Documentation Grafana Alloy Reference Components otelcol otelcol.auth.headers

otelcol.auth.headers

otelcol.auth.headers exposes a handler that other otelcol components can use to authenticate requests using custom headers.

This component only supports client authentication.

You can specify multiple otelcol.auth.headers components by giving them different labels.

Usage

alloy Copy

otelcol.auth.headers "<LABEL>" {
  header {
    key   = "<HEADER_NAME>"
    value = "<HEADER_VALUE>"
  }
}

Arguments

otelcol.auth.headers doesn’t support any arguments.

Blocks

You can use the following blocks with otelcol.auth.headers:

debug_metrics

The debug_metrics block configures the metrics that this component generates to monitor its state.

The following arguments are supported:

disable_high_cardinality_metrics is the Alloy equivalent to the telemetry.disableHighCardinalityMetrics feature gate in the OpenTelemetry Collector. It removes attributes that could cause high cardinality metrics. For example, attributes with IP addresses and port numbers in metrics about HTTP and gRPC connections are removed.

header

The header block defines a custom header to attach to requests. It’s valid to provide multiple header blocks to set more than one header.

The supported values for action are:

• insert: Inserts the new header if it doesn’t exist.
• update: Updates the header value if it exists.
• upsert: Inserts a header if it doesn’t exist and updates the header if it exists.
• delete: Deletes the header.

Exactly one of value, from_context, or from_attribute must be provided for each header block.

The value attribute sets the value of the header directly. Alternatively, you can use from_context to dynamically retrieve the header value from request metadata, or you can use from_attribute to dynamically retrieve the header value from request authentication metadata.

For from_context to work, other components in the pipeline also need to be configured appropriately:

• If an otelcol.processor.batch is present in the pipeline, it must be configured to preserve client metadata. Do this by adding the value that from_context needs to the metadata_keys of the batch processor.
• otelcol receivers must be configured with include_metadata set to true so that metadata keys are available to the pipeline.

from_attribute metadata can’t, at this time, be preserved through an otelcol.processor.batch component, and is only provided from the otelcol.auth.basic extension.

Exported fields

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

Component health

otelcol.auth.headers is only reported as unhealthy if given an invalid configuration.

Debug information

otelcol.auth.headers doesn’t expose any component-specific debug information.

Example

This example configures otelcol.exporter.otlp to use custom headers:

alloy Copy

otelcol.receiver.otlp "default" {
  http {
    include_metadata = true
  }
  grpc {
    include_metadata = true
  }

  output {
    metrics = [otelcol.processor.batch.default.input]
    logs    = [otelcol.processor.batch.default.input]
    traces  = [otelcol.processor.batch.default.input]
  }
}

otelcol.processor.batch "default" {
  // Preserve the tenant_id metadata.
  metadata_keys = ["tenant_id"]

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

otelcol.auth.headers "creds" {
  header {
    key          = "X-Scope-OrgID"
    from_context = "tenant_id"
  }

  header {
    key   = "User-ID"
    value = "user_id"
  }
}

otelcol.exporter.otlp "production" {
  client {
    endpoint = sys.env("<OTLP_SERVER_ENDPOINT>")
    auth     = otelcol.auth.headers.creds.handler
  }
}