title: Print stacktrace with Log4j2 in JSON with JSONLayout in a single line
body: <p>I'm tryting to configure JsonLayaout with Log4j2. I would like to have the stacktrace in just one message in the JSON. I understand that I have to use the attribute "complete".</p>
  
  <p>The example class that I have created is:</p>
  
  <pre><code>public class MyApp {
  
  private static final Logger logger = LogManager.getLogger(MyApp.class);
  
      public static void main(final String... args) {   
          logger.debug("Entering application.");
  
          try{
              int i = 0;
              int a = 5 / i;
          }catch(Exception e){
              //StringWriter sw = new StringWriter();
              //e.printStackTrace(new PrintWriter(sw));
              //String exceptionAsString = sw.toString();    
              logger.error(exceptionAsString);
          }
      }
  }
  </code></pre>
  
  <p>The the log4j2.properties is:</p>
  
  <pre><code>name=PropertiesConfig
  property.filename = logs
  appenders = file, console
  appender.console.type = Console
  appender.console.name = STDOUT
  appender.console.layout.type = JSONLayout
  appender.console.layout.complete="false"
  #appender.console.layout.compact = true
  #appender.console.layout.pattern = [%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n
  appender.file.type = File
  appender.file.name = LOGFILE
  appender.file.fileName=/var/tmp/propertieslogs.log
  appender.file.layout.type=JSONLayout
  appender.file.layout.complete="true"
  #appender.file.layout.pattern=[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n
  
  rootLogger.level = debug
  rootLogger.appenderRefs = stdout, logfile
  rootLogger.appenderRef.stdout.ref = STDOUT
  rootLogger.appenderRef.logfile.ref = LOGFILE
  </code></pre>
  
  <p>The output I'd like it:</p>
  
  <pre><code>[
    {
      "logger":"com.foo.Bar",
      "timestamp":"1376681196470",
      "level":"INFO",
      "threadId":1,
      "thread":"main",
      "threadPriority":1,
      "message":"Message flushed with immediate flush=true"
    },
    {
      "logger":"com.foo.Bar",
      "timestamp":"1376681196471",
      "level":"ERROR",
      "threadId":1,
      "thread":"main",
      "threadPriority":1,
      "message":"Message flushed with immediate flush=true",
      "throwable":"java.lang.IllegalArgumentException: badarg\\n\\tat org.apache.logging.log4j.core.appender.JSONCompleteFileAppenderTest.testFlushAtEndOfBatch(JSONCompleteFileAppenderTest.java:54)\\n\\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\\n\\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)\\n\\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\\n\\tat java.lang.reflect.Method.invoke(Method.java:606)\\n\\tat org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)\\n\\tat org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)\\n\\tat org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)\\n\\tat org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)\\n\\tat org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)\\n\\tat org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)\\n\\tat org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)\\n\\tat org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)\\n\\tat org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)\\n\\tat org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)\\n\\tat org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)\\n\\tat org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)\\n\\tat org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)\\n\\tat org.junit.runners.ParentRunner.run(ParentRunner.java:309)\\n\\tat org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)\\n\\tat org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)\\n\\tat org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)\\n\\tat org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)\\n\\tat org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)\\n\\tat org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)\\n"
    }
  ]
  </code></pre>
  
  <p>But I get:</p>
  
  <pre><code>{
    "timeMillis" : 1474362834903,
    "thread" : "main",
    "level" : "ERROR",
    "loggerName" : "test.MyApp",
    "message" : "Exception:",
    "thrown" : {
      "commonElementCount" : 0,
      "localizedMessage" : "/ by zero",
      "message" : "/ by zero",
      "name" : "java.lang.ArithmeticException",
      "extendedStackTrace" : [ {
        "class" : "test.MyApp",
        "method" : "main",
        "file" : "MyApp.java",
        "line" : 24,
        "exact" : true,
        "location" : "classes/",
        "version" : "?"
      }, {
        "class" : "sun.reflect.NativeMethodAccessorImpl",
        "method" : "invoke0",
        "file" : "NativeMethodAccessorImpl.java",
        "line" : -2,
        "exact" : false,
        "location" : "?",
        "version" : "1.8.0_91"
      }, {
        "class" : "sun.reflect.NativeMethodAccessorImpl",
        "method" : "invoke",
        "file" : "NativeMethodAccessorImpl.java",
        "line" : 62,
        "exact" : false,
        "location" : "?",
        "version" : "1.8.0_91"
      }, {
        "class" : "sun.reflect.DelegatingMethodAccessorImpl",
        "method" : "invoke",
        "file" : "DelegatingMethodAccessorImpl.java",
        "line" : 43,
        "exact" : false,
        "location" : "?",
        "version" : "1.8.0_91"
      }, {
        "class" : "java.lang.reflect.Method",
        "method" : "invoke",
        "file" : "Method.java",
        "line" : 498,
        "exact" : false,
        "location" : "?",
        "version" : "1.8.0_91"
      }, {
        "class" : "com.intellij.rt.execution.application.AppMain",
        "method" : "main",
        "file" : "AppMain.java",
        "line" : 147,
        "exact" : true,
        "location" : "idea_rt.jar",
        "version" : "?"
      } ]
    },
    "endOfBatch" : false,
    "loggerFqcn" : "org.apache.logging.log4j.spi.AbstractLogger",
    "threadId" : 1,
    "threadPriority" : 5
  }
  </code></pre>
  
  <p>Should I build an String to the message as I do in the code or how could I complete the throwable attribute in the log with all the stacktrace?</p>
  
  <p>If I use this code:</p>
  
  <pre><code>   public static void main(final String... args) {
  
          // Set up a simple configuration that logs on the console.
          logger.debug("Entering application.");
  
          try{
              int i = 0;
              int a = 5 / i;
          }catch(Exception e){
              StringWriter sw = new StringWriter();
              e.printStackTrace(new PrintWriter(sw));
              String exceptionAsString = sw.toString();
  
              logger.error(exceptionAsString);
          }
      }
  }
  </code></pre>
  
  <p>I get almost which I want to:</p>
  
  <pre><code>{
    "timeMillis" : 1474542115319,
    "thread" : "main",
    "level" : "DEBUG",
    "loggerName" : "MyApp",
    "message" : "Entering application.",
    "endOfBatch" : false,
    "loggerFqcn" : "org.apache.logging.log4j.spi.AbstractLogger",
    "contextMap" : [ ]
  }{
    "timeMillis" : 1474542115573,
    "thread" : "main",
    "level" : "ERROR",
    "loggerName" : "MyApp",
    "message" : "java.lang.ArithmeticException: / by zero\n\tat MyApp.main(MyApp.java:23)\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\n\tat java.lang.reflect.Method.invoke(Method.java:498)\n\tat com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)\n",
    "endOfBatch" : false,
    "loggerFqcn" : "org.apache.logging.log4j.spi.AbstractLogger",
    "contextMap" : [ ]
  }
  </code></pre>
  
  <p>But, I guess that I could do it automatically without parse the stacktrace to String. </p>