forked from riandyrn/otelchi
/
middleware.go
258 lines (225 loc) · 7.08 KB
/
middleware.go
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package otelchi
import (
"encoding/json"
"fmt"
"io"
"net/http"
"os"
"sync"
"github.com/felixge/httpsnoop"
"github.com/go-chi/chi/v5"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/propagation"
datautils "github.com/helios/go-sdk/data-utils"
otelcontrib "go.opentelemetry.io/contrib"
semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
oteltrace "go.opentelemetry.io/otel/trace"
)
const (
tracerName = "github.com/helios/otelchi"
)
type bodyWrapper struct {
io.ReadCloser
read int64
err error
requestBody []byte
metadataOnly bool
contentType string
}
func (w *bodyWrapper) Read(b []byte) (int, error) {
n, err := w.ReadCloser.Read(b)
if n > 0 && !w.metadataOnly{
shouldSkipContentByType, _ := datautils.ShouldSkipContentCollectionByContentType(w.contentType)
if !shouldSkipContentByType {
w.requestBody = append(w.requestBody, b[0:n]...)
}
}
n1 := int64(n)
w.read += n1
w.err = err
return n, err
}
func (w *bodyWrapper) Close() error {
return w.ReadCloser.Close()
}
// Middleware sets up a handler to start tracing the incoming
// requests. The serverName parameter should describe the name of the
// (virtual) server handling the request.
func Middleware(serverName string, opts ...Option) func(next http.Handler) http.Handler {
cfg := config{}
for _, opt := range opts {
opt.apply(&cfg)
}
if cfg.TracerProvider == nil {
cfg.TracerProvider = otel.GetTracerProvider()
}
tracer := cfg.TracerProvider.Tracer(
tracerName,
oteltrace.WithInstrumentationVersion(otelcontrib.SemVersion()),
)
if cfg.Propagators == nil {
cfg.Propagators = otel.GetTextMapPropagator()
}
return func(handler http.Handler) http.Handler {
return traceware{
serverName: serverName,
tracer: tracer,
propagators: cfg.Propagators,
handler: handler,
chiRoutes: cfg.ChiRoutes,
reqMethodInSpanName: cfg.RequestMethodInSpanName,
metadataOnly: os.Getenv("HS_METADATA_ONLY") == "true",
filter: cfg.Filter,
}
}
}
type traceware struct {
serverName string
tracer oteltrace.Tracer
propagators propagation.TextMapPropagator
handler http.Handler
chiRoutes chi.Routes
reqMethodInSpanName bool
metadataOnly bool
filter func(r *http.Request) bool
}
type recordingResponseWriter struct {
writer http.ResponseWriter
written bool
status int
responseBody []byte
metadataOnly bool
}
var rrwPool = &sync.Pool{
New: func() interface{} {
return &recordingResponseWriter{}
},
}
func getRRW(writer http.ResponseWriter) *recordingResponseWriter {
rrw := rrwPool.Get().(*recordingResponseWriter)
rrw.written = false
rrw.status = 0
rrw.responseBody = []byte{}
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
rrw.status = http.StatusOK
}
if !rrw.metadataOnly && len(b) > 0 {
respContentType := writer.Header().Get("Content-Type")
shouldSkipContentByType, _ := datautils.ShouldSkipContentCollectionByContentType(respContentType)
if !shouldSkipContentByType {
rrw.responseBody = append(rrw.responseBody, b...)
}
}
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)
}
func collectRequestHeaders(r *http.Request, span oteltrace.Span) {
headersStr, err := json.Marshal(r.Header)
if err == nil {
span.SetAttributes(attribute.KeyValue{Key: "http.request.headers", Value: attribute.StringValue(string(headersStr))})
}
}
// ServeHTTP implements the http.Handler interface. It does the actual
// tracing of the request.
func (tw traceware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// skip if filter returns false
if tw.filter != nil && !tw.filter(r) {
tw.handler.ServeHTTP(w, r)
return
}
metadataOnly := tw.metadataOnly
// extract tracing header using propagator
ctx := tw.propagators.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
// create span, based on specification, we need to set already known attributes
// when creating the span, the only thing missing here is HTTP route pattern since
// in go-chi/chi route pattern could only be extracted once the request is executed
// check here for details:
//
// https://github.com/go-chi/chi/issues/150#issuecomment-278850733
//
// if we have access to chi routes, we could extract the route pattern beforehand.
spanName := ""
routePattern := ""
if tw.chiRoutes != nil {
rctx := chi.NewRouteContext()
if tw.chiRoutes.Match(rctx, r.Method, r.URL.Path) {
routePattern = rctx.RoutePattern()
spanName = addPrefixToSpanName(tw.reqMethodInSpanName, r.Method, routePattern)
}
}
var bw bodyWrapper
bw.metadataOnly = metadataOnly
if r.Body != nil && r.Body != http.NoBody {
bw.contentType = r.Header.Get("Content-type")
bw.ReadCloser = r.Body
r.Body = &bw
}
ctx, span := tw.tracer.Start(
ctx, spanName,
oteltrace.WithAttributes(semconv.NetAttributesFromHTTPRequest("tcp", r)...),
oteltrace.WithAttributes(semconv.EndUserAttributesFromHTTPRequest(r)...),
oteltrace.WithAttributes(semconv.HTTPServerAttributesFromHTTPRequest(tw.serverName, routePattern, r)...),
oteltrace.WithSpanKind(oteltrace.SpanKindServer),
)
defer span.End()
// get recording response writer
rrw := getRRW(w)
rrw.metadataOnly = metadataOnly
defer putRRW(rrw)
// execute next http handler
r = r.WithContext(ctx)
tw.handler.ServeHTTP(rrw.writer, r)
// set span name & http route attribute if necessary
if len(routePattern) == 0 {
routePattern = chi.RouteContext(r.Context()).RoutePattern()
span.SetAttributes(semconv.HTTPRouteKey.String(routePattern))
spanName = addPrefixToSpanName(tw.reqMethodInSpanName, r.Method, routePattern)
span.SetName(spanName)
}
// Add traceresponse header
if span.IsRecording() {
spanCtx := span.SpanContext()
rrw.writer.Header().Add("traceresponse", fmt.Sprintf("00-%s-%s-01", spanCtx.TraceID().String(), spanCtx.SpanID().String()))
}
// set status code attribute
span.SetAttributes(semconv.HTTPStatusCodeKey.Int(rrw.status))
// set span status
spanStatus, spanMessage := semconv.SpanStatusFromHTTPStatusCode(rrw.status)
span.SetStatus(spanStatus, spanMessage)
if !metadataOnly {
collectRequestHeaders(r, span)
if len(bw.requestBody) > 0 {
span.SetAttributes(attribute.KeyValue{Key: "http.request.body", Value: attribute.StringValue(string(bw.requestBody))})
}
if len(rrw.responseBody) > 0 {
span.SetAttributes(attribute.KeyValue{Key: "http.response.body", Value: attribute.StringValue(string(rrw.responseBody))})
}
}
}
func addPrefixToSpanName(shouldAdd bool, prefix, spanName string) string {
if shouldAdd && len(spanName) > 0 {
spanName = prefix + " " + spanName
}
return spanName
}