Documentation Grafana Cloud Instrument and send data Grafana Alloy Reference Components otelcol otelcol.processor.discovery

otelcol.processor.discovery

otelcol.processor.discovery accepts traces telemetry data from other otelcol components. It can be paired with discovery.* components, which supply a list of labels for each discovered target. otelcol.processor.discovery adds resource attributes to spans which have a hostname matching the one in the __address__ label provided by the discovery.* component.

Multiple otelcol.processor.discovery components can be specified by giving them different labels.

Usage

alloy Copy

otelcol.processor.discovery "LABEL" {
  targets = [...]
  output {
    traces  = [...]
  }
}

Arguments

otelcol.processor.discovery supports the following arguments:

targets could come from discovery.* components:

1. The __address__ label will be matched against the IP address of incoming spans.
   • If __address__ contains a port, it is ignored.
2. If a match is found, then relabeling rules are applied.
   • Note that labels starting with __ will not be added to the spans.

The supported values for operation_type are:

• insert: Inserts a new resource attribute if the key does not already exist.
• update: Updates a resource attribute if the key already exists.
• upsert: Either inserts a new resource attribute if the key does not already exist, or updates a resource attribute if the key does exist.

The supported values for pod_associations are:

• ip: The hostname will be sourced from an ip resource attribute.
• net.host.ip: The hostname will be sourced from a net.host.ip resource attribute.
• k8s.pod.ip: The hostname will be sourced from a k8s.pod.ip resource attribute.
• hostname: The hostname will be sourced from a host.name resource attribute.
• connection: The hostname will be sourced from the context from the incoming requests (gRPC and HTTP).

If multiple pod_associations methods are enabled, the order of evaluation is honored. For example, when pod_associations is ["ip", "net.host.ip"], "net.host.ip" may be matched only if "ip" hasn’t already matched.

Blocks

The following blocks are supported inside the definition of otelcol.processor.discovery:

output block

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

The following arguments are supported:

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

Exported fields

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

input accepts otelcol.Consumer OTLP-formatted data for telemetry signals of these types:

• traces

Component health

otelcol.processor.discovery is only reported as unhealthy if given an invalid configuration.

Debug information

otelcol.processor.discovery doesn’t expose any component-specific debug information.

Examples

Basic usage

alloy Copy

discovery.http "dynamic_targets" {
    url              = "https://example.com/scrape_targets"
    refresh_interval = "15s"
}

otelcol.processor.discovery "default" {
    targets = discovery.http.dynamic_targets.targets

    output {
        traces = [otelcol.exporter.otlp.default.input]
    }
}

Using more than one discovery process

Outputs from more than one discovery process can be combined via the array.concat function.

alloy Copy

discovery.http "dynamic_targets" {
    url              = "https://example.com/scrape_targets"
    refresh_interval = "15s"
}

discovery.kubelet "k8s_pods" {
  bearer_token_file = "/var/run/secrets/kubernetes.io/serviceaccount/token"
  namespaces        = ["default", "kube-system"]
}

otelcol.processor.discovery "default" {
    targets = array.concat(discovery.http.dynamic_targets.targets, discovery.kubelet.k8s_pods.targets)

    output {
        traces = [otelcol.exporter.otlp.default.input]
    }
}

Using a preconfigured list of attributes

It’s not necessary to use a discovery component. In the example below, both a test_label and a test.label.with.dots resource attributes will be added to a span if its IP address is “1.2.2.2”. The __internal_label__ will be not be added to the span, because it begins with a double underscore (__).

alloy Copy

otelcol.processor.discovery "default" {
    targets = [{
        "__address__"          = "1.2.2.2",
        "__internal_label__"   = "test_val",
        "test_label"           = "test_val2",
        "test.label.with.dots" = "test.val2.with.dots"}]

    output {
        traces = [otelcol.exporter.otlp.default.input]
    }
}

Compatible components

otelcol.processor.discovery can accept arguments from the following components:

• Components that export Targets
• Components that export OpenTelemetry otelcol.Consumer

otelcol.processor.discovery has exports that can be consumed by the following components:

• Components that consume OpenTelemetry otelcol.Consumer