---
title: "Use Grafana Alloy to send metrics to Prometheus | Grafana Alloy documentation"
description: "Learn how to send metrics to Prometheus"
---

# Use Grafana Alloy to send metrics to Prometheus

In the [previous tutorial](../send-logs-to-loki/), you learned how to configure Alloy to collect and process logs from your local machine and send them to Loki.

This tutorial shows you how to configure Alloy to collect and process metrics from your local machine, send them to Prometheus, and use Grafana to explore the results.

## Before you begin

To complete this tutorial:

- You must have a basic understanding of Alloy and telemetry collection in general.
- You should be familiar with Prometheus, PromQL, Loki, LogQL, and basic Grafana navigation.
- You must complete the [previous tutorial](../send-logs-to-loki/) to prepare the following prerequisites:
  
  - Install Alloy and start the service in your environment.
  - Set up a local Grafana instance.
  - Create a `config.alloy` file.

> Tip
> 
> Alternatively, you can try out this example in the interactive learning environment: [Sending metrics to Prometheus](https://killercoda.com/grafana-labs/course/alloy/send-metrics-to-prometheus).
> 
> It’s a fully configured environment with all the dependencies already installed.

## Configure Alloy

In this tutorial, you configure Alloy to collect metrics and send them to Prometheus.

You add components to your `config.alloy` file to tell Alloy which metrics you want to scrape, how you want to process that data, and where you want the data sent.

The following steps build on the `config.alloy` file you created in the previous tutorial.

### First component: Scraping

Paste the following component configuration at the top of your `config.alloy` file:

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
prometheus.exporter.unix "local_system" { }

prometheus.scrape "scrape_metrics" {
  targets         = prometheus.exporter.unix.local_system.targets
  forward_to      = [prometheus.relabel.filter_metrics.receiver]
  scrape_interval = "10s"
}
```

This configuration creates a [`prometheus.scrape`](../../reference/components/prometheus/prometheus.scrape/) component named `scrape_metrics` which does the following:

- It connects to the `local_system` component as its source or target.
- It forwards the metrics it scrapes to the receiver of another component called `filter_metrics`.
- It tells Alloy to scrape metrics every 10 seconds.

### Second component: Filter metrics

Filtering non-essential metrics before sending them to a data source can help you reduce costs and allow you to focus on the data that matters most.

The following example demonstrates how you can filter out or drop metrics before sending them to Prometheus.

Paste the following component configuration below the previous component in your `config.alloy` file:

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
prometheus.relabel "filter_metrics" {
  rule {
    action        = "drop"
    source_labels = ["env"]
    regex         = "dev"
  }

  forward_to = [prometheus.remote_write.metrics_service.receiver]
}
```

The [`prometheus.relabel`](../../reference/components/prometheus/prometheus.relabel/) component is commonly used to filter Prometheus metrics or standardize the label set passed to one or more downstream receivers. You can use this component to rewrite the label set of each metric sent to the receiver. Within this component, you can define rule blocks to specify how you would like to process metrics before they’re stored or forwarded.

This configuration creates a [`prometheus.relabel`](../../reference/components/prometheus/prometheus.relabel/) component named `filter_metrics` which does the following:

- It receives scraped metrics from the `scrape_metrics` component.
- It tells Alloy to drop metrics that have an `"env"` label equal to `"dev"`.
- It forwards the processed metrics to the receiver of another component called `metrics_service`.

### Third component: Write metrics to Prometheus

> Note
> 
> Prometheus typically scrapes metrics from targets using a pull mechanism. This component pushes metrics to Prometheus using the remote write protocol. To accept these remote write requests, start Prometheus with the `--web.enable-remote-write-receiver` flag. For more information, refer to the [Remote storage integrations](https://prometheus.io/docs/prometheus/latest/storage/#overview) topic in the Prometheus documentation.

Paste the following component configuration below the previous component in your `config.alloy` file:

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
prometheus.remote_write "metrics_service" {
    endpoint {
        url = "http://localhost:9090/api/v1/write"

        // basic_auth {
        //   username = "admin"
        //   password = "admin"
        // }
    }
}
```

This final component creates a [`prometheus.remote_write`](../../reference/components/prometheus/prometheus.remote_write/) component named `metrics_service` that points to `http://localhost:9090/api/v1/write`.

This completes the simple configuration pipeline.

> Tip
> 
> The `basic_auth` is commented out because the local `docker compose` stack doesn’t require it. It’s included in this example to show how you can configure authorization for other environments.
> 
> For further authorization options, refer to the [`prometheus.remote_write`](../../reference/components/prometheus/prometheus.remote_write/) component documentation.

This connects directly to the Prometheus instance running in the Docker container.

## Reload the configuration

Copy your local `config.alloy` file into the default Alloy configuration file location.

macos linux

![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

macos ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```macos
sudo cp config.alloy $(brew --prefix)/etc/alloy/config.alloy
```

linux ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```linux
sudo cp config.alloy /etc/alloy/config.alloy
```

Call the `/-/reload` endpoint to tell Alloy to reload the configuration file without a system service restart.

Bash ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```bash
curl -X POST http://localhost:12345/-/reload
```

> Tip
> 
> This step uses the Alloy UI, on `localhost` port `12345`. If you choose to run Alloy in a Docker container, make sure you use the `--server.http.listen-addr=0.0.0.0:12345` argument.
> 
> If you don’t use this argument, the [debugging UI](../../troubleshoot/debug/#alloy-ui) won’t be available outside of the Docker container.

Optional: You can do a system service restart Alloy and load the configuration file:

macos linux

![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

macos ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```macos
brew services restart grafana/grafana/alloy
```

linux ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```linux
sudo systemctl reload alloy
```

## Inspect your configuration in the Alloy UI

Open [http://localhost:12345](http://localhost:12345) and click the **Graph** tab at the top. The graph should look similar to the following:

[](/media/docs/alloy/tutorial/Metrics-inspect-your-config.png)

The Alloy UI shows you a visual representation of the pipeline you built with your Alloy component configuration.

You can see that the components are healthy, and you are ready to explore the metrics in Grafana.

## Log into Grafana and explore metrics in Prometheus

Open [http://localhost:3000/explore/metrics/](http://localhost:3000/explore/metrics/) to access the **Metrics Drilldown** feature in Grafana.

From here you can visually explore the metrics sent to Prometheus by Alloy.

[](/media/docs/alloy/explore-metrics.png)

You can also build PromQL queries manually to explore the data further.

Open [http://localhost:3000/explore](http://localhost:3000/explore) to access the **Explore** feature in Grafana.

Select Prometheus as the data source and click the **Metrics Browser** button to select the metric, labels, and values for your labels.

Here you can see that metrics are flowing through to Prometheus as expected, and the end-to-end configuration was successful.

## Summary

You have configured Alloy to collect and process metrics from your local host and send them to your local Grafana stack.