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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package otelmux // import "go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux"
import (
"fmt"
"net/http"
"sync"
"github.com/felixge/httpsnoop"
"github.com/gorilla/mux"
"go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux/internal/semconvutil"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/propagation"
semconv "go.opentelemetry.io/otel/semconv/v1.20.0"
"go.opentelemetry.io/otel/trace"
)
const (
// ScopeName is the instrumentation scope name.
ScopeName = "go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux"
)
// Middleware sets up a handler to start tracing the incoming
// requests. The service parameter should describe the name of the
// (virtual) server handling the request.
func Middleware(service string, opts ...Option) mux.MiddlewareFunc {
cfg := config{}
for _, opt := range opts {
opt.apply(&cfg)
}
if cfg.TracerProvider == nil {
cfg.TracerProvider = otel.GetTracerProvider()
}
tracer := cfg.TracerProvider.Tracer(
ScopeName,
trace.WithInstrumentationVersion(Version()),
)
if cfg.Propagators == nil {
cfg.Propagators = otel.GetTextMapPropagator()
}
if cfg.spanNameFormatter == nil {
cfg.spanNameFormatter = defaultSpanNameFunc
}
return func(handler http.Handler) http.Handler {
return traceware{
service: service,
tracer: tracer,
propagators: cfg.Propagators,
handler: handler,
spanNameFormatter: cfg.spanNameFormatter,
publicEndpoint: cfg.PublicEndpoint,
publicEndpointFn: cfg.PublicEndpointFn,
filters: cfg.Filters,
}
}
}
type traceware struct {
service string
tracer trace.Tracer
propagators propagation.TextMapPropagator
handler http.Handler
spanNameFormatter func(string, *http.Request) string
publicEndpoint bool
publicEndpointFn func(*http.Request) bool
filters []Filter
}
type recordingResponseWriter struct {
writer http.ResponseWriter
written bool
status int
}
var rrwPool = &sync.Pool{
New: func() interface{} {
return &recordingResponseWriter{}
},
}
func getRRW(writer http.ResponseWriter) *recordingResponseWriter {
rrw := rrwPool.Get().(*recordingResponseWriter)
rrw.written = false
rrw.status = http.StatusOK
rrw.writer = httpsnoop.Wrap(writer, httpsnoop.Hooks{
Write: func(next httpsnoop.WriteFunc) httpsnoop.WriteFunc {
return func(b []byte) (int, error) {
if !rrw.written {
rrw.written = true
}
return next(b)
}
},
WriteHeader: func(next httpsnoop.WriteHeaderFunc) httpsnoop.WriteHeaderFunc {
return func(statusCode int) {
if !rrw.written {
rrw.written = true
rrw.status = statusCode
}
next(statusCode)
}
},
})
return rrw
}
func putRRW(rrw *recordingResponseWriter) {
rrw.writer = nil
rrwPool.Put(rrw)
}
// defaultSpanNameFunc just reuses the route name as the span name.
func defaultSpanNameFunc(routeName string, _ *http.Request) string { return routeName }
// ServeHTTP implements the http.Handler interface. It does the actual
// tracing of the request.
func (tw traceware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
for _, f := range tw.filters {
if !f(r) {
// Simply pass through to the handler if a filter rejects the request
tw.handler.ServeHTTP(w, r)
return
}
}
ctx := tw.propagators.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
routeStr := ""
route := mux.CurrentRoute(r)
if route != nil {
var err error
routeStr, err = route.GetPathTemplate()
if err != nil {
routeStr, err = route.GetPathRegexp()
if err != nil {
routeStr = ""
}
}
}
opts := []trace.SpanStartOption{
trace.WithAttributes(semconvutil.HTTPServerRequest(tw.service, r)...),
trace.WithSpanKind(trace.SpanKindServer),
}
if tw.publicEndpoint || (tw.publicEndpointFn != nil && tw.publicEndpointFn(r.WithContext(ctx))) {
opts = append(opts, trace.WithNewRoot())
// Linking incoming span context if any for public endpoint.
if s := trace.SpanContextFromContext(ctx); s.IsValid() && s.IsRemote() {
opts = append(opts, trace.WithLinks(trace.Link{SpanContext: s}))
}
}
if routeStr == "" {
routeStr = fmt.Sprintf("HTTP %s route not found", r.Method)
} else {
rAttr := semconv.HTTPRoute(routeStr)
opts = append(opts, trace.WithAttributes(rAttr))
}
spanName := tw.spanNameFormatter(routeStr, r)
ctx, span := tw.tracer.Start(ctx, spanName, opts...)
defer span.End()
r2 := r.WithContext(ctx)
rrw := getRRW(w)
defer putRRW(rrw)
tw.handler.ServeHTTP(rrw.writer, r2)
if rrw.status > 0 {
span.SetAttributes(semconv.HTTPStatusCode(rrw.status))
}
span.SetStatus(semconvutil.HTTPServerStatus(rrw.status))
}
|
