Loki and Promtail Logging Guide¶

This page explains the logging flow in the monitoring lab.

Important Files¶

• loki/loki-config.yml
• promtail/promtail-config.yml

How the Flow Works¶

1. Promtail reads logs from configured sources.
2. Promtail adds labels and forwards the logs.
3. Loki stores and indexes the log streams.
4. Grafana queries Loki for dashboards and exploration.

Log Sources in This Setup¶

• Host log files from /var/log
• Docker container logs from /var/lib/docker/containers

Why Loki Fits Well¶

• Works cleanly with Grafana
• Uses labels effectively
• Is lighter than some larger log platforms for small labs

What to Validate¶

• Promtail can read the configured paths
• Loki is healthy
• Grafana can query the Loki data source
• Labels are useful enough to filter logs clearly

Practical Improvements¶

• Add better labels for service, host, and environment
• Set retention rules
• Reduce noisy low-value logs
• Parse structured logs where possible

Quick Check¶

docker compose logs -f promtail
docker compose logs -f loki
curl http://localhost:3100/ready