Running Services
- Kubernetes
- What It Does:
- Kubernetes manages the deployment, scaling, and operation of containerized applications.
- Role in Logging:
- It generates logs from various workloads (pods, services, etc.).
- Provides APIs for log collection via kubectl logs or via log agents installed on nodes.
- What It Does:
- Grafana
- What It Does:
- Grafana is a visualization and monitoring tool. It creates dashboards and panels for metrics and logs.
- Role in Logging:
- Acts as a user interface to query and visualize logs stored in Loki.
- Connects to Loki as a data source for log analysis.
- What It Does:
- Loki
- What It Does:
- Loki is a log aggregation system designed to work like Prometheus but for logs.
- Role in Logging:
- Stores log data in a structured format (optimized for fast retrieval).
- Supports queries via Grafana, allowing users to search and filter logs using a PromQL-like syntax.
- What It Does:
- Promtail
- What It Does:
- Promtail is an agent that collects logs from local files and forwards them to Loki.
- Role in Logging:
- Deployed on Kubernetes nodes to read logs from pod log files or the system journal.
- Adds Kubernetes metadata (like pod labels) to logs for better filtering and correlation in Grafana.
- What It Does:
- Fluentd
- What It Does:
- Fluentd is a log processor and forwarder. It supports complex data pipelines.
- Role in Logging:
- Collects logs from various sources (applications, Kubernetes nodes).
- Can process, transform, and enrich logs (e.g., parsing JSON, adding custom metadata).
- Forwards logs to Loki or another storage backend.
- What It Does:
- Fluent Bit
- What It Does:
- Fluent Bit is a lightweight log forwarder (a more efficient version of Fluentd for resource-constrained environments).
- Role in Logging:
- Deployed as a sidecar or daemonset in Kubernetes.
- Collects logs from Kubernetes workloads or nodes.
- Forwards logs to Fluentd (for further processing) or directly to Loki.
- What It Does:
How They Work Together
-
Kubernetes generates logs from its nodes, pods, and system components.
-
Promtail, Fluent Bit, or Fluentd agents run on Kubernetes nodes:
- They collect logs from different sources (e.g., container stdout, application logs).
- These agents enrich logs with Kubernetes metadata (namespace, pod labels).
- Logs are then forwarded to Loki for storage.
-
Loki stores the logs, indexing them for efficient querying.
-
Grafana queries Loki:
- Grafana connects to Loki as a data source.
- Users search logs through the Grafana interface using filters and visualizations.
Simplified Workflow
- Logs generated: Kubernetes workloads (pods, containers) produce logs.
- Log collection: Fluentd, Fluent Bit, or Promtail collect and process logs.
- Log storage: Logs are sent to Loki for indexing and storage.
- Log visualization: Grafana queries Loki and displays logs for analysis.
This setup enables scalable, efficient log collection and real-time monitoring.