Modifying an arrays value by index

[Fabio-sama (Fabio)]

I'd refactor your code as following

filter {
  ruby {
    code => '
      hash = event.get("kv")
      event.get("template").each_with_index do |item, index|
        hash.each { |k, v| event.set("[template][#{index}]", v) if k.include? "id" }
      end
    '
  }
}