A Survey on Microservices Trust Models for Open Systems

The microservices architecture (MSA) is a form of distributed systems architecture that has been widely adopted in large-scale software systems in recent years. As with other distributed system architectures, one of the challenges that MSA faces is establishing trust between the microservices, particularly in the context of open systems. The boundaries of open systems are unlimited and unknown, which means that they can be applied to any use case. Microservices can leave or join an open system arbitrarily, without restriction as to ownership or origin, and MSA systems can scale extensively. The organisation of microservices (in terms of the roles they play and the communication links they utilise) can also change in response to changes in the environment in which the system is situated. The management of trust within MSAs is of great importance as the concept of trust is critical to microservices communication, and the operation of an open MSA system is highly reliant on communication between these fine-grained microservices. Thus, a trust model should also be able to manage trust in an open environment. Current trust management solutions, however, are often domain-specific and many are not specifically tailored towards the open system model. This motivates research on trust management in the context of open MSA systems. In this paper, we examine existing microservices trust models, identify the limitations of these models in the context of the principles of open microservices systems, propose a set of qualities for open microservices trust models that emerge from these limitations, and assess selected microservices trust models using the proposed qualities.