[logging] Spring Boot: How can I set the logging level with application.properties?

This is very simple question, but I cannot find information.
(Maybe my knowledge about Java frameworks is severely lacking)

How can I set the logging level with application.properties?
And logging file location, etc?

in spring boot project we can write logging.level.root=WARN but here problem is, we have to restart again even we added devtools dependency, in property file if we are modified any value will not autodetectable, for this limitation i came to know the solution i,e we can add actuator in pom.xml and pass the logger level as below shown in postman client in url bar http://localhost:8080/loggers/ROOT or http://localhost:8080/loggers/com.mycompany and in the body you can pass the json format like below

{
  "configuredLevel": "WARN"
}

If you are on Spring Boot then you can directly add following properties in application.properties file to set logging level, customize logging pattern and to store logs in the external file.

These are different logging levels and its order from minimum << maximum.

OFF << FATAL << ERROR << WARN << INFO << DEBUG << TRACE << ALL

# To set logs level as per your need.
logging.level.org.springframework = debug
logging.level.tech.hardik = trace

# To store logs to external file
# Here use strictly forward "/" slash for both Windows, Linux or any other os, otherwise, its won't work.      
logging.file=D:/spring_app_log_file.log

# To customize logging pattern.
logging.pattern.file= "%d{yyyy-MM-dd HH:mm:ss} - %msg%n"

Please pass through this link to customize your log more vividly.

https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html

In my current config I have it defined in application.yaml like that:

logging:
  level:
    ROOT: TRACE

I am using spring-boot:2.2.0.RELEASE. You can define any package which should have the TRACE level like that.

In case you want to use a different logging framework, log4j for example, I found the easiest approach is to disable spring boots own logging and implement your own. That way I can configure every loglevel within one file, log4j.xml (in my case) that is.

To achieve this you simply have to add those lines to your pom.xml:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j</artifactId>
</dependency>

You probably already have the first dependency and only need the other two. Please note, that this example only covers log4j.
That's all, now you're all set to configure logging for boot within your log4j config file!

With Springboot 2 you can set the root logging Level with an Environment Variable like this:

logging.level.root=DEBUG

Or you can set specific logging for packages like this:

logging.level.my.package.name=TRACE

You can try setting the log level to DEBUG it will show everything while starting the application

logging.level.root=DEBUG

Making sure Dave Syer tip gets some love, because adding debug=true to application.properties will indeed enable debug logging.

In case of eclipse IDE and your project is maven, remember to clean and build the project to reflect the changes.

If you want to set more detail, please add a log config file name "logback.xml" or "logback-spring.xml".

in your application.properties file, input like this:

logging.config: classpath:logback-spring.xml

in the loback-spring.xml, input like this:

    <?xml version="1.0" encoding="UTF-8"?>
    <configuration>
        <include resource="org/springframework/boot/logging/logback/base.xml"/>

        <appender name="ROOT_APPENDER" class="ch.qos.logback.core.rolling.RollingFileAppender">

            <filter class="ch.qos.logback.classic.filter.LevelFilter">
                <level>INFO</level>
                <onMatch>ACCEPT</onMatch>
                <onMismatch>DENY</onMismatch>
            </filter>

            <file>sys.log</file>

            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">


                <fileNamePattern>${LOG_DIR}/${SYSTEM_NAME}/system.%d{yyyy-MM-dd}.%i.log</fileNamePattern>

                <timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                    <maxFileSize>500MB</maxFileSize>
                </timeBasedFileNamingAndTriggeringPolicy>
            </rollingPolicy>

            <encoder>
                <pattern>%-20(%d{yyy-MM-dd HH:mm:ss.SSS} [%X{requestId}]) %-5level - %logger{80} - %msg%n
                </pattern>
            </encoder>
        </appender>


        <appender name="BUSINESS_APPENDER" class="ch.qos.logback.core.rolling.RollingFileAppender">
            <filter class="ch.qos.logback.classic.filter.LevelFilter">
                <level>TRACE</level>
                <onMatch>ACCEPT</onMatch>
                <onMismatch>DENY</onMismatch>
            </filter>

            <file>business.log</file>

            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">

                <fileNamePattern>${LOG_DIR}/${SYSTEM_NAME}/business.%d{yyyy-MM-dd}.%i.log</fileNamePattern>

                <timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                    <maxFileSize>500MB</maxFileSize>
                </timeBasedFileNamingAndTriggeringPolicy>
            </rollingPolicy>

            <encoder>
                <pattern>%-20(%d{yyy-MM-dd HH:mm:ss.SSS} [%X{requestId}]) %-5level - %logger{80} - %msg%n
                </pattern>
            </encoder>
        </appender>


        <logger name="{project-package-name}" level="TRACE">
            <appender-ref ref="BUSINESS_APPENDER" />
        </logger>

        <root level="INFO">
            <appender-ref ref="ROOT_APPENDER" />
        </root>

    </configuration>

The proper way to set the root logging level is using the property logging.level.root. See documentation, which has been updated since this question was originally asked.

Example:

logging.level.root=WARN

For the records: the official documentation, as for Spring Boot v1.2.0.RELEASE and Spring v4.1.3.RELEASE:

If the only change you need to make to logging is to set the levels of various loggers then you can do that in application.properties using the "logging.level" prefix, e.g.

logging.level.org.springframework.web: DEBUG logging.level.org.hibernate: ERROR

You can also set the location of a file to log to (in addition to the console) using "logging.file".

To configure the more fine-grained settings of a logging system you need to use the native configuration format supported by the LoggingSystem in question. By default Spring Boot picks up the native configuration from its default location for the system (e.g. classpath:logback.xml for Logback), but you can set the location of the config file using the "logging.config" property.

Suppose your application has package name as com.company.myproject. Then you can set the logging level for classes inside your project as given below in application.properties files

logging.level.com.company.myproject = DEBUG

logging.level.org.springframework.web = DEBUG and logging.level.org.hibernate = DEBUG will set logging level for classes of Spring framework web and Hibernate only.

For setting the logging file location use

logging.file = /home/ubuntu/myproject.log

Existing answers are greats. I just want to share with you a new spring boot feature allowing to group logs and set logging level on the whole group.

Exemple from the docs :

• Create a logging group

logging.group.tomcat=org.apache.catalina, org.apache.coyote, org.apache.tomcat

• Set the logging level for group

logging.level.tomcat=TRACE

It's nice feature which brings more flexibility.

You can do that using your application.properties.

logging.level.=ERROR -> Sets the root logging level to error
...
logging.level.=DEBUG -> Sets the root logging level to DEBUG

logging.file=${java.io.tmpdir}/myapp.log -> Sets the absolute log file path to TMPDIR/myapp.log

A sane default set of application.properties regarding logging using profiles would be: application.properties:

spring.application.name=<your app name here>
logging.level.=ERROR
logging.file=${java.io.tmpdir}/${spring.application.name}.log

application-dev.properties:

logging.level.=DEBUG
logging.file=

When you develop inside your favourite IDE you just add a -Dspring.profiles.active=dev as VM argument to the run/debug configuration of your app.

This will give you error only logging in production and debug logging during development WITHOUT writing the output to a log file. This will improve the performance during development ( and save SSD drives some hours of operation ;) ).