httptrace.go

// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2016 Datadog, Inc.

// Package httptrace provides functionalities to trace HTTP requests that are commonly required and used across
// contrib/** integrations.
package httptrace

import (
	"context"
	"fmt"
	"net/http"
	"strconv"

	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
)

// StartRequestSpan starts an HTTP request span with the standard list of HTTP request span tags. URL query parameters
// are added to the URL tag when queryParams is true. Any further span start option can be added with opts.
func StartRequestSpan(r *http.Request, service, resource string, queryParams bool, opts ...ddtrace.StartSpanOption) (tracer.Span, context.Context) {
	path := r.URL.Path
	if queryParams {
		path += "?" + r.URL.RawQuery
	}
	opts = append([]ddtrace.StartSpanOption{
		tracer.SpanType(ext.SpanTypeWeb),
		tracer.ServiceName(service),
		tracer.ResourceName(resource),
		tracer.Tag(ext.HTTPMethod, r.Method),
		tracer.Tag(ext.HTTPURL, path),
		tracer.Tag(ext.HTTPUserAgent, r.UserAgent()),
	}, opts...)
	if r.URL.Host != "" {
		opts = append([]ddtrace.StartSpanOption{
			tracer.Tag("http.host", r.URL.Host),
		}, opts...)
	}
	if spanctx, err := tracer.Extract(tracer.HTTPHeadersCarrier(r.Header)); err == nil {
		opts = append(opts, tracer.ChildOf(spanctx))
	}
	return tracer.StartSpanFromContext(r.Context(), "http.request", opts...)
}

// FinishRequestSpan finishes the given HTTP request span with the standard list of HTTP request span tags.
// Any further span finish option can be added with opts.
func FinishRequestSpan(s tracer.Span, status int, opts ...tracer.FinishOption) {
	var statusStr string
	if status == 0 {
		statusStr = "200"
	} else {
		statusStr = strconv.Itoa(status)
	}
	s.SetTag(ext.HTTPCode, statusStr)
	if status >= 500 && status < 600 {
		s.SetTag(ext.Error, fmt.Errorf("%d: %s", status, http.StatusText(status)))
	}
	s.Finish(opts...)
}