Custom Log Configurations

If the preconfigured logging styles do not meet your requirements, you can customize the logging configuration. To do so, prepare an external configuration file and specify the path to that file in an environment variable ($LOGGING_CONFIGURATION).

Documentation for logback appenders can be found here: https://logback.qos.ch/manual/appenders.html

To construct the external configuration file, extract a logback configuration from the flexnetls.jar file and modify it to suit your requirements. The following tables shows the existing configurations.


Logging Style	Extraction Command
CONTINUOUS	unzip -p flexnetls.jar BOOT-INF/classes/logback-continuous.xml
CONTINUOUS_UTC	unzip -p flexnetls.jar BOOT-INF/classes/logback-continuous.xml
DAILY_ROLLOVER	unzip -p flexnetls.jar BOOT-INF/classes/logback-rollover.xml
DAILY_ROLLOVER_UTC	unzip -p flexnetls.jar BOOT-INF/classes/logback-rollover.xml
JSON	unzip -p flexnetls.jar BOOT-INF/classes/logback.xml
JSON_ROLLOVER	unzip -p flexnetls.jar BOOT-INF/classes/logback-rollover-json.xml

Note:The "_UTC" variants share a configuration file with their local time counterpart, as the difference is expressed in a "logging.timestamp" system property.

Filtering Log Messages

If your custom logback configuration needs to suppress specific log messages, you can use the MessageContainsEvaluator filter. This is useful, for example, to prevent recurring warning messages (such as "Incompatible or syntactically incorrect IP addresses") from filling your log files.

Add the following filter block inside each <appender> element in your custom logback XML file where you want to suppress the message:

<expression>Incompatible or syntactically incorrect IP addresses</expression>

</evaluator>

<OnMismatch>NEUTRAL</OnMismatch>

</filter>

Replace the <expression> value with the text of the message you want to suppress. The filter matches any log message that contains the specified text.

To see how this filter is used in context, you can extract the sample logback XML files included in the flexnetls.jar file (located in the server directory). For example:

unzip -p flexnetls.jar BOOT-INF/classes/logback-rollover.xml

Note:If you are upgrading from a version prior to 2026.06 and your custom logback configuration uses the older Janino-based EvaluatorFilter syntax (with return message.contains("...");), you must update to the new syntax shown above. The older Janino JaninoEventEvaluator is no longer supported.