[logback-user] Error when <Property> name and value attributes are present, but value attribute is empty ("")

Shane Kelly logback at ballinascreen.com
Sat Dec 15 19:37:52 CET 2012


I define a number of locally scoped properties in my logback configuration
which are reused throughout the remainder of the file. For example:

<property name="LOG_DATE_FORMAT" value="'yyyy-MM-dd HH:mm:ss,SSS Z'" />
<property name="LOG_TIMEZONE" value="" />
<property name="LOG_BASEDIR" value="${catalina.base}/logs/myappname" />


  <appender name="MyAppName-RFA"

    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">

      <!-- Monthly Rollover, 24 Month Retention -->


      <pattern>%d{${LOG_DATE_FORMAT},${LOG_TIMEZONE}} %-6p
[%X{MyAppName-UUID}] %c:%M - %m%n</pattern>

I have multiple rolling file appenders, so rather than define the values
manually for each appender, I define the local property and reuse as

However, by default the LOG_TIMEZONE value is empty - I only want this
value to be populated when a specific timezone is required. However, as a
result of defining this property but specifying no value I get the
following error message at startup:

18:30:41,402 |-ERROR in ch.qos.logback.core.joran.action.PropertyAction -
In <property> element, either the "file" attribute alone, or the "resource"
element alone, or both the "name" and "value" attributes must be set.

I assume from this error message that a property cannot have a NULL/empty
value - i.e. this is expected behaviour? I guess I could remove/comment the
property if it is not being used in the current configuration - although
I'd rather not remove it from the configuration file completely, since its
presence also acts as a visual reminder of which properties can be set.


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