Grafana Loki
Multi-tenant log aggregation system inspired by Prometheus
...Unlike other logging systems, Loki is built around the idea of only indexing metadata about your logs: labels (just like Prometheus labels). Log data itself is then compressed and stored in chunks in object stores such as S3 or GCS, or even locally on the filesystem. A small index and highly compressed chunks simplifies the operation and significantly lowers the cost of Loki. Loki supports multi-tenancy so that data between tenants is completely separated. Multi-tenancy is achieved through a tenant ID (which is represented as an alphanumeric string). When multi-tenancy mode is disabled, all requests are internally given a tenant ID of “fake”.