SLO-aware Prioritization of Orchestration Times for Containerized Services

In this article, we present a timing analysis of orchestration times for containerized services, revealing the inability of current container orchestrators to fully prioritize services under concurrent requests. The analysis identifies the sources of orchestration delays that impact services to be prioritized potentially violating their Service Level Objectives (SLOs). Based on the findings of the timing analysis, we highlight three alternative SLO-aware orchestration system designs aimed at preventing and/or mitigating delays for high-priority services. We provide principles and guidelines that must drive the implementation of these designs. We then introduce Ulysses, a Kubernetes-based prototype embodying the simplest of the three designs. Ulysses modifies the core Kubernetes control plane components to manage events synchronously and with fixed priority. Through experiments conducted with both synthetic workloads and a containerized cloud-native 5G core network, we demonstrate that Ulysses ensures stable orchestration times for high-priority services, with a reduction of up to 78% under high orchestration load.