Grafana ships with built-in support for [Loki](/docs/loki/latest/), an open-source log aggregation system by Grafana Labs.
This topic explains configuring and querying specific to the Loki data source.
For instructions on how to add a data source to Grafana, refer to the [administration documentation]({{< relref "../../administration/data-source-management/" >}}).
Only users with the organization administrator role can add data sources.
Administrators can also [configure the data source via YAML]({{< relref "#provision-the-data-source" >}}) with Grafana's provisioning system.
Once you've added the Loki data source, you can [configure it]({{< relref "#configure-the-data-source" >}}) so that your Grafana instance's users can create queries in its [query editor]({{< relref "./query-editor/" >}}) when they [build dashboards]({{< relref "../../dashboards/build-dashboards/" >}}), use [Explore]({{< relref "../../explore/" >}}), and [annotate visualizations]({{< relref "./query-editor/#apply-annotations" >}}).
| **Name** | Sets the name you use to refer to the data source in panels and queries. |
| **Default** | Sets the data source that's pre-selected for new panels. |
| **URL** | Sets the HTTP protocol, IP, and port of your Loki instance, such as `http://localhost:3100`. |
| **Allowed cookies** | Defines which cookies are forwarded to the data source. Grafana Proxy deletes all other cookies. |
| **Maximum lines** | Sets the upper limit for the number of log lines returned by Loki. Defaults to 1,000. Lower this limit if your browser is sluggish when displaying logs in Explore. |
To troubleshoot configuration and other issues, check the log file located at `/var/log/grafana/grafana.log` on Unix systems, or in `<grafana_install_dir>/data/log` on other platforms and manual installations.
For example, you can link to your tracing backend directly from your logs, or link to a user profile page if the log line contains a corresponding userId.
These links appear in the [log details]({{< relref "../../explore/logs-integration/#labels-and-detected-fields" >}}).
| **Name** | Sets the field name. Displayed as a label in the log details. |
| **Regex** | Defines a regular expression to evaluate on the log message and capture part of it as the value of the new field. Can contain only one capture group. |
| **URL/query** | Sets the full link URL if the link is external, or a query for the target data source if the link is internal. You can interpolate the value from the field with the `${__value.raw}` macro. |
| **URL Label** | _(Optional)_ Sets a custom display label for the link. This setting overrides the link label, which defaults to the full external URL or name of the linked internal data source. |
| **Internal link** | Defines whether the link is internal or external. For internal links, you can select the target data source from a selector. This supports only tracing data sources. |
#### Troubleshoot interpolation
You can use a debug section to see what your fields extract and how the URL is interpolated.
Select **Show example log message** to display a text area where you can enter a log message.
{{<figuresrc="/static/img/docs/v75/loki_derived_fields_settings.png"class="docs-image--no-shadow"max-width="800px"caption="Screenshot of the derived fields debugging">}}
You can define and configure the data source in YAML files as part of Grafana's provisioning system.
For more information about provisioning, and for available configuration options, refer to [Provisioning Grafana]({{< relref "../../administration/provisioning/#data-sources" >}}).
#### Provisioning examples
```yaml
apiVersion: 1
datasources:
- name: Loki
type: loki
access: proxy
url: http://localhost:3100
jsonData:
maxLines: 1000
```
**Using basic authorization and a derived field:**
You must escape the dollar (`$`) character in YAML values because it can be used to interpolate environment variables:
```yaml
apiVersion: 1
datasources:
- name: Loki
type: loki
access: proxy
url: http://localhost:3100
basicAuth: true
basicAuthUser: my_user
jsonData:
maxLines: 1000
derivedFields:
# Field with internal link pointing to data source in Grafana.
# Right now, Grafana supports only Jaeger and Zipkin data sources as link targets.
# datasourceUid value can be anything, but it should be unique across all defined data source uids.
- datasourceUid: my_jaeger_uid
matcherRegex: "traceID=(\\w+)"
name: TraceID
# url will be interpreted as query for the datasource
