---
title: tracing (Caddyfile directive)
---

# tracing

It provides integration with OpenTelemetry tracing facilities.

When enabled, it will propagate an existing trace context or initialize a new one.

It is based on [github.com/open-telemetry/opentelemetry-go](https://github.com/open-telemetry/opentelemetry-go).

It uses [gRPC](https://github.com/grpc/) as an exporter protocol and  W3C [tracecontext](https://www.w3.org/TR/trace-context/) and [baggage](https://www.w3.org/TR/baggage/) as propagators.

## Syntax

```caddy-d
tracing {
	[span <span_name>]
}
```

- **&lt;span_name&gt;** is a span name. Please see span [naming guidelines](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.7.0/specification/trace/api.md).

  [Placeholders](/docs/caddyfile/concepts#placeholders) may be used in span names; keep in mind that tracing happens as early as possible, so only request placeholders may be used, and not response placeholders.

## Configuration

### Environment variables

It can be configured using the environment variables defined
by the [OpenTelemetry Environment Variable Specification](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/sdk-environment-variables.md).

For the exporter configuration details, please
see [spec](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.7.0/specification/protocol/exporter.md).

For example:

```bash
export OTEL_EXPORTER_OTLP_HEADERS="myAuthHeader=myToken,anotherHeader=value"
export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=https://my-otlp-endpoint:55680
```

## Examples

Here is a **Caddyfile** example:

```caddy-d
handle /example* {
	tracing {
		span example
	}
	reverse_proxy 127.0.0.1:8081
}
```