Caution
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.
Configuration language concepts
The Grafana Agent Flow configuration language refers to the language used in configuration files which define and configure components to run.
The configuration language is called River, a Terraform/HCL-inspired language:
prometheus.scrape "default" {
targets = [{
"__address__" = "demo.robustperception.io:9090",
}]
forward_to = [prometheus.remote_write.default.receiver]
}
prometheus.remote_write "default" {
endpoint {
url = "http://localhost:9009/api/prom/push"
}
}
River was designed with the following requirements in mind:
- Fast: The configuration language must be fast so the component controller can evaluate changes as quickly as possible.
- Simple: The configuration language must be easy to read and write to minimize the learning curve.
- Debuggable: The configuration language must give detailed information when there’s a mistake in the config file.
Attributes
Attributes are used to configure individual settings. They always take the
form of ATTRIBUTE_NAME = ATTRIBUTE_VALUE
.
log_level = "debug"
This sets the log_level
attribute to "debug"
.
Expressions
Expressions are used to compute the value of an attribute. The simplest
expressions are constant values like "debug"
, 32
, or [1, 2, 3, 4]
. River
supports more complex expressions, such as:
- Referencing the exports of components:
local.file.password_file.content
- Mathematical operations:
1 + 2
,3 * 4
,(5 * 6) + (7 + 8)
- Equality checks:
local.file.file_a.content == local.file.file_b.content
- Calling functions from River’s standard library:
env("HOME")
(retrieve the value of theHOME
environment variable)
Expressions may be used for any attribute inside a component definition.
Referencing component exports
The most common expression is to reference the exports of a component like
local.file.password_file.content
. A reference to a component’s exports is
formed by merging the component’s name (e.g., local.file
), label (e.g.,
password_file
), and export name (e.g., content
), delimited by period.
For components that don’t use labels, like
prometheus.exporter.unix
, only combine the component name with
export name: prometheus.exporter.unix.targets
.
Blocks
Blocks are used to configure components and groups of attributes. Each block can contain any number of attributes or nested blocks.
prometheus.remote_write "default" {
endpoint {
url = "http://localhost:9009/api/prom/push"
}
}
This file has two blocks:
prometheus.remote_write "default"
: A labeled block which instantiates aprometheus.remote_write
component. The label is the string"default"
.endpoint
: An unlabeled block inside the component which configures an endpoint to send metrics to. This block sets theurl
attribute to specify what the endpoint is.
More information
River is documented in detail in Configuration language section of the Grafana Agent Flow docs.