ideal choice for session storage in production due to its performance and simplicity.

Issue 3: Scalability with Multiple Replicas

When session data is stored in files, it’s only accessible by a single pod. As Kubernetes scales horizontally with multiple replicas, each pod must have access to the same session data. Memcached solves this by providing centralised, in-memory storage that is accessible across all replicas.

What About Redis?

While Redis offers persistence and more advanced data structures, Memcached is simpler, has lower memory overhead, and performs better for session management, making it the preferred choice in most cases.

Conclusion

For Kubernetes-based applications, Memcached provides a fast, scalable, and simple solution for session storage. It ensures better performance, supports shared access across replicas, and avoids the complexity of database or file-based solutions. Memcached is the ideal choice for managing sessions in cloud-native environments.