Spring Boot makes it easy to configure logging for your application. By default, Spring Boot will configure the application to use the java.util.logging
(JUL) logging framework. This can be changed to use Log4j2, Logback, or slf4j by adding the appropriate starter dependency to the project.
In this article, we'll take a look at how to configure logging in Spring Boot. We'll start with a basic example and then move on to more advanced topics.
The simplest way to configure logging in Spring Boot is to add a logging.level
property to the application.properties
file. The logging level can be set for specific packages or for specific loggers. For example, the following configuration would set the logging level to DEBUG
for the com.example
package:
logging.level.com.example=DEBUG
If you want to set the logging level for all packages, you can use the root
logger. For example, the following configuration would set the logging level to INFO
for all packages:
logging.level.root=INFO
In addition to setting the logging level, you can also configure the format of the log output. By default, Spring Boot will output the log messages in the %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
format.
You can change the format by setting the logging.pattern.console
property. For example, the following configuration would output the log messages in the %d [%thread] %-5level %logger{36} - %msg%n
format:
logging.pattern.console=%d [%thread] %-5level %logger{36} - %msg%n
In addition to the console, Spring Boot can also log to a file. By default, the log messages will be output to a file spring.log
in the tmp
directory. You can change the location of the file by setting the logging.file
property. For example, the following configuration would output the log messages to a file /var/log/spring.log
:
logging.file=/var/log/spring.log
If you want to create a custom logger, you can use the logging.config
property to specify the location of the log4j2.xml file. For example, the following configuration would output the log messages to a file /var/log/spring.log
:
logging.config=log4j2.xml
In addition to the basic configuration, Spring Boot also provides a number of advanced features. For example, you can configure the loggers to output the log messages to multiple files. You can also set the log level for specific classes.
You can configure the loggers to output the log messages to multiple files by setting the logging.file.name
and logging.file.max-size
properties. For example, the following configuration would output the log messages to the files spring.log
and spring.log.1
in the tmp
directory:
logging.file.name=spring.log
logging.file.max-size=10MB
You can set the logging level for specific classes by setting the logging.level.{class}
property. For example, the following configuration would set the logging level to DEBUG
for the com.example.MyClass
class:
logging.level.com.example.MyClass=DEBUG
In this article, we've taken a look at how to configure logging in Spring Boot. We've seen how to set the logging level and how to change the format of the log output. We've also seen how to output the log messages to multiple files and how to set the logging level for specific classes.