Documentation Grafana Cloud Instrument and send data Grafana Alloy Reference Components prometheus prometheus.receive_http

prometheus.receive_http

prometheus.receive_http listens for HTTP requests containing Prometheus metric samples and forwards them to other components capable of receiving metrics.

The HTTP API exposed is compatible with Prometheus remote_write API. This means that other prometheus.remote_write components can be used as a client and send requests to prometheus.receive_http which enables using Alloy as a proxy for Prometheus metrics.

Usage

alloy Copy

prometheus.receive_http "LABEL" {
  http {
    listen_address = "LISTEN_ADDRESS"
    listen_port = PORT
  }
  forward_to = RECEIVER_LIST
}

The component will start an HTTP server supporting the following endpoint:

• POST /api/v1/metrics/write - send metrics to the component, which in turn will be forwarded to the receivers as configured in forward_to argument. The request format must match that of Prometheus remote_write API. One way to send valid requests to this component is to use another Alloy with a prometheus.remote_write component.

Arguments

prometheus.receive_http supports the following arguments:

Blocks

The following blocks are supported inside the definition of prometheus.receive_http:

http

The http block configures the HTTP server.

You can use the following arguments to configure the http block. Any omitted fields take their default values.

Exported fields

prometheus.receive_http does not export any fields.

Component health

prometheus.receive_http is reported as unhealthy if it is given an invalid configuration.

Debug metrics

The following are some of the metrics that are exposed when this component is used. Note that the metrics include labels such as status_code where relevant, which can be used to measure request success rates.

• prometheus_receive_http_request_duration_seconds (histogram): Time (in seconds) spent serving HTTP requests.
• prometheus_receive_http_request_message_bytes (histogram): Size (in bytes) of messages received in the request.
• prometheus_receive_http_response_message_bytes (histogram): Size (in bytes) of messages sent in response.
• prometheus_receive_http_tcp_connections (gauge): Current number of accepted TCP connections.
• prometheus_fanout_latency (histogram): Write latency for sending metrics to other components.
• prometheus_forwarded_samples_total (counter): Total number of samples sent to downstream components.

Example

Receiving metrics over HTTP

This example creates a prometheus.receive_http component which starts an HTTP server listening on 0.0.0.0 and port 9999. The server receives metrics and forwards them to a prometheus.remote_write component which writes these metrics to the specified HTTP endpoint.

alloy Copy

// Receives metrics over HTTP
prometheus.receive_http "api" {
  http {
    listen_address = "0.0.0.0"
    listen_port = 9999
  }
  forward_to = [prometheus.remote_write.local.receiver]
}

// Send metrics to a locally running Mimir.
prometheus.remote_write "local" {
  endpoint {
    url = "http://mimir:9009/api/v1/push"

    basic_auth {
      username = "example-user"
      password = "example-password"
    }
  }
}

Proxying metrics

In order to send metrics to the prometheus.receive_http component defined in the previous example, another Alloy can run with the following configuration:

alloy Copy

// Collects metrics of localhost:12345
prometheus.scrape "self" {
  targets = [
    {"__address__" = "localhost:12345", "job" = "alloy"},
  ]
  forward_to = [prometheus.remote_write.local.receiver]
}

// Writes metrics to localhost:9999/api/v1/metrics/write - e.g. served by
// the prometheus.receive_http component from the example above.
prometheus.remote_write "local" {
  endpoint {
    url = "http://localhost:9999/api/v1/metrics/write"
  }
}

Technical details

prometheus.receive_http uses snappy for compression.

Compatible components

prometheus.receive_http can accept arguments from the following components:

• Components that export Prometheus MetricsReceiver