2016-10-06 17:10:27 +0900 [warn]: temporarily failed to flush the buffer. next_retry=2016-10-06 17:10:28 +0900 error_class="NoMethodError" error="undefined method `[]=' for nil:NilClass" plugin_id="to_kafka"
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluent-plugin-kafka-0.2.2/lib/fluent/plugin/out_kafka_buffered.rb:215:in `block in write'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/buffer.rb:123:in `each'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/buffer.rb:123:in `block in msgpack_each'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/plugin/buf_file.rb:71:in `open'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/buffer.rb:120:in `msgpack_each'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluent-plugin-kafka-0.2.2/lib/fluent/plugin/out_kafka_buffered.rb:210:in `write'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/buffer.rb:354:in `write_chunk'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/buffer.rb:333:in `pop'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/output.rb:338:in `try_flush'
2016-10-06 17:10:27 +0900 [warn]: /home/edge-dev/local/ruby-2.2/lib/ruby/gems/2.2.0/gems/fluentd-0.12.28/lib/fluent/output.rb:149:in `run'
2016-10-06 17:10:28 +0900 [warn]: Send exception occurred: undefined method `[]=' for nil:NilClass
2016-10-06 17:10:28 +0900 [info]: initialized kafka producer: kafka
ちなみに、同じログを受けている別のfluentd (out_forward, out_webhdfs使用)では、以下のような感じのエラーが多数出ていた.
2016-10-06 17:10:08 +0900 [warn]: dump an error event: error_class=NoMethodError error="undefined method `/' for \"POST\":String" tag="sometag" time=1475741408 record={"time"=>"POST", "record"=>nil}