Exclude eventv1.MetaTokenKey from event metadata

eventv1.MetaTokenKey is required to be considered in rate limiting but
it is only for internal use by flux components and should not be sent to
the alert provider. Remove eventv1.MetaTokenKey from the metadata of
event before processing the event for various matching alerts.

Signed-off-by: Sunny <darkowlzz@protonmail.com>

internal/server/event_handlers.go

@@ -58,6 +58,9 @@ func (s *EventServer) handleEvent() func(w http.ResponseWriter, r *http.Request)
 		ctx, cancel := context.WithTimeout(r.Context(), 15*time.Second)
 		defer cancel()
 
+		// Remove any internal metadata before further processing the event.
+		excludeInternalMetadata(event)
+
 		alerts, err := s.getAllAlertsForEvent(ctx, event)
 		if err != nil {
 			eventLogger.Error(err, "failed to get alerts for the event")
@@ -440,3 +443,14 @@ func (s *EventServer) enhanceEventWithAlertMetadata(ctx context.Context, event *
 		event.Metadata = meta
 	}
 }
+
+// excludeInternalMetadata removes any internal metadata from the given event.
+func excludeInternalMetadata(event *eventv1.Event) {
+	if len(event.Metadata) == 0 {
+		return
+	}
+	excludeList := []string{eventv1.MetaTokenKey}
+	for _, key := range excludeList {
+		delete(event.Metadata, key)
+	}
+}

internal/server/event_handlers_test.go

@@ -1058,3 +1058,35 @@ func TestEnhanceEventWithAlertMetadata(t *testing.T) {
 		})
 	}
 }
+
+func Test_excludeInternalMetadata(t *testing.T) {
+	tests := []struct {
+		name         string
+		event        eventv1.Event
+		wantMetadata map[string]string
+	}{
+		{
+			name: "no metadata",
+		},
+		{
+			name: "internal metadata",
+			event: eventv1.Event{
+				Metadata: map[string]string{
+					eventv1.MetaTokenKey:    "aaaa",
+					eventv1.MetaRevisionKey: "bbbb",
+				},
+			},
+			wantMetadata: map[string]string{
+				eventv1.MetaRevisionKey: "bbbb",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			excludeInternalMetadata(&tt.event)
+			g.Expect(tt.event.Metadata).To(BeEquivalentTo(tt.wantMetadata))
+		})
+	}
+}