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Documentation Grafana Agent Flow mode Reference Components reference otelcol.connector.spanmetrics

otelcol.connector.spanmetrics

otelcol.connector.spanmetrics accepts span data from other otelcol components and aggregates Request, Error and Duration (R.E.D) OpenTelemetry metrics from the spans:

• Request counts are computed as the number of spans seen per unique set of dimensions, including Errors. Multiple metrics can be aggregated if, for instance, a user wishes to view call counts just on service.name and span.name.

• Error counts are computed from the Request counts which have an Error status code metric dimension.

• Duration is computed from the difference between the span start and end times and inserted into the relevant duration histogram time bucket for each unique set dimensions.

NOTE: otelcol.connector.spanmetrics is a wrapper over the upstream OpenTelemetry Collector spanmetrics connector. Bug reports or feature requests will be redirected to the upstream repository, if necessary.

Multiple otelcol.connector.spanmetrics components can be specified by giving them different labels.

Usage

Alloy Copy

otelcol.connector.spanmetrics "LABEL" {
  histogram {
    ...
  }

  output {
    metrics = [...]
  }
}

Arguments

otelcol.connector.spanmetrics supports the following arguments:

Adjusting dimensions_cache_size can improve the Agent process’ memory usage.

The supported values for aggregation_temporality are:

• "CUMULATIVE": The metrics will not be reset after they are flushed.
• "DELTA": The metrics will be reset after they are flushed.

If namespace is set, the generated metric name will be added a namespace. prefix.

Blocks

The following blocks are supported inside the definition of otelcol.connector.spanmetrics:

It is necessary to specify either a “exponential” or an “explicit” block:

• Specifying both an “exponential” and an “explicit” block is not allowed.
• Specifying neither an “exponential” nor an “explicit” block is not allowed.

dimension block

The dimension block configures dimensions to be added in addition to the default ones.

The default dimensions are:

• service.name
• span.name
• span.kind
• status.code

The default dimensions are always added. If no additional dimensions are specified, only the default ones will be added.

The following attributes are supported:

otelcol.connector.spanmetrics will look for the name attribute in the span’s collection of attributes. If it is not found, the resource attributes will be checked.

If the attribute is missing in both the span and resource attributes:

• If default is not set, the dimension will be omitted.
• If default is set, the dimension will be added and its value will be set to the value of default.

histogram block

The histogram block configures the histogram derived from spans’ durations.

The following attributes are supported:

The supported values for unit are:

• "ms": milliseconds
• "s": seconds

exponential block

The exponential block configures a histogram with exponential buckets.

The following attributes are supported:

explicit block

The explicit block configures a histogram with explicit buckets.

The following attributes are supported:

exemplars block

The exemplars block configures how to attach exemplars to histograms.

The following attributes are supported:

output block

Exported fields

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

input accepts otelcol.Consumer traces telemetry data. It does not accept metrics and logs.

Component health

otelcol.connector.spanmetrics is only reported as unhealthy if given an invalid configuration.

Debug information

otelcol.connector.spanmetrics does not expose any component-specific debug information.

Examples

Explicit histogram and extra dimensions

In the example below, http.status_code and http.method are additional dimensions on top of:

• service.name
• span.name
• span.kind
• status.code

Alloy Copy

otelcol.receiver.otlp "default" {
  http {}
  grpc {}

  output {
    traces  = [otelcol.connector.spanmetrics.default.input]
  }
}

otelcol.connector.spanmetrics "default" {
  // Since a default is not provided, the http.status_code dimension will be omitted
  // if the span does not contain http.status_code.
  dimension {
    name = "http.status_code"
  }

  // If the span is missing http.method, the connector will insert
  // the http.method dimension with value 'GET'.
  dimension {
    name = "http.method"
    default = "GET"
  }

  dimensions_cache_size = 333

  aggregation_temporality = "DELTA"

  histogram {
    unit = "s"
    explicit {
      buckets = ["333ms", "777s", "999h"]
    }
  }

  // The period on which all metrics (whose dimension keys remain in cache) will be emitted.
  metrics_flush_interval = "33s"

  namespace = "test.namespace"

  output {
    metrics = [otelcol.exporter.otlp.production.input]
  }
}

otelcol.exporter.otlp "production" {
  client {
    endpoint = env("OTLP_SERVER_ENDPOINT")
  }
}

Sending metrics via a Prometheus remote write

In order for a target_info metric to be generated, the incoming spans resource scope attributes must contain service.name and service.instance.id attributes.

The target_info metric will be generated for each resource scope, while OpenTelemetry metric names and attributes will be normalized to be compliant with Prometheus naming rules.

Alloy Copy

otelcol.receiver.otlp "default" {
  http {}
  grpc {}

  output {
    traces  = [otelcol.connector.spanmetrics.default.input]
  }
}

otelcol.connector.spanmetrics "default" {
  histogram {
    exponential {}
  }

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

otelcol.exporter.prometheus "default" {
  forward_to = [prometheus.remote_write.mimir.receiver]
}

prometheus.remote_write "mimir" {
  endpoint {
    url = "http://mimir:9009/api/v1/push"
  }
}

Compatible components

otelcol.connector.spanmetrics can accept arguments from the following components:

• Components that export OpenTelemetry otelcol.Consumer

otelcol.connector.spanmetrics has exports that can be consumed by the following components:

• Components that consume OpenTelemetry otelcol.Consumer