Using Loki in Grafana

    Add it as a data source and you are ready to build dashboards or query your log data in Explore. Refer to for instructions on how to add a data source to Grafana. Only users with the organization admin role can add data sources.

    To access Loki settings, click the Configuration (gear) icon, then click Data Sources, and then click the Loki data source.

    The Derived Fields configuration allows you to:

    • Add fields parsed from the log message.

    You can use this functionality to link to your tracing backend directly from your logs, or link to a user profile page if a userId is present in the log line. These links appear in the log details.

    Each derived field consists of:

    • Name - Shown in the log details as a label.
    • Regex - A Regex pattern that runs on the log message and captures part of it as the value of the new field. Can only contain a single capture group.
    • URL/query - If the link is external, then enter the full link URL. If the link is internal link, then this input serves as query for the target data source. In both cases, you can interpolate the value from the field with ${__value.raw } macro.
    • Internal link - Select if the link is internal or external. In case of internal link, a data source selector allows you to select the target data source. Only tracing data sources are supported.

    You can use a debug section to see what your fields extract and how the URL is interpolated. Click Show example log message to show the text area where you can enter a log message.

    The new field with the link shown in log details:

    Detected fields link in Explore

    Loki query editor

    With Loki log browser you can easily navigate trough your list of labels and values and construct the query of your choice. Log browser has multi-step selection:

    1. Choose the labels you would like to consider for your search.
    2. Pick the values for selected labels. Log browser supports facetting and therefore it shows you only possible label combinations.
    3. Choose the type of query - logs query or rate metrics query. Additionally, you can also validate selector.

    There are two types of LogQL queries:

    • Log queries - Return the contents of log lines.
    • Metric queries - Extend log queries and calculate sample values based on the content of logs from a log query.

    Querying and displaying log data from Loki is available via Explore, and with the in dashboards. Select the Loki data source, and then enter a LogQL query to display your logs.

    A log query consists of two parts: log stream selector, and a log pipeline. For performance reasons begin by choosing a log stream by selecting a log label.

    When using a search expression as detailed above, you can retrieve the context surrounding your filtered results. By clicking the Show Context link on the filtered rows, you’ll be able to investigate the log messages that came before and after the log message you’re interested in.

    Loki supports Live tailing which displays logs in real-time. This feature is supported in .

    Note that Live Tailing relies on two Websocket connections: one between the browser and the Grafana server, and another between the Grafana server and the Loki server. If you run any reverse proxies, please configure them accordingly. The following example for Apache2 can be used for proxying between the browser and the Grafana server:

    The following example shows basic NGINX proxy configuration. It assumes that the Grafana server is available at , Loki server is running locally without proxy, and your external site uses HTTPS. If you also host Loki behind NGINX proxy, then you might want to repeat the following configuration for Loki as well.

    In the http section of NGINX configuration, add the following map definition:

    1.   map $http_upgrade $connection_upgrade {
    2.     default upgrade;
    3.     '' close;
    4.   }

    Note: This feature is only available in Grafana v6.3+.

    Metric queries

    LogQL supports wrapping a log query with functions that allow for creating metrics out of the logs. See documentation on how to create and use metrics queries.

    Instead of hard-coding things like server, application and sensor name in your metric queries, you can use variables in their place. Variables are shown as drop-down select boxes at the top of the dashboard. These drop-down boxes make it easy to change the data being displayed in your dashboard.

    Check out the documentation for an introduction to the templating feature and the different types of template variables.

    Query variable

    Variable of the type Query allows you to query Loki for a list labels or label values. The Loki data source plugin provides the following functions you can use in the Query input field.

    You can use any non-metric Loki query as a source for annotations. Log content will be used as annotation text and your log stream labels as tags, so there is no need for additional mapping.

    Configure the data source with provisioning

    You can set up the data source via config files with Grafana’s provisioning system. You can read more about how it works and all the settings you can set for data sources on the provisioning docs page

    Here is an example:

    1. apiVersion: 1
    2. datasources:
    4.     type: loki
    5.     access: proxy
    6.     url: http://localhost:3100
    7.     jsonData:
    8.       maxLines: 1000

    Here’s another with basic auth and derived field. Keep in mind that $ character needs to be escaped in YAML values as it is used to interpolate environment variables:

    Here’s an example of a Jaeger data source corresponding to the above example. Note that the Jaeger uid value does match the Loki datasourceUid value.

    1. datasources:
    2.     - name: Jaeger
    3.       type: jaeger
    4.       url: http://jaeger-tracing-query:16686/
    5.       access: proxy
    7.       uid: my_jaeger_uid