In recent years, the reliance on digital services in critical sectors such as e-commerce, financial services, e-government, and healthcare applications has made availability a requirement as important as performance and security. Recent outages of major cloud platforms and widely used services such as Amazon Web Services (AWS) affected approximately 500 companies due to the disruption—some of which in Brazil included iFood, Mercado Livre, Itaú, and others. Even though they were short-lived, these outages caused global downtime and resulted in millions in losses, highlighting how just a few minutes of disruption can compromise entire business chains and user trust. In this scenario, availability and recovery time metrics have evolved from being merely operational indicators to becoming strategic inputs in capacity planning and the definition of service level agreements (SLAs).
This paper, authored by Jonas César Gomes Nunes (UFPI), Iure de Sousa Fé (UFPI), Lucas Lopes (UFPI), José Miqueias (UFPI), Elias P. Duarte Jr. (UFPR), and Francisco Airton Silva (UFPI), introduces Chaos-K8s, an innovative tool developed to systematically assess availability in Kubernetes clusters.
The solution focuses on automating infrastructure discovery and the empirical calibration of recovery times, allowing administrators to test failures in the control plane, nodes, and pods (a pod is a small part of an application containing everything it needs to function). By performing controlled simulations, the system helps quantify how different configurations impact the end-user experience and service resilience.
The study validates the tool’s effectiveness through mathematical modeling, demonstrating a high degree of statistical accuracy between practical tests and theoretical results. Ultimately, the work offers a structured methodology for companies to predict outages and optimize the robustness of their cloud operations.
Automatic Discovery and Calibration
The tool automatically maps the cluster components (control plane components such as etcd and kube-apiserver, worker nodes, and deployed applications) to generate an initial configuration without manual effort. Unlike other tools that use generic values, Chaos-K8s can perform a calibration phase where it injects controlled failures to measure the actual Mean Time to Recovery (MTTR) of each component in the specific environment. This ensures that availability calculations reflect the reality of the evaluated infrastructure.
The system acts as an external orchestrator that interacts with the cluster to apply failures at different layers: to Pods—terminating processes to force a restart by Kubernetes; Worker Nodes—restarting critical services such as kubelet and containerd via SSH; and the Control Plane—interrupting core processes such as etcd and kube-apiserver.
Monitoring and Availability Criteria
During testing, Chaos-K8s uses a monitoring module that continuously checks whether the system meets the availability criteria defined by the administrator (for example, the minimum number of healthy replicas of a pod).
If the number of replicas falls below this threshold, the system is considered unavailable.
Validation via Mathematical Modeling
To ensure accuracy, the empirical results obtained by Chaos-K8s are validated using Stochastic Petri Nets (SPN). This modeling allows for a comparison of the data collected in real-world tests with analytical values, providing a robust statistical basis (with 95% confidence in the case study) for availability estimates. Thus, Chaos-K8s not only injects “chaos” but also provides an integrated workflow to quantify the impact of architectural decisions—such as the number of pod replicas—on the system’s overall resilience.
Future Developments
As part of future work, we intend to expand the evaluation of Chaos-K8s in larger-scale enterprise environments, considering real-world applications and more complex workloads. We aim to investigate its behavior during prolonged runs, analyzing availability, reliability, recovery time, and energy consumption, in order to assess its scalability and applicability in real production scenarios.