Layer Aware Microservice Placement and Request Scheduling at the Edge

Container-based microservice has emerged as a promising technique in promoting edge computing elasticity. At the runtime, microservices, encapsulated in form of container images, need to be frequently downloaded from remote registries to local edge servers, which may incur significant overhead in terms of excessive download traffic and large local storage. Given the limited resources at the edge, it is of critical importance to minimize such overhead in order to enhance microservice offerings. A distinctive feature in container-based microservice, which has not been exploited, is that microservice images are in layered structure and common layers can be shared by co-located microservices. In this paper, we study a layer aware micro-service placement and request scheduling at the edge. Intuitively, throughput and number of hosted microservices can be significantly increased by layer sharing between co-located images. We formulate this into an optimization problem with approximate submodularity, and prove this to be NP-hard. We design an iterative greedy algorithm with guaranteed approximation ratio. Extensive experiments validate the efficiency of our method, and the results demonstrate that the number of placed microservices can be increased by 27.61% and the microservice throughput can be improved by 73.13%, respectively, in comparison with the state-of-the-art microservice placement strategy.