Report from Marcel:
We've recently observed that EventLogging's schema MultimediaViewerNetworkPerformance is receiving some events that fail validation with the error:
Additional properties are not allowed (u'varnish4hits', u'varnish4' were unexpected)
It seems that the client that sends the events is adding some fields that are not registered in the schema. Is that possible?
We receive around 260 events per hour that share that same error. I'm not sure if that's a relevant share of them or can be neglected.
BTW, you can see the errors easily in Logstash:
Looking at the code there is indeed a problem, with those fields being added and which are missing from the schema definition.