use rabbitmq message's header values as metadata values in the binding (#3031)

Signed-off-by: Ohlicher Robert <r.ohlicher@palfinger.com>
Signed-off-by: Alessandro (Ale) Segala <43508+ItalyPaleAle@users.noreply.github.com>
Co-authored-by: Ohlicher Robert <r.ohlicher@palfinger.com>
Co-authored-by: Alessandro (Ale) Segala <43508+ItalyPaleAle@users.noreply.github.com>

bindings/rabbitmq/rabbitmq.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"net/url"
 	"reflect"
 	"strconv"
 	"sync"
@@ -464,8 +465,20 @@ func (r *RabbitMQ) handleMessage(ctx context.Context, handler bindings.Handler,
 				r.logger.Info("Input binding channel closed")
 				return
 			}
+
+			metadata := make(map[string]string, len(d.Headers))
+			// Passthrough any custom metadata to the handler.
+			for k, v := range d.Headers {
+				if s, ok := v.(string); ok {
+					// Escape the key and value to ensure they are valid URL query parameters.
+					// This is necessary for them to be sent as HTTP Metadata.
+					metadata[url.QueryEscape(k)] = url.QueryEscape(s)
+				}
+			}
+
 			_, err := handler(ctx, &bindings.ReadResponse{
-				Data: d.Body,
+				Data:     d.Body,
+				Metadata: metadata,
 			})
 			if err != nil {
 				ch.Nack(d.DeliveryTag, false, true)