Documentationbreadcrumb arrow breadcrumb arrow Grafana Alloybreadcrumb arrow Referencebreadcrumb arrow Componentsbreadcrumb arrow otelcolbreadcrumb arrow otelcol.receiver.prometheus
Public preview Open source

otelcol.receiver.prometheus

Public preview: This is a public preview component. Public preview components are subject to breaking changes, and may be replaced with equivalent functionality that cover the same use case. To enable and use a public preview component, you must set the stability.level flag to public-preview or below.

otelcol.receiver.prometheus receives Prometheus metrics, converts them to the OpenTelemetry metrics format, and forwards them to other otelcol.* components.

You can specify multiple otelcol.receiver.prometheus components by giving them different labels.

Note

otelcol.receiver.prometheus is a custom component built on a fork of the upstream OpenTelemetry receiver.

Note

In Alloy v1.14.0, otelcol.receiver.prometheus no longer sets OTLP metric start times for Prometheus metrics. The receiver forwards metrics without adding start times when the Prometheus input does not have a created time.

Start time is a way to tell when a cumulative metric such as an OTLP “sum” or a Prometheus “counter” was last reset. If your database uses start times for OTLP metrics, you can use otelcol.processor.metric_start_time to set it. Grafana Mimir’s OTLP endpoint and Grafana Cloud’s OTLP Gateway both support OTLP metric start time.

To add the start time in the same way that otelcol.receiver.prometheus did it prior to Alloy v1.14.0, configure otelcol.processor.metric_start_time with strategy set to true_reset_point.

In practice it is only necessary to use true_reset_point if your Mimir/Grafana Cloud instance is explicitly configured with a -distributor.otel-created-timestamp-zero-ingestion-enabled=true flag, since true_reset_point will send a sample with the same start and end time and Mimir by default won’t create a zero sample for it. For most Mimir and Grafana Cloud use cases there would be no change in behaviour even if no otelcol.processor.metric_start_time is added.

Usage

Alloy 
otelcol.receiver.prometheus "<LABEL>" {
  output {
    metrics = [...]
  }
}

Arguments

The otelcol.receiver.prometheus component doesn’t support any arguments. You can configure this component with blocks.

Blocks

You can use the following block with otelcol.receiver.prometheus:

BlockDescriptionRequired
outputConfigures where to send received telemetry data.yes

output

Required

The output block configures a set of components to forward resulting telemetry data to.

The following arguments are supported:

NameTypeDescriptionDefaultRequired
logslist(otelcol.Consumer)List of consumers to send logs to.[]no
metricslist(otelcol.Consumer)List of consumers to send metrics to.[]no
traceslist(otelcol.Consumer)List of consumers to send traces to.[]no

You must specify the output block, but all its arguments are optional. By default, telemetry data is dropped. Configure the metrics, logs, and traces arguments accordingly to send telemetry data to other components.

Exported fields

The following fields are exported and can be referenced by other components:

NameTypeDescription
receiverMetricsReceiverA value that other components can use to send Prometheus metrics to.

Component health

otelcol.receiver.prometheus is only reported as unhealthy if given an invalid configuration.

Debug information

otelcol.receiver.prometheus doesn’t expose any component-specific debug information.

Example

This example uses the otelcol.receiver.prometheus component as a bridge between the Prometheus and OpenTelemetry ecosystems. The component exposes a receiver which the prometheus.scrape component uses to send Prometheus metric data to. The metrics are converted to the OTLP format before they’re forwarded to the otelcol.exporter.otlp component to be sent to an OTLP-capable endpoint:

Alloy 
prometheus.scrape "default" {
    // Collect metrics from the default HTTP listen address.
    targets = [{"__address__"   = "127.0.0.1:12345"}]

    forward_to = [otelcol.receiver.prometheus.default.receiver]
}

otelcol.receiver.prometheus "default" {
  output {
    metrics = [otelcol.exporter.otlp.default.input]
  }
}

otelcol.exporter.otlp "default" {
  client {
    endpoint = sys.env("OTLP_ENDPOINT")
  }
}

Compatible components

otelcol.receiver.prometheus can accept arguments from the following components:

otelcol.receiver.prometheus has exports that can be consumed by the following components:

Note

Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.