Beyond the Limits: Scaling Kubernetes Controllers Horizontally - Tim Ebert, STACKIT
Tim Ebert, STACKIT
KubeCon + CloudNativeCon Europe 2025 · Session
In the realm of Kubernetes, controllers and operators are fundamental to achieving the desired declarative state management. They are the workhorses that observe, react, and enforce the configurations defined by users. However, a long-standing challenge for these critical components has been their inherent limitation in horizontal scalability. Due to the need to prevent conflicting reconciliations, most Kubernetes controllers rely on **leader election**, an active-passive High Availability (HA) mechanism that designates only one instance as the active leader at any given time, preventing true scale-out.
AI review
This talk presents a genuinely innovative and deeply researched solution to a long-standing architectural bottleneck in Kubernetes controller scalability. By elegantly adapting distributed database sharding principles and leveraging native Kubernetes API primitives, Tim Ebert delivers a robust mechanism for true horizontal scaling, moving beyond the inherent limitations of active-passive leader election. The detailed architecture, complete with dynamic membership, object reassignment, and a clever handover mechanism, promises near-linear performance gains, making it an indispensable…