How to configure custom PatternLayout of a LoggingEventCompositeJsonEncoder?

Question

i have created a custom PatternLayout i'm using in Access and File appenders of logback, and I would like to use it as well for a LoggingEventCompositeJsonEncoder.

Is it possible to configure the encoder with my layout, and how can i achieve this ?

Exemple of the file appender configuration :

<appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
   <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
      <layout class="com.me.util.logging.PatternLayoutFiltered">
      <pattern>${LOG_PATTERN}</pattern>
      </layout>
   </encoder>
   <file>${LOG_FILE}</file>
   <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <!-- rotate every day -->
      <fileNamePattern>${logback.rollingPolicy.file.fileNamePattern}</fileNamePattern>
      <!-- Days of history -->
      <maxHistory>${logback.maxHistory.retention:-7}</maxHistory>
   </rollingPolicy>
</appender>

My logstash encoder :

<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
   <providers>
      <timestamp>%d{ISO8601}</timestamp>
      <message/>
      <loggerName/>
      <context/>
      <mdc/>
      <pattern>
         <pattern>
            {
            "appVersion": "${build.version}",
            "appName": "${build.artifact}",
            "resourceType": "${logback.application.resource.type}",
            "resourceID": "${logback.application.resource.id}",
            "level": "%level",
            "hostname": "${logback.server.host}",
            "indexType": "${logback.logstash.index.type}"
            }
         </pattern>
         </layout>
      </pattern>
      <stackTrace/>
   </providers>
</encoder>

Where can i define the same PatternLayout here ? I've read here that

Every value in the template is treated as a pattern for logback's standard PatternLayout so it can be a combination of literal strings (for some constants) and various conversion specifiers (like %d for date).

So how i can configure my own ? Thanks for your help.

Answer 1

Well to solve this, i had to use a custom valueMasker to do the filtering, and apply the same filtering method than my layout to filter the field value.

Added to logback.xml :

<jsonGeneratorDecorator class="net.logstash.logback.mask.MaskingJsonGeneratorDecorator">
    <valueMasker class="com.me.util.logging.CustomValueMasker"/></jsonGeneratorDecorator>

Java class is something like :

package com.me.util.logging;

import com.fasterxml.jackson.core.JsonStreamContext;
import net.logstash.logback.mask.ValueMasker;

public class CustomValueMasker implements ValueMasker {

   @Override
   public Object mask(JsonStreamContext jsonStreamContext, Object o) {
      if (o instanceof CharSequence) {
         return doTransform((String) o);
      }
      return o;
   }

   /**
    * Do the message filtering
    *
    * @param msg the message of the event log
    *
    * @return the filtered message
    */
   private String doTransform(String msg) {
      // Do whatever filtering needed here
      return msg;
   }
}