Design of an auto-scaling mechanism for Pub/Sub microservices

In the past, enterprise application services were built on monolithic architecture. However, monolithic architectures bundle all features into a single application service, resulting in high coupling. If one component within the service fails, the entire application becomes unavailable. As application architectures grew in size, maintenance and management became increasingly difficult. Consequently, enterprises have gradually adopted microservices architectures, breaking original monolithic applications into multiple independent microservices. These microservices communicate with each other via APIs (Application Programming Interfaces) or Pub/Sub (Publish/Subscribe) mechanisms. To ensure reliability, developers specify Service Level Indicators (SLIs) such as response time within Service-Level Objectives (SLOs). This proposed design an auto-scaling mechanism that supports Pub/Sub communication: when an application’s response time exceeds the SLI threshold defined in its SLO, the auto-scaling mechanism is triggered to enhance reliability.