Develop Reference

Google LoggingAppender and stdout

For debugging/testing purposes, I would like Google's Logback LoggingAppender to write to STDOUT instead to connect to Google's Logging API. According to https://github.com/googleapis/java-logging-logback, this should be possible by using redirectToStdout.
My logback.xml:
<appender name="CONSOLE" class="com.google.cloud.logging.logback.LoggingAppender">
<redirectToStdout>true</redirectToStdout>
</appender>
<root>
<level value="info" />
<appender-ref ref="CONSOLE" />
</root>
However, I get an error that no project was set. The error message:
14:48:36,515 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [com.google.cloud.logging.logback.LoggingAppender]
14:48:36,534 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [CONSOLE]
14:48:36,970 |-ERROR in ch.qos.logback.core.joran.spi.Interpreter#28:16 - RuntimeException in Action for tag [appender] java.lang.IllegalArgumentException: A project ID is required for this service but could not be determined from the builder or the environment. Please set a project ID using the builder.
at java.lang.IllegalArgumentException: A project ID is required for this service but could not be determined from the builder or the environment. Please set a project ID using the builder.
at at com.google.common.base.Preconditions.checkArgument(Preconditions.java:142)
...
Although that should not be necessary according to the documentation cited above, I also tried setting logDestinationProjectId. Note, that doesn't make sense in my case, as I want to run this configuration on my local machine for debug/test purposes. Also, that produced a different error (although that should be ignored according to the documentation).
Any hints what I am missing? Is my use case even supported? If not, how do you test a configuration change for your LoggingAppender before deploying it to Google Cloud?

The linked github issue was accepted and confirmed by a contributor. You can work around by setting an arbitrary project ID, i.e. by setting logDestinationProjectId:
<appender name="CONSOLE" class="com.google.cloud.logging.logback.LoggingAppender">
<redirectToStdout>true</redirectToStdout>
<logDestinationProjectId>TEST</logDestinationProjectId>
</appender>
<root>
<level value="info" />
<appender-ref ref="CONSOLE" />
</root>

How to disable console logging in spring-boot?

I'm using the default logging configuration of spring-boot.
How can I prevent the console output, while keeping the logging into a logfile configured with logging.file=myfile.log?
My goal is to not having console windows output, but only logging to that file.
Without having to create a specific logback.xml configuration. Because I'm using spring-boot for not having to configure the logging myself.

It turned out if I set the following property empty, the console logging is disabled:
logging.pattern.console=
Or commenting in xml if you use it
<!--<root level="error">-->
<!--<appender-ref ref="console"/>-->
<!--</root>-->

I created a file called logback.xml with the content:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/base.xml" />
<logger name="org.springframework" level="ERROR"/>
<logger name="org.hibernate" level="ERROR"/>
</configuration>
See this link for more information: https://www.mkyong.com/spring-boot/spring-boot-test-how-to-stop-debug-logs/

Create a file logback-spring.xml in /resources/ folder of your application.
Copy the below content in logback-spring.xml
<?xml version = "1.0" encoding = "UTF-8"?>
<configuration>
<appender name = "STDOUT" class = "ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%m%n</pattern>
</encoder>
</appender>
<root level = "INFO">
<appender-ref ref = "STDOUT"/>
</root>
</configuration>

All the supported logging systems can have the logger levels set in the Spring Environment using ‘logging.level.*=LEVEL’ where ‘LEVEL’ is one of TRACE, DEBUG, INFO, WARN, ERROR, FATAL, OFF. The root logger can be configured using logging.level.root. Example application.properties:
logging.level.root=WARN
logging.level.org.springframework.web=DEBUG
logging.level.org.hibernate=ERROR
Check this information: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html
You could also overwrite the logback configuration and provide the value OFF to it.
<configuration>
<!-- turn OFF all logging (children can override) -->
<root level="OFF">
<appender-ref ref="STDOUT" />
</root>
</configuration>
You can find more information at the following link: https://logback.qos.ch/manual/configuration.html#rootElement

Components written against log4j1 are not logging after log4j2 upgrade

I've been banging my head over this one for a few days and can't get it figured out. Log4j2 is backwards compatible if you add the log4j1 compatibility library.
My web-inf\lib has:
slf-api
log4j-1.2-api (backwards compat. library)
log4j-api (log4j2)
log4j-core (log4j2)
log4j-web (auto-wiring for web applications)
My web.xml has:
<!-- log4j2 auto-wiring -->
<context-param>
<param-name>log4jConfiguration</param-name>
<param-value>file:///${catalina.base}/conf/log4j2.xml</param-value>
</context-param>
My [tomcat]/conf/log4j2.xml is:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="debug">
<Appenders>
<!-- Appends to CONSOLE -->
<Console name="consoleAppender" target="SYSTEM_OUT">
<ThresholdFilter level="DEBUG" onMatch="ACCEPT" onMismatch="DENY" />
<PatternLayout pattern="%5p (%F:%L) - %m%n" />
</Console>
</Appenders>
<Loggers>
<Logger name="com.mycompany.componentA" level="WARN" />
<Logger name="com.mycompany.componentA.QueryLogger" level="DEBUG" />
<Logger name="com.mycompany.mycode" level="DEBUG" />
<Root level="WARN">
<AppenderRef ref="consoleAppender" />
</Root>
</Loggers>
</Configuration>
I have upgraded code under my control (com.mycompany.mycode) to log4j2 APIs and they work/log flawlessly. Code that is not under my control but was written against log4j1 (com.mycompany.componentA) just simply fails to log at all. No errors, no debugs, nothing.
Something interesting though... when I start the application I get a log4j1 warning about incorrect configurations when the application starts. This also stumps me because there are no log4j1 libraries (except the compatibility API) in the WAR. Warning is:
log4j:WARN No appenders could be found for logger (com.mycompany.componentB)
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

EDIT: I (finally) figured out what's going on. One of my dependencies did a horribly bad thing and BUNDLED the log4j1 classes into it's final jar. So there are no log4j1 jars on the classpath, but there are log4j1 CLASSES on the classpath.
The only way I was able to get this working was to:
Create BOTH a log4j1 and log4j2 XML configuration files (even though the log4j2 configuration contained all the loggers I wanted)
Let Log4j2 auto-wire itself via the 'log4j-web' artifact + 'log4jConfiguration' web.xml parameter
Manually wire log4j1 by calling the deprecated Log4jConfigurer.initLogging(...) API on server startup
This is probably horribly incorrect, but as indicated above, it was the only way I got it working after weeks of fooling around.
My understanding of the lo4j1 bridge is that wiring up log4j2 and including the bridge is all that should be required (e.g. no need to manually wire log4j1). In practice, that does not seem to be occurring.

That error message means you still have the log4j-1.x jar in your application. Look for it in your WEB-INF/lib and remove it and then it should work.

If not in WEB-INF/lib, then perhaps in your web container (Tomcat?) shared lib folder? Ralph is right that this error message is generated by Log4j-1.2, so it is on the classpath somewhere... Try printing the value of System property java.class.path if necessary.
Update: another way to find the location of the Log4j1 jar is by printing the value of org.apache.log4j.AppenderSkeleton.class.getResource("/org/apache/log4j/AppenderSkeleton.class") from your application.
(I originally suggested Category but this also exists in the Log4j 1 bridge, so AppenderSkeleton is better.)

Connection to database in a managed thread, Debug values doesn't appear in Tomcat console or logs

I am facing this trouble for a long time now without accessing the debug logs of the managed Threads in my Spring boot application when run on Tomcat. All the logs appear when run on the Eclipse/STS.
In Tomcat logs, I can only see the main Tread Logs.
I am connection to a database through JDBC and this is happening in a separate thread. I tried to follow the log configuration documentation but none of them helps to get the debug logs of these threads. So I do not actually see the exact problem of what is causing the connection to fail.
Here is what I tried so far:
I tried with the following logback.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<!-- <appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
<Target>System.out</Target> <encoder> <pattern>%d{yyyy-MM-dd HH:mm:ss} %-5p
%c{1}:%L - %m%n</pattern> </encoder> </appender> <logger name="com.biscoind"
additivity="false" level="TRACE"> <appender-ref ref="stdout" /> </logger>
<root level="debug"> <appender-ref ref="stdout" /> </root> -->
<include resource="org/springframework/boot/logging/logback/base.xml" />
<logger name="org.springframework.web" level="DEBUG" />
</configuration>
When that did not resolve the issue I removed this file and see if by default, if it logs all the treads. But it did not.
So, I added the following configurations to the application.properties
logging.level.org.springframework.web:TRACE
logging.level.org.hibernate:ERROR
Then It seemed to me that this is only logging out the above namespaces, I again added
debug=true
logging.level.org.springframework.web:DEBUG
logging.level.org.hibernate:DEBUG
Tried and it did not work.
I added my namespaces also and tried as follwing,
debug=true
logging.level.com.mydomain:DEBUG
logging.level.org.springframework.web:DEBUG
logging.level.org.hibernate:DEBUG
That did not work also, I am now confused on the what should I do with the config relative to logging to make the logs to appear for the tread executions.
Irrespective of the treads, because of the property spring.jpa.show-sql=true it logs the queries that are made.

It was not a problem with the threads at all. The application was working correctly in the development environment. The problem was in the deployment environment.
It turned out to be a Java version miss-match with the jar files and the JVM version. The jars were build using Java 8 and it was running on Java 7 JVM.
When the JMV was changed to Java-8. It worked fine. So Next time I will be more careful with the version mismatch.

Excluding only one level of Log4j Logger

I'm using Log4j in a application in which I also use Axis2 and Jetty web server.
I configured the Log4J property file to exclude these classes from logging when in debug priority. But when I did this, the other priority messages also began to be excluded from the main logger.
Is there a way that I can tell Log4j that I just want to log INFO logs from these classes while logging debug logs from my classes?
Here's what I have done:
#Jetty Server and Axis2
log4j.category.org.apache.axiom=DEBUG
log4j.additivity.org.apache.axiom=false
log4j.category.org.apache.axis2=DEBUG
log4j.additivity.org.apache.axis2=false
################# MAIN LOGGER #################
log4j.rootCategory=DEBUG, mainLogger
#File configuration
But as I said this configuration also exclude INFO messages from the main logger.

No, set the Root level to DEBUG, and
log4j.category.org.apache.axiom=INFO
log4j.category.org.apache.axis2=INFO
Also, do not set the additivity to false.
When you're starting from scratch, you might want to use the more modern XML config format right away. There, it would look like this:
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="FILE" class="org.apache.log4j.RollingFileAppender">
...
</appender>
<category name="com.apache.axiom">
<priority value="INFO" />
</category>
<root>
<priority value ="DEBUG" />
<appender-ref ref="FILE" />
</root>
</log4j:configuration>

Set the rootCategory to INFO, set an apropriate Logger of your classes (e.g. org.myemployer.myapp) to DEBUG

Using this you can set your log level:
import org.apache.log4j.Level;
public static Logger logger = null;
logger.setLevel(Level.DEBUG);
and
Logger.getRootLogger().setLevel(Level.INFO);