Diffusing High-level SLO in Microservice Pipelines

Complex interactions within microservice architectures obfuscate the implications of individual services to high-level requirements. This becomes even more grave for multi-tenant and multi-vendor scenarios, like Edge computing, where different stakeholders might specify opposing Service Level Objectives (SLOs), e.g., minimizing both energy consumption and response time. To avoid contradictions within SLOs and to infer how SLOs can be fulfilled, this paper presents a methodology that diffuses high-level SLOs into multiple lower levels of SLOs and parameter assignments. Thus, it becomes clear how individual sub-processes contribute to high-level SLOs, and how these must be configured to foster their fulfillment. We evaluated our methodology for several microservice pipelines, where the challenge is to ensure multiple high-level SLOs (e.g., customer satisfaction) by finding and constraining all influential factors. The results show that by inferring multiple layers of lower-level constraints, we can fulfill high-level SLOs up to 100%. Notably, we could extract that the restrictiveness of low-level SLOs and the occurrence of conflicts have a severe impact on SLO fulfillment.