otel: go.opentelemetry.io/otel/plugin/othttp Index | Examples | Files

package othttp

import "go.opentelemetry.io/otel/plugin/othttp"

Package othttp provides a http.Handler and functions that are intended to be used to add tracing by wrapping existing handlers (with Handler) and routes WithRouteTag.



Package Files

doc.go handler.go wrap.go


const (
    HostKey       = core.Key("http.host")        // the http host (http.Request.Host)
    MethodKey     = core.Key("http.method")      // the http method (http.Request.Method)
    PathKey       = core.Key("http.path")        // the http path (http.Request.URL.Path)
    URLKey        = core.Key("http.url")         // the http url (http.Request.URL.String())
    UserAgentKey  = core.Key("http.user_agent")  // the http user agent (http.Request.UserAgent())
    RouteKey      = core.Key("http.route")       // the http route (ex: /users/:id)
    StatusCodeKey = core.Key("http.status_code") // if set, the http status
    ReadBytesKey  = core.Key("http.read_bytes")  // if anything was read from the request body, the total number of bytes read
    ReadErrorKey  = core.Key("http.read_error")  // If an error occurred while reading a request, the string of the error (io.EOF is not recorded)
    WroteBytesKey = core.Key("http.wrote_bytes") // if anything was written to the response writer, the total number of bytes written
    WriteErrorKey = core.Key("http.write_error") // if an error occurred while writing a reply, the string of the error (io.EOF is not recorded)

Attribute keys that the Handler can add to a span.

const (
    ReadEvents event = iota

Different types of events that can be recorded, see WithMessageEvents

func NewHandler Uses

func NewHandler(handler http.Handler, operation string, opts ...Option) http.Handler

NewHandler wraps the passed handler, functioning like middleware, in a span named after the operation and with any provided HandlerOptions.


/* curl -v -d "a painting" http://localhost:7777/hello/bob/ross
* upload completely sent off: 10 out of 10 bytes
< HTTP/1.1 200 OK
< Traceparent: 00-76ae040ee5753f38edf1c2bd9bd128bd-dd394138cfd7a3dc-01
< Date: Fri, 04 Oct 2019 02:33:08 GMT
< Content-Length: 45
< Content-Type: text/plain; charset=utf-8
Hello, bob/ross!
You sent me this:
a painting

// Write spans to stdout
exporter, err := stdout.NewExporter(stdout.Options{PrettyPrint: true})
if err != nil {

tp, err := sdktrace.NewProvider(sdktrace.WithConfig(sdktrace.Config{DefaultSampler: sdktrace.AlwaysSample()}),
if err != nil {

figureOutName := func(ctx context.Context, s string) (string, error) {
    pp := strings.SplitN(s, "/", 2)
    var err error
    switch pp[1] {
    case "":
        err = fmt.Errorf("expected /hello/:name in %q", s)
    return pp[1], err

var mux http.ServeMux
    othttp.WithRouteTag("/hello/:name", http.HandlerFunc(
        func(w http.ResponseWriter, r *http.Request) {
            ctx := r.Context()
            var name string
            // Wrap another function in its own span
            if err := trace.SpanFromContext(ctx).Tracer().WithSpan(ctx, "figureOutName",
                func(ctx context.Context) error {
                    var err error
                    name, err = figureOutName(ctx, r.URL.Path[1:])
                    return err
                }); err != nil {
                log.Println("error figuring out name: ", err)
                http.Error(w, err.Error(), http.StatusInternalServerError)

            d, err := ioutil.ReadAll(r.Body)
            if err != nil {
                log.Println("error reading body: ", err)

            n, err := io.WriteString(w, "Hello, "+name+"!\nYou sent me this:\n"+string(d))
            if err != nil {
                log.Printf("error writing reply after %d bytes: %s", n, err)

if err := http.ListenAndServe(":7777",
    othttp.NewHandler(&mux, "server",
        othttp.WithMessageEvents(othttp.ReadEvents, othttp.WriteEvents),
); err != nil {

func WithRouteTag Uses

func WithRouteTag(route string, h http.Handler) http.Handler

WithRouteTag annotates a span with the provided route name using the RouteKey Tag.

type Handler Uses

type Handler struct {
    // contains filtered or unexported fields

Handler is http middleware that corresponds to the http.Handler interface and is designed to wrap a http.Mux (or equivalent), while individual routes on the mux are wrapped with WithRouteTag. A Handler will add various attributes to the span using the core.Keys defined in this package.

func (*Handler) ServeHTTP Uses

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request)

ServeHTTP serves HTTP requests (http.Handler)

type Option Uses

type Option func(*Handler)

Option function used for setting *optional* Handler properties

func WithMessageEvents Uses

func WithMessageEvents(events ...event) Option

WithMessageEvents configures the Handler to record the specified events (span.AddEvent) on spans. By default only summary attributes are added at the end of the request.

Valid events are:

* ReadEvents: Record the number of bytes read after every http.Request.Body.Read
  using the ReadBytesKey
* WriteEvents: Record the number of bytes written after every http.ResponeWriter.Write
  using the WriteBytesKey

func WithPropagators Uses

func WithPropagators(ps propagation.Propagators) Option

WithPropagators configures the Handler with specific propagators. If this option isn't specified then Propagators with go.opentelemetry.io/otel/api/trace.DefaultHTTPPropagator are used.

func WithPublicEndpoint Uses

func WithPublicEndpoint() Option

WithPublicEndpoint configures the Handler to link the span with an incoming span context. If this option is not provided, then the association is a child association instead of a link.

func WithSpanOptions Uses

func WithSpanOptions(opts ...trace.StartOption) Option

WithSpanOptions configures the Handler with an additional set of trace.StartOptions, which are applied to each new span.

func WithTracer Uses

func WithTracer(tracer trace.Tracer) Option

WithTracer configures the Handler with a specific tracer. If this option isn't specified then the global tracer is used.

Package othttp imports 8 packages (graph). Updated 2020-02-21. Refresh now. Tools for package owners.