Prometheus data source

Grafana includes built-in support for Prometheus. This topic explains options, variables, querying, and other options specific to the Prometheus data source. Refer to Add a data source for instructions on how to add a data source to Grafana. Only users with the organization admin role can add data sources.

Note: You can use Grafana Cloud to avoid the overhead of installing, maintaining, and scaling your observability stack. The free forever plan includes Grafana, 10K Prometheus series, 50 GB logs, and more.Create a free account to get started.

Prometheus settings

To access Prometheus settings, hover your mouse over the Configuration (gear) icon, then click Data Sources, and then click the Prometheus data source.

NameDescription
NameThe data source name. This is how you refer to the data source in panels and queries.
DefaultDefault data source that is pre-selected for new panels.
UrlThe URL of your Prometheus server, for example, http://prometheus.example.org:9090.
AccessServer (default) = URL needs to be accessible from the Grafana backend/server, Browser = URL needs to be accessible from the browser. Note: Browser (direct) access is deprecated and will be removed in a future release.
Basic AuthEnable basic authentication to the Prometheus data source.
UserUser name for basic authentication.
PasswordPassword for basic authentication.
Scrape intervalSet this to the typical scrape and evaluation interval configured in Prometheus. Defaults to 15s.
HTTP methodUse either POST or GET HTTP method to query your data source. POST is the recommended and pre-selected method as it allows bigger queries. Change this to GET if you have a Prometheus version older than 2.1 or if POST requests are restricted in your network.
Disable metrics lookupChecking this option will disable the metrics chooser and metric/label support in the query field’s autocomplete. This helps if you have performance issues with bigger Prometheus instances.
Custom Query ParametersAdd custom parameters to the Prometheus query URL. For example timeout, partial_response, dedup, or max_source_resolution. Multiple parameters should be concatenated together with an ‘&’.
Label nameAdd the name of the field in the label object.
URLIf the link is external, then enter the full link URL. You can interpolate the value from the field with ${__value.raw } macro.
Internal linkSelect if the link is internal or external. In the case of an internal link, a data source selector allows you to select the target data source. Supports tracing data sources only.

Prometheus query editor

Below you can find information and options for Prometheus query editor in dashboard and in Explore.

Query editor in dashboards

Open a graph in edit mode by clicking the title > Edit (or by pressing e key while hovering over panel).

Prometheus - 图1 Prometheus - 图2Prometheus - 图3

NameDescription
Query expressionPrometheus query expression. For more information, refer to the Prometheus documentation.
Legend formatControls the name of the time series, using name or pattern. For example, {{hostname}} is replaced by the label value for the label hostname.
StepUse ‘Minimum’ or ‘Maximum’ step mode to set the lower or upper bounds respectively on the interval between data points. For example, set “minimum 1h” to hint that measurements are not frequent (taken hourly). Use the ‘Exact’ step mode to set a precise interval between data points. $interval and $rate_interval are supported.
Resolution1/1 sets both the $interval variable and the step parameter of Prometheus range queries such that each pixel corresponds to one data point. For better performance, you can pick lower resolutions. 1/2 only retrieves a data point for every other pixel, and 1/10 retrieves one data point per 10 pixels. Both Min time interval and Step limit the final value of $interval and step.
Metric lookupSearch for metric names in this input field.
Format asYou can switch between Table Time series or Heatmap options. The Table option works only in the Table panel. Heatmap displays metrics of the Histogram type on a Heatmap panel. Under the hood, it converts cumulative histograms to regular ones and sorts series by the bucket bound.
InstantPerform an “instant” query to return only the latest value that Prometheus has scraped for the requested time series. Instant queries can return results much faster than normal range queries. Use them to look up label sets.
Min time intervalThis value multiplied by the denominator from the Resolution setting sets a lower limit to both the $__interval variable and the step parameter of Prometheus range queries. Defaults to Scrape interval as specified in the data source options.
ExemplarsRun and show exemplars in the graph.

Note: Grafana modifies the request dates for queries to align them with the dynamically calculated step. This ensures consistent display of metrics data, but it can result in a small gap of data at the right edge of a graph.

Instant queries in dashboards

The Prometheus data source allows you to run “instant” queries, which query only the latest value. You can visualize the results in a table panel to see all available labels of a timeseries.

Instant query results are made up only of one data point per series but can be shown in the graph panel with the help of series overrides. To show them in the graph as a latest value point, add a series override and select Points > true. To show a horizontal line across the whole graph, add a series override and select Transform > constant.

Support for constant series overrides is available from Grafana v6.4

Query editor in Explore

NameDescription
Query expressionPrometheus query expression, check out the Prometheus documentation.
StepStep parameter of Prometheus range queries. Time units can be used here, for example: 5s, 1m, 3h, 1d, 1y. Default unit if no unit specified is s (seconds).
Query typeRange, Instant, or Both. When running Range query, the result of the query is displayed in graph and table. Instant query returns only the latest value that Prometheus has scraped for the requested time series and it is displayed in the table. When Both is selected, both instant query and range query is run. Result of range query is displayed in graph and the result of instant query is displayed in the table.
ExemplarsRun and show exemplars in the graph.

Metrics browser

The metrics browser allows you to quickly find metrics and select relevant labels to build basic queries. When you open the browser you will see all available metrics and labels. If supported by your Prometheus instance, each metric will show its HELP and TYPE as a tooltip.

Screenshot of the metrics browser for PrometheusPrometheus - 图5

When you select a metric, the browser narrows down the available labels to show only the ones applicable to the metric. You can then select one or more labels for which the available label values are shown in lists in the bottom section. Select one or more values for each label to tighten your query scope.

Note: If you do not remember a metric name to start with, you can also select a few labels first, to narrow down the list and then find relevant label values.

All lists in the metrics browser have a search field above them to quickly filter for metrics or labels that match a certain string. The values section only has one search field. Its filtering applies to all labels to help you find values across labels once they have been selected, for example, among your labels app, job, job_name only one might with the value you are looking for.

Once you are satisfied with your query, click “Use query” to run the query. The button “Use as rate query” adds a rate(...)[$__interval] around your query to help write queries for counter metrics. The “Validate selector” button will check with Prometheus how many time series are available for that selector.

Limitations

The metrics browser has a hard limit of 10,000 labels (keys) and 50,000 label values (including metric names). If your Prometheus instance returns more results, the browser will continue functioning. However, the result sets will be cut off above those maximum limits.

Templating

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 dropdown select boxes at the top of the dashboard. These dropdowns make it easy to change the data being displayed in your dashboard.

Check out the Templating 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 Prometheus for a list of metrics, labels or label values. The Prometheus data source plugin provides the following functions you can use in the Query input field.

NameDescriptionUsed API endpoints
labelnames()Returns a list of label names./api/v1/labels
labelvalues(label)Returns a list of label values for the label in every metric./api/v1/label/label/values
label_values(metric, label)Returns a list of label values for the label in the specified metric./api/v1/series
metrics(metric)Returns a list of metrics matching the specified metric regex./api/v1/label/__name/values
query_result(query)Returns a list of Prometheus query result for the query./api/v1/query

For details of what metric names, label names and label values are please refer to the Prometheus documentation.

Using interval and range variables

Support for $__range, $__range_s and $__range_ms only available from Grafana v5.3

You can use some global built-in variables in query variables, for example, $__interval, $__interval_ms, $__range, $__range_s and $__range_ms. See Global built-in variables for more information. They are convenient to use in conjunction with the query_result function when you need to filter variable queries since the label_values function doesn’t support queries.

Make sure to set the variable’s refresh trigger to be On Time Range Change to get the correct instances when changing the time range on the dashboard.

Example usage:

Populate a variable with the busiest 5 request instances based on average QPS over the time range shown in the dashboard:

  1. Query: query_result(topk(5, sum(rate(http_requests_total[$__range])) by (instance)))
  2. Regex: /"([^"]+)"/

Populate a variable with the instances having a certain state over the time range shown in the dashboard, using $__range_s:

  1. Query: query_result(max_over_time(<metric>[${__range_s}s]) != <state>)
  2. Regex:

Using $__rate_interval

Note: Available in Grafana 7.2 and above

$__rate_interval is the recommended interval to use in the rate and increase functions. It will “just work” in most cases, avoiding most of the pitfalls that can occur when using a fixed interval or $__interval.

  1. OK: rate(http_requests_total[5m])
  2. Better: rate(http_requests_total[$__rate_interval])

Details: $__rate_interval is defined as max($__interval + Scrape interval, 4 * Scrape interval), where Scrape interval is the Min step setting (AKA queryinterval, a setting per PromQL query) if any is set. Otherwise, the Scrape interval setting in the Prometheus data source is used. (The Min interval setting in the panel is modified by the resolution setting and therefore doesn’t have any effect on _Scrape interval.) This article contains additional details.

Using variables in queries

There are two syntaxes:

  • $<varname> Example: rate(http_requests_total{job=~”$job”}[5m])
  • [[varname]] Example: rate(http_requests_total{job=~”[[job]]“}[5m])

Why two ways? The first syntax is easier to read and write but does not allow you to use a variable in the middle of a word. When the Multi-value or Include all value options are enabled, Grafana converts the labels from plain text to a regex compatible string. Which means you have to use =~ instead of =.

Ad hoc filters variable

Prometheus supports the special ad hoc filters variable type. It allows you to specify any number of label/value filters on the fly. These filters are automatically applied to all your Prometheus queries.

Annotations

Annotations allow you to overlay rich event information on top of graphs. You add annotation queries via the Dashboard menu / Annotations view.

Prometheus supports two ways to query annotations.

The step option is useful to limit the number of events returned from your query.

Get Grafana metrics into Prometheus

Grafana exposes metrics for Prometheus on the /metrics endpoint. We also bundle a dashboard within Grafana so you can get started viewing your metrics faster. You can import the bundled dashboard by going to the data source edit page and click the dashboard tab. There you can find a dashboard for Grafana and one for Prometheus. Import and start viewing all the metrics!

For detailed instructions, refer to Internal Grafana metrics.

Prometheus API

The Prometheus data source works with other projects that implement the Prometheus query API including:

For more information on how to query other Prometheus-compatible projects from Grafana, refer to the specific project documentation.

Provision the Prometheus data source

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

Here are some provisioning examples for this data source:

  1. apiVersion: 1
  2. datasources:
  3. - name: Prometheus
  4. type: prometheus
  5. # Access mode - proxy (server in the UI) or direct (browser in the UI).
  6. access: proxy
  7. url: http://localhost:9090
  8. jsonData:
  9. httpMethod: POST
  10. exemplarTraceIdDestinations:
  11. # Field with internal link pointing to data source in Grafana.
  12. # datasourceUid value can be anything, but it should be unique across all defined data source uids.
  13. - datasourceUid: my_jaeger_uid
  14. name: traceID
  15. # Field with external link.
  16. - name: traceID
  17. url: 'http://localhost:3000/explore?orgId=1&left=%5B%22now-1h%22,%22now%22,%22Jaeger%22,%7B%22query%22:%22$${__value.raw}%22%7D%5D'

Amazon Managed Service for Prometheus

The Prometheus data source works with Amazon Managed Service for Prometheus. If you are using an AWS Identity and Access Management (IAM) policy to control access to your Amazon Managed Service for Prometheus domain, then you must use AWS Signature Version 4 (AWS SigV4) to sign all requests to that domain. For more details on AWS SigV4, refer to the AWS documentation.

Note: Grafana version 7.3.5 or higher is required to use SigV4 authentication.

To connect the Prometheus data source to Amazon Managed Service for Prometheus using SigV4 authentication, refer to the AWS guide to Set up Grafana open source or Grafana Enterprise for use with AMP.

If you are running Grafana in an Amazon EKS cluster, follow the AWS guide to Query using Grafana running in an Amazon EKS cluster.

Configuring exemplars

Note: This feature is available in Prometheus 2.26+ and Grafana 7.4+.

Grafana 7.4 and later versions have the capability to show exemplars data alongside a metric both in Explore and Dashboards. Exemplars are a way to associate higher cardinality metadata from a specific event with traditional timeseries data.

Screenshot showing the detail window of an ExemplarPrometheus - 图7

Configure Exemplars in the data source settings by adding external or internal links.

Screenshot of the Exemplars configurationPrometheus - 图9