Configure logback log level via environment variables

If you are running a java application with logback inside a docker container, it may be really useful to interact with logging levels via OS environment variables.

It’s simple as declaring a new variable inside your logback.xml file and provide a default value as in the Bash shell, using the ":-" operator.

<variable name="CLOUDESIRE_LOG_LEVEL" value="${CLOUDESIRE_LOG_LEVEL:-DEBUG}" />
<logger name="com.cloudesire" level="${CLOUDESIRE_LOG_LEVEL}"/>

Then you can simply run your docker container tuning the log level by passing an appropriate value, e.g.: CLOUDESIRE_LOG_LEVEL=WARN.

Source: Developers’ Corner Blog