Fluentd api key를 사용해서 elasticsearch 접속시, 401 에러

에러

Could not communicate to Elasticsearch, resetting connection and trying again. [401] {"error":{"root_cause":[{"type":"security_exception","reason":"unable to authenticate with provided credentials and anonymous access is not allowed for this request","additional_unsuccessful_credentials":"API key: invalid ApiKey value","header":{"WWW-Authenticate":["Basic realm=\"security\" charset=\"UTF-8\"","ApiKey"]}}],"type":"security_exception","reason":"unable to authenticate with provided credentials and anonymous access is not allowed for this request","additional_unsuccessful_credentials":"API key: invalid ApiKey value","header":{"WWW-Authenticate":["Basic realm=\"security\" charset=\"UTF-8\"","ApiKey"]}},"status":401}

api 전달하는 방식 변경: custom_headers 이게 중요함

# 수정전
<match test>
  @type elasticsearch
  # Specify your Elasticsearch host and port.
  host [도메인]
  port [포트]
  scheme [http || https]
  api_key [api key]
</match>

# 수정후
<match test>
  @type elasticsearch
  # Specify your Elasticsearch host and port.
  host [도메인]
  port [포트]
  scheme [http || https]
  custom_headers {"Authorization": "ApiKey [apk key]"}
</match>