# Loki Labels Reference

In Grafana Loki, each log stream is identified by a small set of **indexed labels**. Additional context is attached to individual log lines as **structured metadata**. Both can be used to filter logs in LogQL queries, but only indexed labels belong inside the stream selector `{…}`.

## Indexed labels

Indexed labels form the stream selector and are the only labels you should place inside the curly braces `{…}` of a LogQL query. In Nais, only the following labels are indexed:

| Label | Description | Applicable to |
| --- | --- | --- |
| `service_name` | The name of the application that generated the log line. | All |
| `service_namespace` | The namespace of the application that generated the log line. | All |
| `k8s_cluster_name` | The name of the Kubernetes cluster that generated the log line. | Kubernetes |

Example stream selector using indexed labels only:

```logql
{service_name="my-app", service_namespace="my-team", k8s_cluster_name="prod-gcp"}
```

## Structured metadata

Everything else is attached to each log line as structured metadata rather than being indexed. Structured metadata is fully filterable, but it **must not** be placed inside the stream selector `{…}`. Instead, filter on it later in the pipeline with a label-filter expression:

```logql
{service_name="my-app"} | detected_level="error"
```

| Field | Description | Applicable to |
| --- | --- | --- |
| `detected_level` | The log level detected by the log parser. | All |
| `k8s_container_name` | The name of the Kubernetes container that generated the log line. | Kubernetes |
| `k8s_pod_name` | The name of the Kubernetes pod that generated the log line. | Kubernetes |
| `k8s_node_name` | The name of the Kubernetes node that generated the log line. | Kubernetes |
| `collector_name` | The name of the log collector that ingested the log line. | All |
| `kind` | The kind of log line. Can be `exception`, `event`, `log` or `measurement`. | Faro SDK |