harvest only 7days old logs by default
diff --git a/metadata/service/server/amqp/shipper.yml b/metadata/service/server/amqp/shipper.yml
index 64fb6c1..2440b4c 100644
--- a/metadata/service/server/amqp/shipper.yml
+++ b/metadata/service/server/amqp/shipper.yml
@@ -13,7 +13,7 @@
           priority: ["^Index"]
           differentiator: [ "rsyslog-", "Service" ]
           decoder: RsyslogDecoder
-          oldest_duration: 7d
+          oldest_duration: "7d"
       decoder:
         rsyslog:
           engine: rsyslog