The rapid adoption of microservices, cloud-native architectures, and container orchestration platforms has significantly increased the complexity of enterprise distributed systems, making traditional monitoring approaches inadequate for ensuring reliability and performance. In response to these challenges, observability has emerged as a critical paradigm for understanding system behavior by enabling operators to infer internal states from externally observable signals. Observability extends beyond conventional monitoring by emphasizing rich contextual data, correlation across components, and exploratory analysis of system behavior under both normal and failure conditions. This paper presents a systematic and comprehensive review of observability in modern distributed systems, with particular emphasis on enterprise-scale, microservices-based environments. The study examines the foundational pillars of observability—metrics, logs, and distributed traces—alongside network telemetry as an increasingly important complementary signal for understanding communication behavior and performance bottlenecks. Architectural models for telemetry collection, including agent-based, sidecar-based, and platform-integrated approaches, are analyzed with respect to scalability, performance overhead, and operational complexity. The paper further explores integrated observability platforms that aim to unify heterogeneous telemetry sources, enabling cross-signal correlation, end-to-end visibility, and more effective root cause analysis. Operational implications of observability-driven practices are discussed in the context of reliability engineering, capacity planning, and incident response. Additionally, the review highlights key challenges and limitations faced by observability systems in 2022, including high data volume and cardinality, cost constraints, data quality issues, and privacy and security concerns. Emerging trends such as standardization through OpenTelemetry, early adoption of machine learning for anomaly detection, and observability in containerized and service-mesh environments are also examined. By synthesizing existing research and industry practices, this paper provides a structured foundation for understanding observability as a core capability for operating reliable, scalable, and maintainable distributed systems, while identifying open research directions and practical considerations for future observability solutions.
Vinod Kumar Jangala (Fri,) studied this question.