It seems that librenms sessions are stored within the deployment directory in /srv/deployment/librenms/librenms/storage/framework/sessions/. As a result at every puppet run, puppet changes the permission of all the new files, resulting in a very spammy and unnecessary puppet run:
... Notice: /Stage[main]/Librenms/File[/srv/deployment/librenms/librenms/storage/framework/sessions/pYFY...SNIP.../mode: mode changed '0644' to '0660' ...