opentracing

package main

import (
	// ddtrace namespace is suggested
	ddtrace "github.com/DataDog/dd-trace-go/opentracing"
	opentracing "github.com/opentracing/opentracing-go"
)

func main() {
	// create a Tracer configuration
	config := ddtrace.NewConfiguration()
	config.ServiceName = "api-intake"
	config.AgentHostname = "ddagent.consul.local"

	// initialize a Tracer and ensure a graceful shutdown
	// using the `closer.Close()`
	tracer, closer, err := ddtrace.NewTracer(config)
	if err != nil {
		// handle the configuration error
	}
	defer closer.Close()

	// set the Datadog tracer as a GlobalTracer
	opentracing.SetGlobalTracer(tracer)
	startWebServer()
}

func startWebServer() {
	// start a web server
}

Output:

You can leverage the Golang `Context` for intra-process propagation of Spans. In this example we create a root Span, so that it can be reused in a nested function to create a child Span.

package main

import (
	"context"

	opentracing "github.com/opentracing/opentracing-go"
)

// You can leverage the Golang `Context` for intra-process propagation of
// Spans. In this example we create a root Span, so that it can be reused
// in a nested function to create a child Span.
func main() {
	// create a new root Span and return a new Context that includes
	// the Span itself
	ctx := context.Background()
	rootSpan, ctx := opentracing.StartSpanFromContext(ctx, "web.request")
	defer rootSpan.Finish()

	requestHandler(ctx)
}

func requestHandler(ctx context.Context) {
	// retrieve the previously set root Span
	span := opentracing.SpanFromContext(ctx)
	span.SetTag("resource.name", "/")

	// or simply create a new child Span from the previous Context
	childSpan, _ := opentracing.StartSpanFromContext(ctx, "sql.query")
	defer childSpan.Finish()
}

Output:

You can use the GlobalTracer to create a root Span. If you need to create a hierarchy, simply use the `ChildOf` reference

package main

import (
	opentracing "github.com/opentracing/opentracing-go"
)

// You can use the GlobalTracer to create a root Span. If you need to create a hierarchy,
// simply use the `ChildOf` reference
func main() {
	// use the GlobalTracer previously set
	rootSpan := opentracing.StartSpan("web.request")
	defer rootSpan.Finish()

	// set the reference to create a hierarchy of spans
	reference := opentracing.ChildOf(rootSpan.Context())
	childSpan := opentracing.StartSpan("sql.query", reference)
	defer childSpan.Finish()

	dbQuery()
}

func dbQuery() {
	// start a database query
}

Output: