Grafana Loki is an open-source log aggregation system, horizontally scalable, highly available, and multi-tenant, inspired by Prometheus. It is designed to be very cost-effective and easy to operate, where traditional log management solutions are often heavy and expensive.

Its key feature: Loki does not index log content, but only a set of labels for each stream. Logs are collected via agents such as Promtail / Grafana Alloy, Fluentd, or the Docker driver, grouped into streams and indexed by labels. You then query them using LogQL, Loki's query language, and can set alerts on critical patterns.

As part of the Grafana ecosystem, Loki natively integrates with dashboards and correlates logs, metrics, and traces for unified observability. Released under the AGPLv3 license, it deploys as a Docker container and requires modest resources relative to the volume processed.