我使用的是filebeat->kafka输出连接器，我想根据filebeat正在处理的消息中传递的信息构造hosts和topic参数。
令我惊讶的是，指定完全相同的表达式会导致为主题而不是为hosts字段解析它。对我如何实现目标有什么建议吗？
我的配置如下：

kafka.yaml: |
  processors:
  - add_kubernetes_metadata:
      namespace: {{ .Release.Namespace }}
  # Drop all log lines that don't contain kubernetes.labels.entry field
  - drop_event:
      when:
          not:
            regexp:
              kubernetes.labels.entry: ".*"
  filebeat.config_dir: /conf/
  output.kafka: 
    hosts: '%{[kubernetes][labels][entry]}'
    topic: '%{[kubernetes][labels][entry]}'
    required_acks: 1
    version: 0.11.0.0
    client_id: filebeat
    bulk_max_size: 100
    max_message_bytes: 20480

下面是我从filebeat得到的错误信息：

2018/05/09 01:54:29.805431 log.go:36: INFO Failed to connect to broker [[%{[kubernetes][labels][entry]} dial tcp: address %{[kubernetes][labels][entry]}: missing port in address]]: %!s(MISSING)

我确实尝试将端口添加到上述配置中，但错误消息仍然显示该字段尚未解析：

2018/05/09 02:13:41.392742 log.go:36: INFO client/metadata fetching metadata for all topics from broker [[%{[kubernetes][labels][entry]}:9092]]
2018/05/09 02:13:41.392854 log.go:36: INFO Failed to connect to broker [[%{[kubernetes][labels][entry]}:9092 dial tcp: address %{[kubernetes][labels][entry]}:9092: unexpected '[' in address]]: %!s(MISSING)