By default, Metabase logs quite a bit of information. Luckily, Metabase uses Log4j under the hood, meaning the logging is completely configurable.
Metabase's default logging configuration can be found here. You can override this properties file and tell
Metabase to use your own logging configuration file by passing a -Dlog4j.configuration argument when running Metabase:
java -Dlog4j.configuration=file:/path/to/custom/log4j.properties -jar metabase.jar
The easiest way to get started customizing logging would be to use a copy of default log4j.properties file linked to above and adjust that to meet your needs. Keep in mind that you'll need to restart Metabase for changes to the file to take effect.
By default Metabase will include emoji characters in logs. You can disable this by using the following environment variable:
export MB_EMOJI_IN_LOGS="false"
java -jar metabase.jar