Full MVC of gitlab-zoekt-indexer

cmd/gitlab-zoekt-indexer/correlation.go

+package main
+
+import (
+	"context"
+	"net/http"
+
+	"gitlab.com/gitlab-org/labkit/correlation"
+)
+
+// Key to use when setting the request ID.
+type ctxKeyRequestID int
+
+// RequestIDKey is the key that holds the unique request ID in a request context.
+const (
+	RequestIDHeader                 = "X-Request-Id"
+	RequestIDKey    ctxKeyRequestID = 0
+)
+
+func correlationIDMiddleware(next http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+		requestID := r.Header.Get(RequestIDHeader)
+		if requestID == "" {
+			requestID = correlation.SafeRandomID()
+		}
+
+		ctx = context.WithValue(ctx, RequestIDKey, requestID)
+		next.ServeHTTP(w, r.WithContext(ctx))
+	}
+	return http.HandlerFunc(fn)
+}
+
+func getCorrelationID(ctx context.Context) string {
+	if ctx == nil {
+		return ""
+	}
+	if reqID, ok := ctx.Value(RequestIDKey).(string); ok {
+		return reqID
+	}
+	return ""
+}