Running Services

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.

How They Work Together

1. Kubernetes generates logs from its nodes, pods, and system components.

2. 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.

3. Loki stores the logs, indexing them for efficient querying.

4. Grafana queries Loki:

   • Grafana connects to Loki as a data source.
   • Users search logs through the Grafana interface using filters and visualizations.

Simplified Workflow

1. Logs generated: Kubernetes workloads (pods, containers) produce logs.
2. Log collection: Fluentd, Fluent Bit, or Promtail collect and process logs.
3. Log storage: Logs are sent to Loki for indexing and storage.
4. Log visualization: Grafana queries Loki and displays logs for analysis.

This setup enables scalable, efficient log collection and real-time monitoring.