set default log dir to 'logs'

pdb-ui/src/main/resources/log4j2.xml

@@ -1,13 +1,18 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Configuration
 	monitorInterval="10">
+	
+  <Properties>
+    <Property name="LOG_DIR">${sys:logDir:-logs}</Property>
+  </Properties>
+
   <Appenders>
     <Console name="Console" target="SYSTEM_OUT">
       <PatternLayout pattern="%d %5p [%-20.20t] %-30.30c{1.} : %m%n"/>
     </Console>
     <RollingRandomAccessFile name="logfile" 
-            fileName="${sys:logDir}/pdb.log" 
-            filePattern="${sys:logDir}/pdb.%d{yyyy-MM-dd_HHmmss}.log.zip">
+            fileName="${LOG_DIR}/pdb.log" 
+            filePattern="${LOG_DIR}/pdb.%d{yyyy-MM-dd_HHmmss}.log.zip">
             <PatternLayout pattern="%d %5p [%-20.20t] %-30.30c{1.} : %m%n"
                            charset="UTF-8"/>
             <Policies>
@@ -15,7 +20,7 @@
                 <CronTriggeringPolicy schedule="0 0 0 * * ?"/><!-- triggers every day at midnight -->
             </Policies>
 			<DefaultRolloverStrategy>
-				<Delete basePath="${sys:logDir}" maxDepth="1">
+				<Delete basePath="${LOG_DIR}" maxDepth="1">
 					<IfFileName glob="*/pdb.*.log.zip" />
 					<IfLastModified age="30d" />
 				</Delete>