[14:29:23] <tgr>	 bd808: do you know whether https://gerrit.wikimedia.org/r/c/mediawiki/core/+/608057/1/includes/HeaderCallback.php#53 is the kind of thing that would break logstash?
[15:11:40] <bd808>	 tgr: unless something has changed, yes. If an ES schema has a field typed as a scalar and then you send the same field as a collection, the collection containing document will be rejected. That was the behavior change that made ES useless for log aggregation IMO. 
[15:12:54] <bd808>	 It actually even effects scalars of different types, but you can tweak the schema to auto coerce.
[15:25:15] <tgr>	 bd808: thanks! is there a workaround for that? (I seem to remember people deleting logstash indexes) or is it best to just rename the field?
[15:46:59] <bd808>	 tgr: each day starts a new shard with its own schema, so yes it is possible to work around with a purge of the current shard and deleting its schema. Using a new label for the field is less disruptive