${my.property:-default} style defaults defined in logback.xml do not work

[ppalaga]

I wanted to add something like the following to logback.xml, but it does not work

  <!-- Allow increasing mvnd log level from command line -->
  <logger name="org.jboss.fuse.mvnd" level="${mvnd.log.level:-INFO}" />

With the above setting and -Dmvnd.log.level=DEBUG passed via CLI, the log level is not set to DEBUG.

When I change it to

  <logger name="org.jboss.fuse.mvnd" level="${mvnd.log.level}" />

-Dmvnd.log.level=DEBUG works as expected, but building without -Dmvnd.log.level=DEBUG (as expected per logback docs) leads to org.jboss.fuse.mvnd being set to DEBUG anyway, which is not nice.

[gnodet]

That may have been fixed by 59a9bba

[gnodet]

I found what is happening. The daemon JVM is launched first without any specific system properties from the command line, so when the logback configuration is loaded, the mvnd.log.level is not set.
The workaround is to use mvnd.jvmArgs="-Dmvnd.log.level=DEBUG" in one of the mvnd.properties file or on the command line using -Dmvnd.jvmArgs="-Dmvnd.log.level=DEBUG". Note that the mvnd.jvmArgs is a discriminating property, so a specific daemon will be created.