Instability in Geo-Distributed Kubernetes Federation: Causes and Mitigation

As resources in geo-distributed environments are typically located in remote sites characterized by high latency and intermittent network connectivity, delays and transient network failures are common between the management layer and the remote resources. In this paper, we show that delays and transient network failures coupled with static configuration, including the default configuration parameter values, can lead to instability of application deployments in Kubernetes Federation, making applications unavailable for long periods of time. Leveraging on the benefits of configuration tuning, we propose a feedback controller to dynamically adjust the concerned configuration parameter to improve the stability of application deployments without slowing down the detection of hard failures. We show the effectiveness of our approach in a geo-distributed setup across five sites of Grid'5000, bringing system stability from 83-92% with no controller to 99.5-100% using the controller.