# OpenTelemetry-Go

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The Go [OpenTelemetry](https://opentelemetry.io/) client.

## Installation

This repository includes multiple packages. The `api`
package contains core data types, interfaces and no-op implementations that comprise the OpenTelemetry API following
[the
specification](https://github.com/open-telemetry/opentelemetry-specification).
The `sdk` package is the reference implementation of the API.

Libraries that produce telemetry data should only depend on `api`,
and defer the choice of the SDK to the application developer. Applications may
depend on `sdk` or another package that implements the API. 

To install the API and SDK packages,

```
$ go get -u go.opentelemetry.io
```

## Quick Start

```go
package main

import (
	"context"
	"log"

	apitrace "go.opentelemetry.io/api/trace"
	"go.opentelemetry.io/exporter/trace/stdout"
	sdktrace "go.opentelemetry.io/sdk/trace"
)

func initTracer() {
	sdktrace.Register()

	exporter, err := stdout.NewExporter(stdout.Options{PrettyPrint: true})
	if err != nil {
		log.Fatal(err)
	}

	ssp := sdktrace.NewSimpleSpanProcessor(exporter)
	sdktrace.RegisterSpanProcessor(ssp)

	// For the demonstration, use sdktrace.AlwaysSample sampler to sample all traces.
	// In a production application, use sdktrace.ProbabilitySampler with a desired probability.
	sdktrace.ApplyConfig(sdktrace.Config{DefaultSampler: sdktrace.AlwaysSample()})
}

func main() {
	initTracer()

	apitrace.GlobalTracer().WithSpan(context.Background(), "foo",
		func(ctx context.Context) error {
			apitrace.GlobalTracer().WithSpan(ctx, "bar",
				func(ctx context.Context) error {
					apitrace.GlobalTracer().WithSpan(ctx, "baz",
						func(ctx context.Context) error {
							return nil
						},
					)
					return nil
				},
			)
			return nil
		},
	)
}

```

See the [API
documentation](https://go.opentelemetry.io/) for more
detail, and the
[opentelemetry-example-app](./example/README.md)
for a complete example.

## Contributing

See the [contributing file](CONTRIBUTING.md).

## Release Schedule

OpenTelemetry Go is under active development. Below is the release schedule
for the Go library. The first version of release isn't guaranteed to conform
to a specific version of the specification, and future releases will not
attempt to maintain backwards compatibility with the alpha release.

| Component                   | Version | Target Date     |
| --------------------------- | ------- | --------------- |
| Tracing API                 | Alpha   | October 28 2019 |
| Tracing SDK                 | Alpha   | October 28 2019 |
| Metrics API                 | Alpha   | October 28 2019 |
| Metrics SDK                 | Alpha   | October 28 2019 |
| Zipkin Trace Exporter       | Alpha   | Unknown         |
| Jaeger Trace Exporter       | Alpha   | October 28 2019 |
| Prometheus Metrics Exporter | Alpha   | October 28 2019 |
| Trace Context Propagation   | Alpha   | Unknown         |
| OpenTracing Bridge          | Alpha   | October         |
| OpenCensus Bridge           | Alpha   | Unknown         |