Logback Manual

https://logback.qos.ch/manual/
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Logback is a Java logging framework that provides flexible configuration, appenders, encoders,...
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### Start SimpleSSLSocketServer with SSL system properties

Source: https://logback.qos.ch/manual/appenders-network.html

Command to start SimpleSSLSocketServer from the logback-examples directory. Requires port, configFile, and allowedAddress arguments, plus system properties for keystore location and password. The example uses a test X.509 credential; production requires an appropriate credential.

```bash
java -Djavax.net.ssl.keyStore=src/main/java/chapters/appenders/socket/ssl/keystore.jks \
-Djavax.net.ssl.keyStorePassword=changeit \
ch.qos.logback.classic.net.SimpleSSLSocketServer 6000 \
src/main/java/chapters/appenders/socket/ssl/server.xml \
127.0.0.1 ::1
```

--------------------------------

### Run ConfigurationTester with logback-Console.xml

Source: https://logback.qos.ch/manual/appenders-console-file.html

Command to run the ConfigurationTester example with the ConsoleAppender configuration. Requires setting up the class path as described in the setup guide.

```bash
java [chapters.appenders.ConfigurationTester](https://logback.qos.ch/xref/chapters/appenders/ConfigurationTester.html) src/main/java/chapters/appenders/conf/logback-Console.xml
```

--------------------------------

### Start SimpleSSLSocketServer with JSSE keyStore properties

Source: https://logback.qos.ch/manual/usingSSL.html

Command line to start the SimpleSSLSocketServer with JSSE system properties specifying the key store location, password, and type. Note that the keyStore property uses a path, while logback.xml uses a URL.

```bash
java -DkeyStore=/etc/logback-server-keystore.jks \
-DkeyStorePassword=changeit -DkeyStoreType=JKS \
ch.qos.logback.net.SimpleSSLSocketServer 6000 /etc/logback-server-config.xml
```

--------------------------------

### Start SimpleSocketServer with command-line arguments

Source: https://logback.qos.ch/manual/appenders-network.html

Command to start SimpleSocketServer, specifying port 6000, a configuration file, and allowed client addresses (IPv4 and IPv6 loopback). Requires at least one allowed address.

```bash
java ch.qos.logback.classic.net.SimpleSocketServer 6000 \ src/main/java/chapters/appenders/socket/server1.xml \ 127.0.0.1 ::1
```

--------------------------------

### Example log output with pattern header

Source: https://logback.qos.ch/manual/encoders.html

Shows the resulting log file content when outputPatternAsHeader is enabled, with the pattern line starting with '#logback.classic pattern'.

```text
#logback.classic pattern: %d [%thread] %-5level %logger{36} - %msg%n
2012-04-26 14:54:38,461 [main] DEBUG com.foo.App - Hello world
2012-04-26 14:54:38,461 [main] DEBUG com.foo.App - Hi again
...
```

--------------------------------

### Start NumberCruncherServer with mdc1.xml

Source: https://logback.qos.ch/manual/mdc.html

Command to start the NumberCruncherServer with the mdc1.xml configuration file.

```bash
java chapters.mdc.NumberCruncherServer src/main/java/chapters/mdc/mdc1.xml
```

--------------------------------

### Start SimpleSocketServer

Source: https://logback.qos.ch/manual/appenders-network.html

Command to start SimpleSocketServer on port 6000 with server2.xml configuration and allowed addresses 127.0.0.1 and ::1.

```bash
java ch.qos.logback.classic.net.SimpleSocketServer 6000 \
 src/main/java/chapters/appenders/socket/server2.xml \
 127.0.0.1 ::1
```

--------------------------------

### Start client application with JSSE trustStore properties

Source: https://logback.qos.ch/manual/usingSSL.html

Command line to start an application using Logback's SSL-enabled client components with JSSE system properties for the trust store. Note that the trustStore property uses a path, while logback.xml uses a URL.

```bash
java -DtrustStore=/etc/logback-client-truststore.jks \
-DtrustStorePassword=changeit -DtrustStoreType=JKS \
com.example.MyLoggingApplication
```

--------------------------------

### Sample output of %xException with packaging info

Source: https://logback.qos.ch/manual/layouts.html

Example stack trace output from the %xException converter, showing packaging information after each frame.

```text
java.lang.NullPointerException at com.xyz.Wombat(Wombat.;java:57) ~\[wombat-1.3.jar:1.3\] at com.xyz.Wombat(Wombat.;java:76) ~\[wombat-1.3.jar:1.3\] at sun.reflect.NativeMethodAccessorImpl.;invoke0(Native Method) ~\[na:1.5.0\_06\] at sun.reflect.NativeMethodAccessorImpl.;invoke(NativeMethodAccessorImpl.;java:39) ~\[na:1.5.0\_06\] at sun.reflect.DelegatingMethodAccessorImpl.;invoke(DelegatingMethodAccessorImpl.;java:25) ~\[na:1.5.0\_06\] at java.lang.reflect.;Method.invoke(Method.;java:585) ~\[na:1.5.0\_06\] at org.junit.internal.;runners.TestMethod.;invoke(TestMethod.;java:59) \[junit-4.4.jar:na\] at org.junit.internal.;runners.MethodRoadie.;runTestMethod(MethodRoadie.;java:98) \[junit-4.4.jar:na\] ...etc
```

--------------------------------

### Sample output of %rootException

Source: https://logback.qos.ch/manual/layouts.html

Example stack trace output from the %rootException converter, showing root cause first and packaging info.

```text
java.lang.NullPointerException
  at com.xyz.Wombat(Wombat.;java:57) ~[wombat-1.3.jar:1.3]
  at com.xyz.Wombat(Wombat.;java:76) ~[wombat-1.3.jar:1.3]
Wrapped by: org.springframework.;BeanCreationException: Error creating bean with name 'wombat':
  at org.springframework.;AbstractBeanFactory.;getBean(AbstractBeanFactory.;java:248) [spring-2.0.jar:2.0]
  at org.springframework.;AbstractBeanFactory.;getBean(AbstractBeanFactory.;java:170) [spring-2.0.jar:2.0]
  at org.apache.catalina.;StandardContext.;listenerStart(StandardContext.;java:3934) [tomcat-6.0.26.jar:6.0.26]
                    
```

--------------------------------

### Command to run CallerEvaluatorExample

Source: https://logback.qos.ch/manual/layouts.html

Command line invocation to run the Java example with the configuration file as an argument.

```bash
java chapters.layouts.CallerEvaluatorExample src/main/java/chapters/layouts/callerEvaluatorConfig.xml
```

--------------------------------

### Run HelloWorld1 application

Source: https://logback.qos.ch/manual/introduction.html

Command to launch the first sample application. When no default configuration file is found, logback adds a ConsoleAppender to the root logger, producing a single console line.

```bash
java chapters.introduction.HelloWorld1
```

--------------------------------

### Implementing a custom TurboFilter in Java

Source: https://logback.qos.ch/manual/filters.html

Extend the TurboFilter abstract class and implement the decide() method. The example accepts events with a specific marker, returning ACCEPT if the marker matches, otherwise NEUTRAL. The start() method validates the marker option from configuration.

```java
package chapters.filters;

import org.slf4j.Marker;
import org.slf4j.MarkerFactory;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.turbo.TurboFilter;
import ch.qos.logback.core.spi.FilterReply;

public class SampleTurboFilter extends TurboFilter {

  String marker;
  Marker markerToAccept;

  @Override
  public FilterReply decide(Marker marker, Logger logger, Level level,
      String format, Object[] params, Throwable t) {

    if (!isStarted()) {
      return FilterReply.NEUTRAL;
    }

    if ((markerToAccept.equals(marker))) {
      return FilterReply.ACCEPT;
    } else {
      return FilterReply.NEUTRAL;
    }
  }

  public String getMarker() {
    return marker;
  }

  public void setMarker(String markerStr) {
    this.marker = markerStr;
  }

  @Override
  public void start() {
    if (marker != null && marker.trim().length() > 0) {
      markerToAccept = MarkerFactory.getMarker(marker);
      super.start(); 
    }
  }
}
```

--------------------------------

### Sample output from running SampleLogging with mySampleConverterConfig.xml

Source: https://logback.qos.ch/manual/layouts.html

Example output produced by the command 'java chapters.layouts.SampleLogging src/main/java/chapters/layouts/mySampleConverterConfig.xml'. Shows the elapsed nanoseconds, thread, level, and message.

```text
4868695 [main] DEBUG - Everything's going well
5758748 [main] ERROR - maybe not quite...
```

--------------------------------

### Start NumberCruncherClient

Source: https://logback.qos.ch/manual/mdc.html

Command to start the NumberCruncherClient application, where hostname is the host where the server is running.

```bash
java chapters.mdc.NumberCruncherClient hostname
```

--------------------------------

### Basic logback configuration file (sample0.xml)

Source: https://logback.qos.ch/manual/configuration.html

Configuration file equivalent to BasicConfigurator, using a ConsoleAppender with a PatternLayoutEncoder. Place it as logback.xml or logback-test.xml on the class path.

```xml
<configuration>

  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <!-- encoders are assigned the type
         ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
    <encoder>
      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} -%kvp- %msg%n</pattern>
    </encoder>
  </appender>

  <root level="debug">
    <appender-ref ref="STDOUT" />
  </root>
</configuration>
```

--------------------------------

### Install LevelChangePropagator with contextListener

Source: https://logback.qos.ch/manual/configuration-conditional.html

Configures a contextListener to install LevelChangePropagator, which propagates level changes to java.util.logging. The debug attribute is set to true.

```xml
<configuration debug="true">
  <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator"/>
   <!-- rest of the configuration file .... -->
</configuration>
```

--------------------------------

### Install MDCInsertingServletFilter in web.xml

Source: https://logback.qos.ch/manual/mdc.html

Add these filter and filter-mapping elements to your web application's web.xml file to install MDCInsertingServletFilter. Ensure it is declared before other filters so that MDC values are available to them.

```xml
<filter>
  <filter-name>MDCInsertingServletFilter</filter-name>
  <filter-class>
    ch.qos.logback.classic.helpers.MDCInsertingServletFilter
  </filter-class>
</filter>
<filter-mapping>
  <filter-name>MDCInsertingServletFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>
```

--------------------------------

### Nested variable references in properties file (variables2.properties)

Source: https://logback.qos.ch/manual/configuration-variables.html

Example properties file showing value nesting: the 'destination' variable is composed from 'USER_HOME' and 'fileName'. This file is referenced by the variableSubstitution4.xml configuration example.

```properties
USER_HOME=/home/sebastien
fileName=myApp.log
destination=${USER_HOME}/${fileName}
```

--------------------------------

### Run SampleLogging with sampleLayoutConfig.xml

Source: https://logback.qos.ch/manual/layouts.html

Command to run the SampleLogging application from the logback-examples directory, passing the configuration file as the first argument. It logs a debug message followed by an error message.

```shell
java chapters.layouts.SampleLogging src/main/java/chapters/layouts/sampleLayoutConfig.xml
```

--------------------------------

### Basic logging template (HelloWorld1.java)

Source: https://logback.qos.ch/manual/introduction.html

Shows the minimal setup for logging with SLF4J and logback. Imports Logger and LoggerFactory from SLF4J, obtains a logger named 'chapters.introduction.HelloWorld1', and logs a debug message. No logback classes are referenced; only SLF4J API is used.

```java
package chapters.introduction;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class HelloWorld1 {

  public static void main(String[] args) {

    Logger logger = LoggerFactory.getLogger("chapters.introduction.HelloWorld1");
    logger.debug("Hello world.");

  }
}
```

--------------------------------

### AsyncAppender XML configuration example

Source: https://logback.qos.ch/manual/appenders-async-sift.html

Example configuration for AsyncAppender with a FileAppender. It sets up a FILE appender with a pattern encoder and an ASYNC appender referencing it, then attaches the ASYNC appender to the root logger with DEBUG level.

```xml
<configuration>
  <appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>myapp.log</file>
    <encoder>
      <pattern>%logger{35} -%kvp -%msg%n</pattern>
    </encoder>
  </appender>

  <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
    <appender-ref ref="FILE" />
  </appender>

  <root level="DEBUG">
    <appender-ref ref="ASYNC" />
  </root>
    </configuration>
```

--------------------------------

### Sample configuration of RollingFileAppender with SizeBasedTriggeringPolicy

Source: https://logback.qos.ch/manual/appenders-rolling.html

Configuration example showing a RollingFileAppender with FixedWindowRollingPolicy and SizeBasedTriggeringPolicy that triggers rollover when the log file reaches 5MB.

```xml
<configuration>
  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>test.log</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
      <fileNamePattern>test.%i.log.zip</fileNamePattern>
      <minIndex>1</minIndex>
      <maxIndex>3</maxIndex>
    </rollingPolicy>

    <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
      <maxFileSize>5MB</maxFileSize>
    </triggeringPolicy>
    <encoder>
      <pattern>%-4relative [%thread] %-5level %logger{35} -%kvp -%msg%n</pattern>
    </encoder>
  </appender>
	
  <root level="DEBUG">
    <appender-ref ref="FILE" />
  </root>
</configuration>
```

--------------------------------

### Console output of HelloWorld1

Source: https://logback.qos.ch/manual/introduction.html

Example output from running HelloWorld1. Shows the default logback console output format with timestamp, thread, level, logger name, and message.

```text
20:49:07.962 [main] DEBUG chapters.introduction.HelloWorld1 - Hello world.
```

--------------------------------

### Example SSL configuration audit log output

Source: https://logback.qos.ch/manual/usingSSL.html

Example output from SSL audit logging showing protocol, provider, key store, key manager, secure random, enabled protocols, and cipher suites. Truncated for brevity.

```text
06:46:31,941 |-INFO in SSLServerSocketReceiver@4ef18d37 - SSL protocol 'SSL' provider 'SunJSSE version 1.6'
06:46:31,967 |-INFO in SSLServerSocketReceiver@4ef18d37 - key store of type 'JKS' provider 'SUN version 1.6': file:src/main/java/chapters/appenders/socket/ssl/keystore.jks
06:46:31,967 |-INFO in SSLServerSocketReceiver@4ef18d37 - key manager algorithm 'SunX509' provider 'SunJSSE version 1.6'
06:46:31,973 |-INFO in SSLServerSocketReceiver@4ef18d37 - secure random algorithm 'SHA1PRNG' provider 'SUN version 1.6'
06:46:32,755 |-INFO in SSLParametersConfiguration@4a6f19d5 - enabled protocol: SSLv2Hello
06:46:32,755 |-INFO in SSLParametersConfiguration@4a6f19d5 - enabled protocol: SSLv3
06:46:32,755 |-INFO in SSLParametersConfiguration@4a6f19d5 - enabled protocol: TLSv1
06:46:32,756 |-INFO in SSLParametersConfiguration@4a6f19d5 - enabled cipher suite: SSL_RSA_WITH_RC4_128_MD5
06:46:32,756 |-INFO in SSLParametersConfiguration@4a6f19d5 - enabled cipher suite: SSL_RSA_WITH_RC4_128_SHA
06:46:32,756 |-INFO in SSLParametersConfiguration@4a6f19d5 - enabled cipher suite: TLS_RSA_WITH_AES_256_CBC_SHA
```

--------------------------------

### GenericXMLConfigurator.doConfigure pipeline steps

Source: https://logback.qos.ch/manual/onJoran.html

Shows the core steps of the configuration pipeline: recording SAX events, building a model, sanity checking, and processing the model. This is the rough sequence used by GenericXMLConfigurator.doConfigure in logback 1.3.

```java
SaxEventRecorder recorder = populateSaxEventRecorder(inputSource);
Model topModel = buildModelFromSaxEventList(recorder.getSaxEventList());
sanityCheck(topModel);
processModel(topModel);  // DefaultProcessor + model handlers
```

--------------------------------

### TrivialLogbackAppender - logback version

Source: https://logback.qos.ch/manual/migrationFromLog4j.html

The logback-classic equivalent of the trivial appender. It extends AppenderBase and overrides start and append. The start method checks for a layout and logs an error if missing. The append method uses the layout to format the event and writes to the console.

```java
package chapters.migrationFromLog4j;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.AppenderBase;

public class TrivialLogbackAppender extends AppenderBase<ILoggingEvent> {

  @Override
  public void start() {
    if (this.layout == null) {
      addError("No layout set for the appender named [" + name + "].");
      return;
    }
    super.start();
  }

  @Override
  protected void append(ILoggingEvent loggingevent) {
    // note that AppenderBase.doAppend will invoke this method only if
    // this appender was successfully started.
    
    String s = this.layout.doLayout(loggingevent);
    System.out.println(s);
  }
}
```
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