![Tracing — Structured, application-level diagnostics][splash]
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# Tracing OpenTelemetry
Utilities for adding [OpenTelemetry] interoperability to [`tracing`].
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[crates-url]: https://crates.io/crates/tracing-opentelemetry/0.22.0
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[docs-url]: https://docs.rs/tracing-opentelemetry/0.22.0/tracing_opentelemetry
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## Overview
[`tracing`] is a framework for instrumenting Rust programs to collect
structured, event-based diagnostic information. This crate provides a
subscriber that connects spans from multiple systems into a trace and
emits them to [OpenTelemetry]-compatible distributed tracing systems
for processing and visualization.
The crate provides the following types:
* [`OpenTelemetryLayer`] adds OpenTelemetry context to all `tracing` [span]s.
* [`OpenTelemetrySpanExt`] allows OpenTelemetry parent trace information to be
injected and extracted from a `tracing` [span].
[`OpenTelemetryLayer`]: https://docs.rs/tracing-opentelemetry/latest/tracing_opentelemetry/struct.OpenTelemetryLayer.html
[`OpenTelemetrySpanExt`]: https://docs.rs/tracing-opentelemetry/latest/tracing_opentelemetry/trait.OpenTelemetrySpanExt.html
[span]: https://docs.rs/tracing/latest/tracing/span/index.html
[`tracing`]: https://crates.io/crates/tracing
[OpenTelemetry]: https://opentelemetry.io/
## Compatibility with OpenTelemetry crates
Note that version numbers for this crate are **not** synchronized with the
various OpenTelemetry crates, despite having similar version numbers. For
discussion, see [issue #170](https://github.com/tokio-rs/tracing-opentelemetry/issues/170).
As of 0.26, tracing-opentelemetry is one version ahead of the opentelemetry
crates, such that tracing-opentelemetry 0.26.0 is compatible with opentelemetry 0.25.0,
but due to semver compatibility concerns, this may not always be the case.
## Visualizing traces with Jaeger
```console
# Run a supported collector like jaeger in the background
$ docker run -d -p4317:4317 -p16686:16686 jaegertracing/all-in-one:latest
# Run example to produce spans (from parent examples directory)
$ cargo run --example opentelemetry-otlp
# View spans (see the image below)
$ firefox http://localhost:16686/
```
## Feature Flags
- `metrics`: Enables the [`MetricsLayer`] type, a [layer] that
exports OpenTelemetry metrics from specifically-named events. This enables
the `metrics` feature flag on the `opentelemetry` crate.
[`MetricsLayer`]: https://docs.rs/tracing-opentelemetry/latest/tracing_opentelemetry/struct.MetricsLayer.html
[layer]: https://docs.rs/tracing-subscriber/latest/tracing_subscriber/layer/trait.Layer.html
## License
This project is licensed under the [MIT license](LICENSE).
### Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in Tracing by you, shall be licensed as MIT, without any additional
terms or conditions.
