Energy Efficiency in Microservice Architectures: A Systematic Literature Review
Context. Microservice architectures are widely adopted for building scalable cloud-native systems, enabling independent deployment, fine-grained service composition, and operational elasticity. Problem. Despite growing interest in sustainable software, research on energy efficiency in microservices spans operational, infrastructural, and architectural perspectives, but these are typically addressed in isolation. Existing studies focus on optimisation techniques or measurement approaches, with limited synthesis of how energy efficiency is considered, measured, and addressed at the architectural level. Goal. This study synthesises research on energy-efficient microservices by examining where energy efficiency is considered, how it is measured, and which architectural solutions have been proposed. Method. We conduct a systematic literature review following Kitchenham's guidelines, screening publications from four major digital libraries through a six-stage process with backward and forward snowballing, resulting in 40 primary studies. Results. Energy efficiency is predominantly addressed at runtime through monitoring, scheduling, and resource management, while design-time integration remains limited. Measurement practices are largely infrastructure-oriented and rely on model-based estimation and coarse-grained monitoring. Conclusion. Energy efficiency in microservices is primarily treated as an operational optimisation problem rather than a lifecycle-spanning architectural concern, highlighting the need for earlier architectural integration and improved measurement practices.