<appender name="sentry" class="net.kencochrane.raven.log4j.SentryAppender">
    <param name="dsn" value="https://xxx:yyy@remote_server_with_sentry/zzz?raven.async.queuesize=100"/>
    <filter class="org.apache.log4j.varia.LevelRangeFilter">
      <param name="levelMin" value="ERROR"/>
    </filter>
  </appender>

log4j:ERROR Could not create an Appender. Reported error follows.
java.lang.ClassNotFoundException: net.kencochrane.raven.log4j.SentryAppender
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:171)
        at org.apache.log4j.helpers.Loader.loadClass(Loader.java:179)
        at org.apache.log4j.xml.DOMConfigurator.parseAppender(DOMConfigurator.java:237)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByName(DOMConfigurator.java:171)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByReference(DOMConfigurator.java:184)
        at org.apache.log4j.xml.DOMConfigurator.parseAppender(DOMConfigurator.java:274)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByName(DOMConfigurator.java:171)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByReference(DOMConfigurator.java:184)
        at org.apache.log4j.xml.DOMConfigurator.parseChildrenOfLoggerElement(DOMConfigurator.java:502)
        at org.apache.log4j.xml.DOMConfigurator.parseRoot(DOMConfigurator.java:471)
        at org.apache.log4j.xml.DOMConfigurator.parse(DOMConfigurator.java:921)
        at org.apache.log4j.xml.DOMConfigurator.doConfigure(DOMConfigurator.java:790)
        at org.apache.log4j.xml.DOMConfigurator.doConfigure(DOMConfigurator.java:682)
        at org.apache.log4j.xml.XMLWatchdog.doOnChange(DOMConfigurator.java:1033)
        at org.apache.log4j.helpers.FileWatchdog.checkAndConfigure(FileWatchdog.java:89)
        at org.apache.log4j.helpers.FileWatchdog.<init>(FileWatchdog.java:58)
        at org.apache.log4j.xml.XMLWatchdog.<init>(DOMConfigurator.java:1025)
        at org.apache.log4j.xml.DOMConfigurator.configureAndWatch(DOMConfigurator.java:662)
        at ru.bitel.common.logging.Log4j.<clinit>(Log4j.java:34)
        at ru.bitel.common.logging.NestedContext.<clinit>(NestedContext.java:32)
        at bitel.billing.server.Server.<init>(Server.java:333)
        at bitel.billing.server.Server.main(Server.java:249)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at ru.bitel.common.bootstrap.Boot.boot(Boot.java:77)
        at ru.bitel.common.bootstrap.Boot.main(Boot.java:125)

   <appender name="ASYNC" class="ru.bitel.common.logging.Log4jAsyncAppender">
      <appender-ref ref="APPLICATION" />
      <appender-ref ref="MQ"/>
      <appender-ref ref="SCRIPT" />
      <appender-ref ref="ERROR" />
   </appender>
   
   <category name="org.apache.fop" additivity="false">
      <priority value="WARN" />
      <appender-ref ref="ASYNC"/>
   </category>
   
   <category name="script" additivity="false">
       <priority value="INFO"/>
       <appender-ref ref="SCRIPT"/>
         <appender-ref ref="ERROR"/>                                                                                                                                                                                                               
    </category>
   
   <category name="server" additivity="false">
       <priority value="INFO"/>                                          
         <appender-ref ref="APPLICATION"/>                                     
         <appender-ref ref="ERROR"/>
    </category>

   <root>
      <priority value="INFO" />
      <appender-ref ref="ASYNC" />
   </root>