打算下载flink程序的日志看看，发现报错：

yarn application -list -appStates ALL |grep Flink

yarn logs -applicationId application_1554280683684_749610

Log aggregation has not completed or is not enabled.

解决：yarn-site.xml 配置文件中少配置了一项

<property>

      <description>Whether to enable log aggregation</description>

      <name>yarn.log-aggregation-enable</name>

      <value>true</value>

  </property>