Kubernetes logging provides essential visibility into the ongoing activities of a cluster. While the platform's dynamic nature is its greatest strength, it also introduces significant observability challenges. Effective logging allows teams to troubleshoot production issues, mitigate security risks, and maintain overall application health.
How Logging Functions in Kubernetes
Kubernetes treats container logs as standard output (stdout) and standard error (stderr) streams. These are captured by the container runtime and exposed via the Kubernetes API.
The kubelet agent on each node manages these logs, retrieving them when requested by the API server. However, this local storage approach has limitations: logs are deleted when pods are evicted or crashed, and multi-node aggregation is difficult without external tools.
Key Log Types in a Cluster
Application Logs
Generated by containerized apps to provide insight into behavior, errors, performance metrics, and business logic.
Component Logs
Data from the API server, Scheduler, Controller Manager, and etcd to diagnose cluster health.
Audit Logs
Security-relevant records answering who did what, when, and where within the API server.
Events
Objects detailing the lifecycle of pods and nodes, including scheduling decisions and warning events.
Primary Logging Architectures
- Node-Level Agent: A dedicated agent (e.g., Fluentd) runs on every node as a
DaemonSetto collect and forward logs. - Sidecar Container: A dedicated logging container runs within the pod to tail and process log files from the main application.
- Direct Application Logging: Applications send data directly to a backend, bypassing standard Kubernetes mechanisms.
Best Practices for Modern Environments
- Centralize Everything: Consolidate logs from applications and cluster components into one system to streamline troubleshooting.
- Implement Structured Logging: Use key-value pairs (like JSON) to make logs machine-readable and easily searchable.
- Manage Retention and Rotation: Define policies to control storage costs and prevent disk space exhaustion on nodes.
- Enforce Secure Access: Use Role-Based Access Control (RBAC) to ensure sensitive log data is only visible to authorized personnel.
- Isolate Environments: Use separate clusters for dev and production to prevent high-volume testing logs from impacting production visibility.
Conclusion: Implementing with Graylog
Graylog provides a scalable platform to centralize and manage Kubernetes logs effectively. It offers flexible index rotation, automated archiving, and cost-efficient storage management to help organizations meet both operational and compliance requirements.
About Graylog
At Graylog, our vision is a secure digital world where organizations of all sizes can effectively guard against cyber threats. We’re committed to turning this vision into reality by providing Threat Detection & Response that sets the standard for excellence. Our cloud-native architecture delivers SIEM, API Security, and Enterprise Log Management solutions that are not just efficient and effective—whether hosted by us, on-premises, or in your cloud—but also deliver a fantastic Analyst Experience at the lowest total cost of ownership. We aim to equip security analysts with the best tools for the job, empowering every organization to stand resilient in the ever-evolving cybersecurity landscape.
About Version 2 Limited
Version 2 Digital is one of the most dynamic IT companies in Asia. The company distributes a wide range of IT products across various areas including cyber security, cloud, data protection, end points, infrastructures, system monitoring, storage, networking, business productivity and communication products.
Through an extensive network of channels, point of sales, resellers, and partnership companies, Version 2 offers quality products and services which are highly acclaimed in the market. Its customers cover a wide spectrum which include Global 1000 enterprises, regional listed companies, different vertical industries, public utilities, Government, a vast number of successful SMEs, and consumers in various Asian cities.