> ## Documentation Index
> Fetch the complete documentation index at: https://docs.honeycomb.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Send Application Metrics to Honeycomb

> Instrument your application with OpenTelemetry SDKs to create counters, histograms, and gauges, and send metrics to Honeycomb for analysis.

## How It Works

OpenTelemetry SDKs are implemented and stable for several languages.
They provide an API, which allows your application to create custom metrics with **metrics instruments** like counters, histograms, and gauges.
Instrumentation libraries used in different languages can also capture metrics from the application's runtime environment, such as the number of HTTP requests served by an HTTP server.
OpenTelemetry SDKs can then be configured to send metrics to Honeycomb over OpenTelemetry Protocol (OTLP).

```mermaid actions={false} theme={}
flowchart LR
  subgraph S["Instrumented App"]
    A("OpenTelemetry SDK")
  end
  A -->|OTLP| B("Honeycomb")
```

## Instrumenting Your Application

Refer to the [OpenTelemetry SDK Documentation for your environment](https://opentelemetry.io/status/) for details on how to instrument your application.
You will need to enable an OTLP exporter and it should have:

* a destination of:
  * for our US instance: `api.honeycomb.io:443`
  * for our EU instance: `api.eu1.honeycomb.io:443`
* an `x-honeycomb-team` header with an API key that has write permissions

With the current metrics experience, Honeycomb routes all of your metrics to a managed metrics dataset (named `Metrics`) automatically, so you do not need to specify a dataset.

<Note>
  The `x-honeycomb-dataset` header applied to the legacy metrics experience, where it named the dataset metrics were sent to. It is no longer used to route metrics and can be omitted.
</Note>

## Troubleshooting Metrics

### Metrics Sent to `unknown_metrics`

`unknown_metrics` was the default destination in the legacy metrics experience when no dataset was specified with the `x-honeycomb-dataset` header.
With the current metrics experience, metrics are routed to the managed `Metrics` dataset automatically, so this no longer applies.

<Info>
  This troubleshooting scenario is not applicable to [Honeycomb Classic users](/troubleshoot/product-lifecycle/recommended-migrations/#migrate-from-honeycomb-classic-to-honeycomb-environments).
</Info>