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.

Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

Open source

argument block

argument is an optional configuration block used to specify parameterized input to a Module. argument blocks must be given a label which determines the name of the argument.

The argument block may not be specified in the main configuration file given to Grafana Agent Flow.


argument "ARGUMENT_NAME" {}


NOTE: For clarity, “argument” in this section refers to arguments which can be given to the argument block. “Module argument” refers to the argument being defined for a module, determined by the label of the argument block.

The following arguments are supported:

optionalboolWhether the argument may be omitted.falseno
commentstringDescription for the argument.falseno
defaultanyDefault value for the argument.nullno

By default, all module arguments are required. The optional argument can be used to mark the module argument as optional. When optional is true, the initial value for the module argument is specified by default.

Exported fields

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

valueanyThe current value of the argument.

The module loader is responsible for determining the values for arguments. Components in a module may use argument.ARGUMENT_NAME.value to retrieve the value provided by the module loader.


This example creates a module where agent metrics are collected. Collected metrics are then forwarded to the argument specified by the loader:

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

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

  forward_to = [argument.metrics_output.value]