Loki

Loki is Grafana’s log store. Nexus queries it to read what your services logged around the time of an incident: the errors, the warnings, the request that failed.

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What we support

A Loki data source gives Nexus two capabilities, both queried with LogQL:

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Filtering beyond your label index

Loki only indexes the stream labels you choose, but plenty of useful detail lives outside that index: in structured metadata attached to each entry, and in fields parsed out of the log body (for example with | json). Nexus uses all three, so it can filter on attributes you never indexed, not just your labels: a request ID, a status code, a customer.

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Fast queries on high-volume logs

The cost of a Loki query comes down to its stream selector: too broad and it’s slow or rejected, too narrow and it misses data. Nexus scopes the selector to the streams that matter, using what it’s learned about your labels and their cardinality. Queries stay fast even on noisy, high-volume logs. If a query does time out, Nexus narrows it and tries again rather than giving up. Nexus learns this structure automatically: your labels, structured metadata, parsed fields, and which labels are high-cardinality. How that works is covered in How telemetry works.

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Connecting Loki

Connect Grafana, and Nexus discovers every Loki data source behind it automatically, using Grafana’s own credentials, with nothing separate to configure. Discovered Loki data sources start disabled. Log queries can be broad, so you opt in deliberately: enable the Loki data sources your team uses from your telemetry settings. If an enabled Loki data source holds no log data yet, Nexus sets it aside rather than run queries that can’t return anything. It starts using the source once logs arrive.

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Best practice

• Connect the Grafana dashboards that query Loki. Nexus learns your real log query patterns from them, which makes Loki queries more accurate.
• Enable the Loki data sources your responders reach for during incidents, rather than every source available.

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