Develop Reference

Redirect logging from Tomcat to my file (logback)

I use Tomcat 8 and logback on Windows. I configured my logback.xml this way:
<configuration>
<appender name="FILE" class="ch.qos.logback.core.FileAppender">
<file>logging.log</file>
<param name="Append" value="false" />
<encoder>
<pattern>%date %level [%thread] %logger{10} [%file:%line] %msg%n</pattern>
</encoder>
</appender>
<root level="info">
<appender-ref ref="FILE" />
</root>
My pom.xml if neccessary:
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.2.11</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.11</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.36</version>
<scope>compile</scope>
</dependency>
When I started app with public static void main, everything was logging to my logging.log file in the project properly.
However when I started booting my app with Apache Tomcat 8, is has embedded logging (example is on the picture):
Tomcat embedded logging
So my logging.log file keeps empty. How to redirect all the logs back to it?

Tomcat uses different logging mechanism - JULI. What you want to do, is to add jul-to-slf4j bridge. See https://www.slf4j.org/legacy.html#jul-to-slf4j.

I just found out how silly my question was.
Answer is that Tomcat just changes project root location for logging to &CATALINA_HOME&\bin (in my case C:\apache-tomcat-8.5.81\bin).
The file logging.log was created in that directory and has been correctly logging all this time. Meanwhile I was into a stupor because of empty logging.log in my project directory.
Solution is just to describe the absolute path for the logging file in logback.xml:
<file>C:\Users\cognosce\Desktop\myproject\logging.log</file>

log4jdbc-spring-boot-starter is unable to generate log messages

Spring Boot version : 2.3.5
log4jdbc version : 2.0.0
Hibernate version : 5.4.22 (pulled in by the Spring Boot Starter pack)
I am trying to capture SQL query execution related data from our Spring Boot Java application. Following are the changes I have made in our application:
pom.xml -->
<dependency>
<groupId>com.integralblue</groupId>
<artifactId>log4jdbc-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
application.properties -->
log4jdbc.drivers=oracle.jdbc.OracleDriver
log4jdbc.auto.load.popular.drivers=false
log4jdbc.debug.stack.prefix=^com\.myapp\.subpackage.*
log4jdbc.sqltiming.warn.threshold=25
log4jdbc.jdbc.sqltiming.level=DEBUG
log4jdbc.jdbc.sqltiming.logging.file=${application.logging.path}/log4jdbc.log
logback-spring.xml -->
<springProperty name="LOG4JDBC_SQLTIMING_LOGGING_FILE_NAME" source="log4jdbc.jdbc.sqltiming.logging.file"/>
<springProperty name="LOG4JDBC_SQLTIMING_LOG_LEVEL" source="log4jdbc.jdbc.sqltiming.level"/>
<logger name="jdbc.sqlonly" level="${LOG4JDBC_SQLTIMING_LOG_LEVEL}">
<appender class="ch.qos.logback.core.FileAppender">
<file>${LOG4JDBC_SQLTIMING_LOGGING_FILE_NAME}</file>
<encoder>
<pattern>${FILE_LOGGING_PATTERN}</pattern>
</encoder>
</appender>
</logger>
<!--
<logger name="jdbc.sqltiming" level="${LOG4JDBC_SQLTIMING_LOG_LEVEL}">
<appender class="ch.qos.logback.core.FileAppender">
<file>${LOG4JDBC_SQLTIMING_LOGGING_FILE_NAME}</file>
<encoder>
<pattern>${FILE_LOGGING_PATTERN}</pattern>
</encoder>
</appender>
</logger>
-->
The reason I'd commented out the last logger definition is because it did not work. So I tried to capture the 'sqlonly' logger output. When I run my application, it does generate an empty log file named "log4jdbc.log". However, the other log file capturing the generic application logs is getting generated just the same. Is there some minor mistake that is preventing this configuration setup from working as I expect it to?

Using Logback to catalina.out

I am using Logback in an application running in Tomcat. While my application works and, in the debugger, I see my logging statements reached, these statements never reach /opt/tomcat/logs/catalina.out. (By the way, I do see these statements in the IntelliJ IDEA debugger console, but upon deployment, they don't reach catalina.out.) Where do I begin?
In my WAR, WEB-INF/classes/logback.xml looks like this:
<configuration>
<appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${catalina.base}/logs/catalina.out</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<maxFileSize>10MB</maxFileSize>
<maxHistory>10</maxHistory>
</rollingPolicy>
<immediateFlush>true</immediateFlush>
<encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
<pattern>%date %level [%thread] %logger{40} %msg%n</pattern>
</encoder>
</appender>
<root level="INFO">
<appender-ref ref="FILE" />
</root>
</configuration>
In code, I do this for example:
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Validator
{
private static final Logger logger = LoggerFactory.getLogger( Validator.class );
...
public void foo()
{
logger.info( "Called foo()" );
Correspondingly, in pom.xml dependencies, I have this:
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>${logback-version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-access</artifactId>
<version>${logback-version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>${slf4j.version}</version>
</dependency>
I also tried this in logback.xml. It didn't create the file. All logfiles are owned by tomcat:tomcat. Tomcat owns the thread that writes to the log.
<file>${catalina.base}/logs/test.log</file>

The problem turned out to be the slf4j JARs and multiple bindings. See
https://www.slf4j.org/codes.html#multiple_bindings.
I eliminated slf4j-simple from my dependencies as shown above. The fact that two slf4j JARs were in conflict barred in essence logback.xml from having any effect upon logging behavior. Upon fixing this, JUnit tests still worked, the IDE-embedded Tomcat began to reveal TRACE-level statements when the level was set to TRACE, ditto when deployed to a real Tomcat installation where the statements come out (in catalina.out in my case).
One additional observation I can make is that if a log-level configuration change is made (say, by hand directly on logback.xml on the path /opt/tomcat/webapps/application/WEB-INF/classes/logback.xml), I found that Tomcat had to be bounced for it to take effect (even though I played with <configuration scan="true">, etc.).

Disable Azure service bus printing logs in cloud watch

I was getting following error message in aws lambda logs :
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
so i added maven depdenecies as :
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.21</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.21</version>
</dependency>
But on adding slfj4j dependencies unwated logs from azure service bus are also getting printed now eg.
[ReactorThread1288184d-400a-4928-b174-b819c8bd9ee1] INFO com.microsoft.azure.servicebus.primitives.MessagingFactory - starting reactor instance.
my log4j.xml looks like this :
<?xml version="1.0" encoding="UTF-8"?>
<Configuration packages="com.amazonaws.services.lambda.runtime.log4j2">
<Appenders>
<Lambda name="Lambda">
<PatternLayout>
<pattern>%d{yyyy-MM-dd HH:mm:ss} %X{AWSRequestId} %-5p %c{1}:%L - %m%n</pattern>
</PatternLayout>
</Lambda>
</Appenders>
<Loggers>
<Root level="info">
<AppenderRef ref="Lambda" />
</Root>
</Loggers>
</Configuration>
How can i disable these logs getting printed ?

I think the problem is related with the logging dependencies of your project.
On one hand, you have AWS Lambda over Log4j2, which uses Log4j2 for logging. On the other hand you have Azure Service Bus, which uses the SLF4J API facade for logging. You need to configure your system to support both logging approaches.
First of all, you need the following dependencies in your pom.xml file:
<dependencies>
...
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-log4j2</artifactId>
<version>1.2.0</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.13.2</version>
</dependency>
....
</dependencies>
The first dependency allows you to emit log traces to AWS Lambda.
The last one is the Log4j2 SLF4J java bridge, necessary for Azure Service Bus logging.
Please, also remove the dependency slf4j-simple associated with the group org.slf4j, it will be no necessary.
With this dependencies in place, please, include the following line:
<Logger name="com.microsoft.azure.servicebus" level="OFF"/>
In your XML configuration file (by convention, it is better to name your Log4j2 configuration file like log4j2.xml instead of log4j.xml, more appropriate for the old Log4j library version).
Your log4j2.xml should looks something like the following:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration packages="com.amazonaws.services.lambda.runtime.log4j2">
<Appenders>
<Lambda name="Lambda">
<PatternLayout>
<pattern>%d{yyyy-MM-dd HH:mm:ss} %X{AWSRequestId} %-5p %c{1}:%L - %m%n</pattern>
</PatternLayout>
</Lambda>
</Appenders>
<Loggers>
<Logger name="com.microsoft.azure.servicebus" level="OFF"/>
<Root level="info">
<AppenderRef ref="Lambda" />
</Root>
</Loggers>
</Configuration>

Firstly, this is not an error. The message means that there is no logger implementation present in the classpath and hence it is defaulting to NOP (No-operation) log. And as SLF4J is an abstraction of different logging frameworks, you also need to include specific logging framework in your classpath apart from only having SLF4J. Since you are trying to use Lambda appender, you need to add aws-lambda-java-log4j2 to your classpath. This will bring in required SLF4J dependencies also.
Latest version as of May 05, 2020:
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-log4j2</artifactId>
<version>1.2.0</version>
</dependency>

How to make java.util.logging send logs to Logback?

I'm working on an app that logs using the slf4j api:
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
...
private static final Logger LOG = LoggerFactory.getLogger(FreemarkerEmailPreviewGenerator.class);
...
LOG.error("Error generating email preview", e);
(Code above posted to show classes and packages in use, but pretty standard stuff.)
We use logback configured as follows:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>[%d{HH:mm:ss.SSS}] [%thread] [%-5level %logger{26} - %msg]%n
</pattern>
</encoder>
</appender>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
</root>
</configuration>
Some of our code makes use of 3rd party libraries that logs with java.util.logging - specifically freemarker. As you can see from the following console log entries, both logback and j.u.l are logging to the console, but they are not using the same config (the logback entries use our pattern, the j.u.l ones don't)
[12:24:38.842] [pool-2-thread-19] [INFO u.o.n.r.l.s.e.t.TemplateLoaderFromService - Finding template workflow/mail/templates/common/workflow-macros.ftl]
[12:24:38.859] [pool-2-thread-19] [INFO u.o.n.r.l.s.e.t.TemplateLoaderFromService - Loaded template workflow/mail/templates/common/workflow-macros.ftl as /workflow/mail/templates/common/workflow-macros.ftl from RegistryMailTemplateService.]
11-Jan-2017 12:24:38 freemarker.log.JDK14LoggerFactory$JDK14Logger error
SEVERE:
Expression domainContact is undefined on line 9, column 74 in workflow/mail/templates/common/workflow-macros.ftl.
The problematic instruction:
----------
==> ${domainContact.name} [on line 9, column 72 in workflow/mail/templates/common/workflow-macros.ftl]
Is it possible to make j.u.l logging use the logback config so that we have a single consistent logging config for the whole app?

Your application needs to have the following jars:
Application -> Freemarker -> java.util.logging -> SLF4J Api: jul-to-slf4j.jar
Application -> SLF4J API: slf4j-api.jar
SLF4J API -> logback: logback-classic.jar and logback-core.jar
Since your application already contains slf4j-api.jar and logback-classic.jar, you probably only have to add the jul-to-slf4j.jar
If you use maven:
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jul-to-slf4j</artifactId>
<version>1.7.22</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.8</version>
</dependency>
logback classic will transitively add logback-core and slf4j-api