Grafana Alloy is the new name for our distribution of the OTel collector. Grafana Agent has been deprecated and is in Long-Term Support (LTS) through October 31, 2025. Grafana Agent will reach an End-of-Life (EOL) on November 1, 2025. Read more about why we recommend migrating to Grafana Alloy.
Open source

declare block

declare is an optional configuration block used to define a new [custom component][]. declare blocks must be given a label that determines the name of the custom component.


declare "COMPONENT_NAME" {


The declare block has no predefined schema for its arguments. The body of the declare block is used as the component definition. The body can contain the following:

The declare block may not contain any configuration blocks that aren’t listed above.

Exported fields

The declare block has no predefined schema for its exports. The fields exported by the declare block are determined by the export blocks found in its definition.


This example creates and uses a custom component that self-collects process metrics and forwards them to an argument specified by the user of the custom component:

declare "self_collect" {
  argument "metrics_output" {
    optional = false
    comment  = "Where to send collected metrics."

  prometheus.scrape "selfmonitor" {
    targets = [{
      __address__ = "",

    forward_to = [argument.metrics_output.value]

self_collect "example" {
  metrics_output = prometheus.remote_write.example.receiver

prometheus.remote_write "example" {
  endpoint {