springboot 启动提示WARN No Root logger was configured, creating default ERROR-level Root logger with Console appender

这句日志是Spring Boot应用在启动时，日志系统检测到没有配置根日志记录器时打印的警告信息。在Spring Boot中，默认使用的是SLF4J与Logback作为日志门面和日志实现。如果没有显式地配置日志系统，Logback将创建一个默认的日志配置。

这个默认配置将设置一个根日志记录器(root logger)，它具有ERROR级别的日志级别，并且将错误日志输出到控制台(console appender)。这意味着在没有其他更细粒度的日志配置的情况下，你的应用只会记录ERROR级别以上的日志，并且只能在控制台看到这些错误信息。

为了避免这种情况，通常建议在应用的配置文件（例如`application.properties`或`application.yml`）中添加适当的日志配置。例如，你可以在`application.properties`文件中添加以下内容来指定日志级别和输出文件：

logging.level.root=INFO
logging.path=/path/to/log/directory
logging.file=myapp.log

这里的`logging.level.root=INFO`将根日志记录器的级别设置为INFO，而`logging.path`和`logging.file`指定了日志文件的存储位置和文件名。

相关问题

WARN No appenders could be found for logger (org.thymeleaf.TemplateEngine).

This warning message indicates that the Thymeleaf template engine was unable to find any configured logging appenders for its internal logging system. This means that any log messages generated by the template engine will not be outputted to any logging destinations.

To resolve this issue, you need to configure an appender for the logger in your logging framework (e.g. log4j, logback). You can do this by adding an appender configuration to your logging configuration file and specifying the appender class and destination (e.g. file, console).

Here is an example configuration for logback:

<configuration>
  <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n</pattern>
    </encoder>
  </appender>
  <logger name="org.thymeleaf.TemplateEngine" level="DEBUG">
    <appender-ref ref="console" />
  </logger>
</configuration>

This configuration sets up a console appender for the logger with the name "org.thymeleaf.TemplateEngine". Any log messages generated by this logger will be outputted to the console. You can customize the appender class and destination to suit your needs.

log4j:WARN No appenders could be found for logger (org.apache.flume.node.PollingPropertiesF

log4j:WARN No appenders could be found for logger (org.apache.flume.node.PollingPropertiesFileConfigurationProvider).
This warning message indicates that the log4j framework was unable to find any appenders configured for the specified logger. An appender is responsible for outputting log messages to a specific destination, such as a file, console, or database.

To resolve this issue, you need to configure an appender for the logger mentioned in the warning message. This can be done by adding an appropriate appender configuration to your log4j configuration file. The configuration file is typically named log4j.properties or log4j.xml and should be present in your application's classpath.

Here is an example of a basic appender configuration for writing logs to a file:

log4j.rootLogger=INFO, file

log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=/path/to/log/file.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

In this example, the `log4j.rootLogger` sets the logging level to INFO and associates it with the `file` appender. The `file` appender is configured to write logs to the specified file path (`/path/to/log/file.log`) using the specified layout pattern.

Make sure to adjust the file path and other settings according to your requirements. Once you have added the appender configuration, restart your application, and the warning should no longer appear.