I have a Spring Boot project with a dependency to a third party library. This library uses SLF4J with Log4j2 for logging, and has a log4j2.xml with a pattern layout defined.
The problem is that the pattern layout of this dependency is used as the pattern for my application, ignoring the layout defined in application.properties.
If I can't modify the source code of this third party lib, is possible to configure my app in order to ignore the log4j2.xml?
One solution that you can try is to define your own log4j2 configuration file and give its path in log4j.configurationFile system property. When you define your own log4j2 configuration file, you can control how much logging you want and in which pattern.
The reason behind this is - When Log4j starts it tries to locate all the ConfigurationFactory plugins and arrange them in weighted order from highest to lowest. And as per log4j2 Automation Configuration, setting system property log4j.configurationFile has highest weight.
If log4j will found configuration file using this system property, then it will not scan classpath for locating log4j2.xml file which is present in your dependent library.
Related
I have update our code from log4j to log4j 2.17.1 And I want to stored the log file to servers under the Apache tomcat. I am using the log4j2.properties mentioned below.
When I run the code, then the logs file is printed in under code structure(see in below attached screenshot)but I want to print the logs file in QA-Servers under apache tomcat.
Please help me to solve the issue.
TL;DR: use ${sys:catalina.base}.
The property substitution in Log4j 2.x differs from Log4j 1.x (cf. documentation). The most prominent change is that:
in Log4j 1.x ${catalina.base} is looked up in Java system properties and, if the system property does not exist, in the configuration file,
in Log4j 2.x ${catalina.base} is looked up only in the configuration file.
In both cases if the property can not be resolved the placeholder is left unchanged.
In Log4j 2.x all external property lookups must be prefixed using an appropriate prefix. The exact equivalent of Log4j 1.x behavior is ${sys:catalina.base}. Therefore you can use:
# Fallback
property.catalina.base=.
appender.rolling.fileName=${sys:catalina.base}/logs/aseq_wiptmobile_qa-1.applog
I read the configuration manual page https://logging.apache.org/log4j/2.x/manual/configuration.html
and it just says
Log4j has the ability to automatically configure itself during initialization. When Log4j starts it will locate all the ConfigurationFactory plugins and arrange them in weighted order from highest to lowest.
It just says When Log4j starts but it doesn't mean anything precise.
So the question is: when does log4j2 read the configuration file?
in case of web-applications (servlet 3.0 and above), log4j2 starts with your web-application. therefore you should include the log4j-web.jar this jar is a web-fragment, wich is configured to be loaded before any other web-fragments in the project. at this point log4j2 searches for a configuration-file to load
please refer to https://logging.apache.org/log4j/2.x/manual/webapp.html and take a look at the screenshot
I am having project A and project B, A has jar dependency of project B. I have defined log4j.xml in project A but I am not able to see logs of sub-project(B.jar) in file appender as well as tomcat server console. Does project B will take log4j.xml form parent project A or not then which config does it use?
There is one log4j config for your entire JVM (unless you're working in a containerized environment using class loaders and.... that's not what's described).
Missing log messages implies that the configuration from log4j either (a) isn't what you think it is (i.e. a different log4j.xml is being used) or (b) doesn't have the right settings for the missing log lines.
Adding the following to the JVM at startup may help:
-Dlog4j.debug
It may also be possible to browse the log4j settings via MBeans in jconsole.
If you want all apps (WAR files) in a Tomcat instance to have the same logging configs, the simple solution is to arrange that all WAR files have a copy of the same config file.
If you want the apps to share a common logging framework (with a single configuration), then you should consider using Context Selectors, as described in the Log4j 2 documentation.
Using Context Selectors
There are a few patterns for achieving the desired state of logging separation using ContextSelectors:
Place the logging jars in the container's classpath and set the system property log4j2.contextSelector to org.apache.logging.log4j.core.selector.BasicContextSelector. This will create a single LoggerContext using a single configuration that will be shared across all applications.
Place the logging jars in the container's classpath and use the default ClassLoaderContextSelector. Follow the instructions to initialize Log4j 2 in a web application. Each application can be configured to share the same configuration used at the container or can be individually configured. If status logging is set to debug in the configuration there will be output from when logging is initialized in the container and then again in each web application.
Follow the instructions to initialize Log4j 2 in a web application and set the system property or servlet context parameter log4j2.contextSelector to org.apache.logging.log4j.core.selector.JndiContextSelector. This will cause the container to use JNDI to locate each web application's LoggerContext. Be sure to set the isLog4jContextSelectorNamed context parameter to true and also set the log4jContextName and log4jConfiguration context parameters.
The exact method for setting system properties depends on the container. For Tomcat, edit $CATALINA_HOME/conf/catalina.properties. Consult the documentation for other web containers.
I don't think there is a direct equivalent in Log4j 1.x.
I am writing Java code that tests a Java library. The library includes its own Log4j2 configuration as part of the distribution.
I would like to use Log4j2 in my test code without modifying the library's configuration.
Is there a way to have a separate Log4j2 configuration for my test code?
This is all running as command-line Java, no servers or web involvement at all.
EDIT
What I want is to be able to configure loggers, appenders, etc for the test code to use, and at the same time have the library code use its own separate configuration file for its logging.
The idea is to use Log4j2 in my test code, but without having to change the library's configuration file. Since the library configuration file is part of the library's distribution, I don't want to change it for testing.
This may be helpful:
Log4j2 will first look for log4j2-test.xml in the classpath
if that file is not found, it will look for log4j2.xml in the classpath
So one option is to copy the library's configuration (log4j2.xml) to log4j2-test.xml and add your own configuration to log4j2-test.xml.
Furthermore, Log4j2 supports XInclude in XML configuration, so you could use that feature to avoid duplicating the library's configuration in your log4j2-test.xml.
Log4j2 supports "Composite Configuration" which exactly matches your requirement. All you need to do is provide path to multiple files in log4j.configurationFile property. This can be passed from command line or added to log4j2.component.properties file in your application.
References
https://logging.apache.org/log4j/2.x/manual/configuration.html#CompositeConfiguration
https://logging.apache.org/log4j/2.x/manual/configuration.html#SystemProperties
There are two step you can try to solve for your issue
Create your own configuration file with your custom name(eg: xyz.properties/.xml)
You must add the following line to your java runtime command
cmd> java -Dlog4j.configuration=location/xyz.properties
If you use diffent name for configuration rather log4j.properties/.xml file you need to configure that file at runtime by above command for more info have a look here..
Correct format for using an alternate XML file to log4j2.xml:
java -Dlog4j.configurationFile=./location/log4j2-custom.xml
Assuming ./location/log4j2-custom.xml exists and is the new XML to replace log4j2.xml in this run
See:
https://github.com/kamalcph/Log4j2Examples/blob/master/src/main/java/in/co/nmsworks/log4j2/examples/CompositeConfigurationExample.java
Referencing https://logging.apache.org/log4j/2.x/manual/configuration.html states that you can add multiple comma separated files under log4j2.configurationFile property.
To use multiple configuration files, depending on the environment you must set the.
for example:
if (env.equals("DEV")) {
setConfigFile("log4j2-dev.xml");
}
public static void setConfigFile(String logConfigFile) {
File file = new File(logConfigFile);
LoggerContext context = (org.apache.logging.log4j.core.LoggerContext) LogManager.getContext(false);
context.setConfigLocation(file.toURI());
}
first configure application.yaml file
spring:
profiles:
active: dev
---
spring:
message: running in the dev profile //just to output the message in the log
profiles: dev
logging.config: classpath:log4j2-dev.xml
---
spring:
profiles: prod
logging.config: classpath:log4j2-prod.xml
and create these similar files in your classpath
* log4j2-dev.xml
* log4j2-prod.xml
Does Spring provide any way to output the actual content of the classpath environment variable when it is loading a resource in a context configuration file?
<!-- Import the special context -->
<import resource="classpath:mySpecialApplicationContext.xml"/>
I set the Log4J logging level to ALL for Springframework classes but this value does not appear to be logged by the framework. I am trying to figure out if Spring is loading this from a dependency, and I want to see the classpath setting during application runtime. The application is built by Maven with many dependencies.
If there are two or more mySpecialApplicationContext.xml's in the classpath, which one does Spring use?
Thank you.
You can see the relevant (I think) source code at http://goo.gl/9dK2c
In short:
No, the classpath is not logged
The details of what would be loaded when there is more than one matching resource in the classpath are ClassLoader dependent - the DefaultResourceLoader uses the thread's classloader, but typically, the first one found would be used.