peridot/vendor/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp/handler.go

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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package otelhttp // import "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
import (
"net/http"
"time"
"github.com/felixge/httpsnoop"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp/internal/semconv"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp/internal/semconvutil"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/metric"
"go.opentelemetry.io/otel/propagation"
"go.opentelemetry.io/otel/trace"
)
// middleware is an http middleware which wraps the next handler in a span.
type middleware struct {
operation string
server string
tracer trace.Tracer
meter metric.Meter
propagators propagation.TextMapPropagator
spanStartOptions []trace.SpanStartOption
readEvent bool
writeEvent bool
filters []Filter
spanNameFormatter func(string, *http.Request) string
publicEndpoint bool
publicEndpointFn func(*http.Request) bool
traceSemconv semconv.HTTPServer
requestBytesCounter metric.Int64Counter
responseBytesCounter metric.Int64Counter
serverLatencyMeasure metric.Float64Histogram
}
func defaultHandlerFormatter(operation string, _ *http.Request) string {
return operation
}
// NewHandler wraps the passed handler in a span named after the operation and
// enriches it with metrics.
func NewHandler(handler http.Handler, operation string, opts ...Option) http.Handler {
return NewMiddleware(operation, opts...)(handler)
}
// NewMiddleware returns a tracing and metrics instrumentation middleware.
// The handler returned by the middleware wraps a handler
// in a span named after the operation and enriches it with metrics.
func NewMiddleware(operation string, opts ...Option) func(http.Handler) http.Handler {
h := middleware{
operation: operation,
traceSemconv: semconv.NewHTTPServer(),
}
defaultOpts := []Option{
WithSpanOptions(trace.WithSpanKind(trace.SpanKindServer)),
WithSpanNameFormatter(defaultHandlerFormatter),
}
c := newConfig(append(defaultOpts, opts...)...)
h.configure(c)
h.createMeasures()
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
h.serveHTTP(w, r, next)
})
}
}
func (h *middleware) configure(c *config) {
h.tracer = c.Tracer
h.meter = c.Meter
h.propagators = c.Propagators
h.spanStartOptions = c.SpanStartOptions
h.readEvent = c.ReadEvent
h.writeEvent = c.WriteEvent
h.filters = c.Filters
h.spanNameFormatter = c.SpanNameFormatter
h.publicEndpoint = c.PublicEndpoint
h.publicEndpointFn = c.PublicEndpointFn
h.server = c.ServerName
}
func handleErr(err error) {
if err != nil {
otel.Handle(err)
}
}
func (h *middleware) createMeasures() {
var err error
h.requestBytesCounter, err = h.meter.Int64Counter(
serverRequestSize,
metric.WithUnit("By"),
metric.WithDescription("Measures the size of HTTP request messages."),
)
handleErr(err)
h.responseBytesCounter, err = h.meter.Int64Counter(
serverResponseSize,
metric.WithUnit("By"),
metric.WithDescription("Measures the size of HTTP response messages."),
)
handleErr(err)
h.serverLatencyMeasure, err = h.meter.Float64Histogram(
serverDuration,
metric.WithUnit("ms"),
metric.WithDescription("Measures the duration of inbound HTTP requests."),
)
handleErr(err)
}
// serveHTTP sets up tracing and calls the given next http.Handler with the span
// context injected into the request context.
func (h *middleware) serveHTTP(w http.ResponseWriter, r *http.Request, next http.Handler) {
requestStartTime := time.Now()
for _, f := range h.filters {
if !f(r) {
// Simply pass through to the handler if a filter rejects the request
next.ServeHTTP(w, r)
return
}
}
ctx := h.propagators.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
opts := []trace.SpanStartOption{
trace.WithAttributes(h.traceSemconv.RequestTraceAttrs(h.server, r)...),
}
opts = append(opts, h.spanStartOptions...)
if h.publicEndpoint || (h.publicEndpointFn != nil && h.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}))
}
}
tracer := h.tracer
if tracer == nil {
if span := trace.SpanFromContext(r.Context()); span.SpanContext().IsValid() {
tracer = newTracer(span.TracerProvider())
} else {
tracer = newTracer(otel.GetTracerProvider())
}
}
ctx, span := tracer.Start(ctx, h.spanNameFormatter(h.operation, r), opts...)
defer span.End()
readRecordFunc := func(int64) {}
if h.readEvent {
readRecordFunc = func(n int64) {
span.AddEvent("read", trace.WithAttributes(ReadBytesKey.Int64(n)))
}
}
var bw bodyWrapper
// if request body is nil or NoBody, we don't want to mutate the body as it
// will affect the identity of it in an unforeseeable way because we assert
// ReadCloser fulfills a certain interface and it is indeed nil or NoBody.
if r.Body != nil && r.Body != http.NoBody {
bw.ReadCloser = r.Body
bw.record = readRecordFunc
r.Body = &bw
}
writeRecordFunc := func(int64) {}
if h.writeEvent {
writeRecordFunc = func(n int64) {
span.AddEvent("write", trace.WithAttributes(WroteBytesKey.Int64(n)))
}
}
rww := &respWriterWrapper{
ResponseWriter: w,
record: writeRecordFunc,
ctx: ctx,
props: h.propagators,
statusCode: http.StatusOK, // default status code in case the Handler doesn't write anything
}
// Wrap w to use our ResponseWriter methods while also exposing
// other interfaces that w may implement (http.CloseNotifier,
// http.Flusher, http.Hijacker, http.Pusher, io.ReaderFrom).
w = httpsnoop.Wrap(w, httpsnoop.Hooks{
Header: func(httpsnoop.HeaderFunc) httpsnoop.HeaderFunc {
return rww.Header
},
Write: func(httpsnoop.WriteFunc) httpsnoop.WriteFunc {
return rww.Write
},
WriteHeader: func(httpsnoop.WriteHeaderFunc) httpsnoop.WriteHeaderFunc {
return rww.WriteHeader
},
Flush: func(httpsnoop.FlushFunc) httpsnoop.FlushFunc {
return rww.Flush
},
})
labeler, found := LabelerFromContext(ctx)
if !found {
ctx = ContextWithLabeler(ctx, labeler)
}
next.ServeHTTP(w, r.WithContext(ctx))
span.SetStatus(semconv.ServerStatus(rww.statusCode))
span.SetAttributes(h.traceSemconv.ResponseTraceAttrs(semconv.ResponseTelemetry{
StatusCode: rww.statusCode,
ReadBytes: bw.read.Load(),
ReadError: bw.err,
WriteBytes: rww.written,
WriteError: rww.err,
})...)
// Add metrics
attributes := append(labeler.Get(), semconvutil.HTTPServerRequestMetrics(h.server, r)...)
if rww.statusCode > 0 {
attributes = append(attributes, semconv.HTTPStatusCode(rww.statusCode))
}
o := metric.WithAttributeSet(attribute.NewSet(attributes...))
addOpts := []metric.AddOption{o} // Allocate vararg slice once.
h.requestBytesCounter.Add(ctx, bw.read.Load(), addOpts...)
h.responseBytesCounter.Add(ctx, rww.written, addOpts...)
// Use floating point division here for higher precision (instead of Millisecond method).
elapsedTime := float64(time.Since(requestStartTime)) / float64(time.Millisecond)
h.serverLatencyMeasure.Record(ctx, elapsedTime, o)
}
// WithRouteTag annotates spans and metrics with the provided route name
// with HTTP route attribute.
func WithRouteTag(route string, h http.Handler) http.Handler {
attr := semconv.NewHTTPServer().Route(route)
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
span := trace.SpanFromContext(r.Context())
span.SetAttributes(attr)
labeler, _ := LabelerFromContext(r.Context())
labeler.Add(attr)
h.ServeHTTP(w, r)
})
}