Microservices architecture advocates decentralized data ownership for building software systems. Particularly, in the Database per Service pattern, each microservice is supposed to maintain its own database and to handle the data related to its functionality. When implementing microservices in practice, however, there seems to be a paradox: The de facto technology (i.e., containerization) for microservice implementation is claimed to be unsuitable for the microservice component (i.e., database) in production environments, mainly due to the data persistence issues (e.g., dangling volumes) and security concerns. As a result, the existing discussions generally suggest replacing database containers with cloud database services, while leaving the on-premises microservice implementation out of consideration. After identifying three statelessness-dominant application scenarios, we proposed container-native data persistence as a conditional solution to enable resilient database containers in production. In essence, this data persistence solution distinguishes stateless data access (i.e., reading) from stateful data processing (i.e., creating, updating, and deleting), and thus it aims at the development of stateless microservices for suitable applications. In addition to developing our proposal, this research is particularly focused on its validation, via prototyping the solution and evaluating its performance, and via applying this solution to two real-world microservice applications. From the industrial perspective, the validation results have proved the feasibility, usability, and efficiency of fully containerized microservices for production in applicable situations. From the academic perspective, this research has shed light on the operation-side micro-optimization of individual microservices, which fundamentally expands the scope of “software micro-optimization” and reveals new research opportunities.

Cloud computing has made federated database systems (FDBS) significantly more practical to implement than in the past. As part of a recent Web-based Geographic Information System (WebGIS) project, we are employing cloud-native technologies (from the container ecosystem) to develop a federated database (DB) infrastructure, to help manage and utilise the distributed and various geospatial data. Unfortunately, there seem to be inherent challenges and complexity of applying the container and Kubernetes technologies to building and running DB systems. Considering that most of the geospatial and theme data are pre-obtained and fixed in our WebGIS project, we decided to focus on the read-only user queries and still resort to Kubernetes to implement an FDBS instance to use. Unlike the de facto practices (e.g., using the StatefulSets mechanism, extending Kuberentes APIs, or employing KubeFed), our solution for Kubernetes-aided FDBS simplifies the tech stack by investigating the fractal object of federated data management, inclusively containerising DB instances, and using the lightweight Deployment mechanism to handle stateless DB containers. Overall, this research not only reveals an easy-to-implement approach to constructing read-only components in a fully-fledged FDBS, but also proposes and demonstrates a novel methodology for FDBS investigations.