logstash-output-loki

alternative logstash-output-loki plugin fixed json format problem

inspired by grafana/loki#4863

"line" => event.get(message_field).to_s => "line" => JSON.generate(event.get(message_field))

output{
  url => "http://loki:3100/loki/api/v1/push"
  json => true
}