JSON filter gives warning that it requires a target

arisbanach · January 6, 2018, 2:47pm

[2018-01-06T03:41:04,492][WARN ][logstash.filters.json ] Parsed JSON object/hash requires a target configuration option {:source=>"extras", :raw=>""}

I don't have a target set because I read in the documentation that the default behavior is to put the parsed fields at the top level of the doc. Why is it warning me about this then? The warning barely ever shows up, even though it has successfully parsed that field in millions of other docs.

magnusbaeck · January 6, 2018, 4:30pm

It looks like the string you're attempting to parse is empty (note :raw=>"").

arisbanach · January 6, 2018, 6:22pm

Why does the error say it needs a target then? Shouldn't the error say "trying to parse empty string" or something?

magnusbaeck · January 6, 2018, 9:13pm

Parsing an empty string apparently results in a valid value (in the sense that the parsing doesn't fail), but since it's not a hash you get the generic error message in question.

github.com

logstash-plugins/logstash-filter-json/blob/v3.0.5/lib/logstash/filters/json.rb#L88-L92


unless parsed.is_a?(Hash)
  @tag_on_failure.each{|tag| event.tag(tag)}
  @logger.warn("Parsed JSON object/hash requires a target configuration option", :source => @source, :raw => source)
  return
end

system · February 3, 2018, 9:13pm

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