55 lines
1.2 KiB
Go
55 lines
1.2 KiB
Go
package rest
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import (
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"context"
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"crypto/rand"
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"crypto/sha1"
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"fmt"
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"net/http"
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"time"
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)
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type contextKey string
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const traceHeader = "X-Request-ID"
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// Trace looks for header X-Request-ID and makes it as random id if not found, then populates it to the result's header
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// and to request context
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func Trace(next http.Handler) http.Handler {
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fn := func(w http.ResponseWriter, r *http.Request) {
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traceID := r.Header.Get(traceHeader)
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if traceID == "" {
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traceID = randToken()
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}
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w.Header().Set(traceHeader, traceID)
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ctx := context.WithValue(r.Context(), contextKey("requestID"), traceID)
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r = r.WithContext(ctx)
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next.ServeHTTP(w, r)
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}
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return http.HandlerFunc(fn)
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}
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// GetTraceID returns request id from the context
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func GetTraceID(r *http.Request) string {
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if id, ok := r.Context().Value(contextKey("requestID")).(string); ok {
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return id
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}
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return ""
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}
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func randToken() string {
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fallback := func() string {
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return fmt.Sprintf("%x", time.Now().Nanosecond())
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}
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b := make([]byte, 32)
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if _, err := rand.Read(b); err != nil {
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return fallback()
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}
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s := sha1.New()
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if _, err := s.Write(b); err != nil {
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return fallback()
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}
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return fmt.Sprintf("%x", s.Sum(nil))
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}
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