Elasticity Debt: A Debt-Aware Approach to Reason about Elasticity Decisions in the Cloud

Cloud elasticity provides the underlying primitives to dynamically acquire and release shared computational resources on demand. Therefore, elasticity constantly takes adaptation decisions to adjust the resource provisioning constrained by quality of service and operating costs minimization. However, dynamic trade-offs for resource provisioning rarely consider the value of the adaptation decisions under uncertainty. Part of the problem stems from the lack of a utility-driven model to reason about it. In this paper, we introduce the concept of elasticity debt as an approach to reason about elasticity decisions from a utility-driven perspective, where we apply the technical debt metaphor in the context of cloud elasticity. Moreover, we extended CloudSim as a proof of concept to show that a debt-aware elasticity decision-making can achieve a higher utility over time. We provide an elasticity conceptual model that links the key factors to consider when adapting resource provisioning and the potential debts incurred by these decisions. We propose a new perspective to value elasticity decisions in the uncertain cloud environment by introducing a technical debt perspective.