97 lines
2.6 KiB
Go
97 lines
2.6 KiB
Go
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// +build go1.7
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package nethttp
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import (
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"net/http"
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opentracing "github.com/opentracing/opentracing-go"
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"github.com/opentracing/opentracing-go/ext"
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)
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type statusCodeTracker struct {
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http.ResponseWriter
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status int
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}
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func (w *statusCodeTracker) WriteHeader(status int) {
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w.status = status
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w.ResponseWriter.WriteHeader(status)
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}
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type mwOptions struct {
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opNameFunc func(r *http.Request) string
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componentName string
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}
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// MWOption controls the behavior of the Middleware.
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type MWOption func(*mwOptions)
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// OperationNameFunc returns a MWOption that uses given function f
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// to generate operation name for each server-side span.
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func OperationNameFunc(f func(r *http.Request) string) MWOption {
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return func(options *mwOptions) {
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options.opNameFunc = f
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}
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}
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// MWComponentName returns a MWOption that sets the component name
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// name for the server-side span.
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func MWComponentName(componentName string) MWOption {
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return func(options *mwOptions) {
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options.componentName = componentName
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}
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}
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// Middleware wraps an http.Handler and traces incoming requests.
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// Additionally, it adds the span to the request's context.
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//
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// By default, the operation name of the spans is set to "HTTP {method}".
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// This can be overriden with options.
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//
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// Example:
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// http.ListenAndServe("localhost:80", nethttp.Middleware(tracer, http.DefaultServeMux))
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//
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// The options allow fine tuning the behavior of the middleware.
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//
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// Example:
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// mw := nethttp.Middleware(
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// tracer,
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// http.DefaultServeMux,
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// nethttp.OperationName(func(r *http.Request) string {
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// return "HTTP " + r.Method + ":/api/customers"
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// }),
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// )
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func Middleware(tr opentracing.Tracer, h http.Handler, options ...MWOption) http.Handler {
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opts := mwOptions{
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opNameFunc: func(r *http.Request) string {
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return "HTTP " + r.Method
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},
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}
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for _, opt := range options {
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opt(&opts)
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}
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fn := func(w http.ResponseWriter, r *http.Request) {
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ctx, _ := tr.Extract(opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(r.Header))
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sp := tr.StartSpan(opts.opNameFunc(r), ext.RPCServerOption(ctx))
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ext.HTTPMethod.Set(sp, r.Method)
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ext.HTTPUrl.Set(sp, r.URL.String())
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// set component name, use "net/http" if caller does not specify
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componentName := opts.componentName
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if componentName == "" {
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componentName = defaultComponentName
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}
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ext.Component.Set(sp, componentName)
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w = &statusCodeTracker{w, 200}
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r = r.WithContext(opentracing.ContextWithSpan(r.Context(), sp))
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h.ServeHTTP(w, r)
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ext.HTTPStatusCode.Set(sp, uint16(w.(*statusCodeTracker).status))
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sp.Finish()
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}
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return http.HandlerFunc(fn)
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}
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