Remove header information added by logstash

Elastic Stack Logstash
5

Here is the ruby code that that warning log message is coming from:

        begin
          client_socket = connect unless client_socket
          r,w,e = IO.select([client_socket], [client_socket], [client_socket], nil)
          # don't expect any reads, but a readable socket might
          # mean the remote end closed, so read it and throw it away.
          # we'll get an EOFError if it happens.
          client_socket.sysread(16384) if r.any?

          # Now send the payload
          client_socket.syswrite(payload) if w.any?
        rescue => e
          @logger.warn("tcp output exception", :host => @host, :port => @port,
                       :exception => e, :backtrace => e.backtrace)
          client_socket.close rescue nil
          client_socket = nil
          sleep @reconnect_interval
          retry
        end

This seems to mean that the remote end closed early and we sleep and retry at the default reconnect_interval of 10 seconds.
I suggest that you investigate the network activity, correct the problem and reduce the reconnect_interval to 1 second.