Learn spring boot logging configuration via application.properties
file in simple and easy to follow instructions. In the default structure of a Spring Boot web application, we can locate the application.properties
file under the resources
folder.
logging.level.org.springframework=DEBUG logging.level.com.howtodoinjava=DEBUG #output to a temp_folder/file logging.file=${java.io.tmpdir}/application.log # Logging pattern for the console logging.pattern.console= %d{yyyy-MM-dd HH:mm:ss} - %msg%n # Logging pattern for file logging.pattern.file= %d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%
Table of Contents 1. Spring boot default logging 2. Spring boot logging levels 3. Spring boot logging patterns 4. Log output to file 5. Active profiles to load environment specific logging configuration 6. Color-coded log output
1. Spring boot default logging
To understand default spring boot logging, lets put logs in spring boot hello world example. Just to mention, there is no logging related configuration in application.properties
file. If we see any configuration in downloaded application, please remove it.
private final Logger LOGGER = LoggerFactory.getLogger(this.getClass()); @RequestMapping("/") public String home(Map<String, Object> model) { LOGGER.debug("This is a debug message"); LOGGER.info("This is an info message"); LOGGER.warn("This is a warn message"); LOGGER.error("This is an error message"); model.put("message", "HowToDoInJava Reader !!"); return "index"; }
Start the application. Access application at browser and verify log messages in console.
2017-03-02 23:33:51.318 INFO 3060 --- [nio-8080-exec-1] c.h.app.controller.IndexController : info log statement printed 2017-03-02 23:33:51.319 WARN 3060 --- [nio-8080-exec-1] c.h.app.controller.IndexController : warn log statement printed 2017-03-02 23:33:51.319 ERROR 3060 --- [nio-8080-exec-1] c.h.app.controller.IndexController : error log statement printed
Note down the observation that Default logging level is INFO – because debug log message is not present.
There is fixed default log message pattern which is configured in different base configuration files.
%clr{%d{yyyy-MM-dd HH:mm:ss.SSS}}{faint} %clr{${LOG_LEVEL_PATTERN}} %clr{${sys:PID}}{magenta} %clr{---}{faint} %clr{[%15.15t]}{faint} %clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}
The above pattern print these listed log message parts with respective color coding applied:
- Date and Time — Millisecond precision.
- Log Level — ERROR, WARN, INFO, DEBUG or TRACE.
- Process ID.
- A — separator to distinguish the start of actual log messages.
- Thread name — Enclosed in square brackets (may be truncated for console output).
- Logger name — This is usually the source class name (often abbreviated).
- The log message
2. Spring boot logging levels
When a message is logged via a Logger it is logged with a certain log level. In the application.properties
file, you can define log levels of Spring Boot loggers, application loggers, Hibernate loggers, Thymeleaf loggers, and more. To set the logging level for any logger, add properties starting with logging.level
.
Logging level can be one of one of TRACE
, DEBUG
, INFO
, WARN
, ERROR
, FATAL
, OFF
. The root logger can be configured using logging.level.root
.
#logging.level.root=WARN logging.level.org.springframework.web=ERROR logging.level.com.howtodoinjava=DEBUG
In above configuration, I upgraded log level for application classes to DEBUG (from default INFO). Now observe the logs:
2017-03-02 23:57:14.966 DEBUG 4092 --- [nio-8080-exec-1] c.h.app.controller.IndexController : debug log statement printed 2017-03-02 23:57:14.967 INFO 4092 --- [nio-8080-exec-1] c.h.app.controller.IndexController : info log statement printed 2017-03-02 23:57:14.967 WARN 4092 --- [nio-8080-exec-1] c.h.app.controller.IndexController : warn log statement printed 2017-03-02 23:57:14.967 ERROR 4092 --- [nio-8080-exec-1] c.h.app.controller.IndexController : error log statement printed
3. Spring boot logging patterns
To change the logging patterns, use logging.pattern.console
and logging.pattern.file
properties.
# Logging pattern for the console logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss} - %msg%n # Logging pattern for file logging.pattern.file=%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n
After changing console logging pattern in application, log statements are printed as below:
2017-03-03 12:59:13 - This is a debug message 2017-03-03 12:59:13 - This is an info message 2017-03-03 12:59:13 - This is a warn message 2017-03-03 12:59:13 - This is an error message
4. Log output to file
To print the logs in file, use logging.file
or logging.path
property.
logging.file=c:/users/howtodoinjava/application-debug.log
Verify the logs in file.
2017-03-03 13:02:50.608 DEBUG 10424 --- [http-nio-8080-exec-1] c.h.app.controller.IndexController : This is a debug message 2017-03-03 13:02:50.608 INFO 10424 --- [http-nio-8080-exec-1] c.h.app.controller.IndexController : This is an info message 2017-03-03 13:02:50.608 WARN 10424 --- [http-nio-8080-exec-1] c.h.app.controller.IndexController : This is a warn message 2017-03-03 13:02:50.609 ERROR 10424 --- [http-nio-8080-exec-1] c.h.app.controller.IndexController : This is an error message
5. Active profiles to load environment specific logging configuration
It is desirable to have multiple configurations for any application – where each configuration is specific to a particular runtime environment. In spring boot, you can achieve this by creating multiple application-{profile}.properties
files in same location as application.properties
file.
Profile specific properties always override the non-profile specific ones. If several profiles are specified, a last wins strategy applies.
If I have two environments for my application i.e. prod
and dev
. Then I will create two profile specific properties files.
5.1. application-dev.properties
logging.level.com.howtodoinjava=DEBUG logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss} - %msg%n
5.2. application-prod.properties
logging.level.com.howtodoinjava=ERROR logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss} - %msg%n
To supply profile information to application, property spring.profiles.active
is passed to runtime.
$ java -jar -Dspring.profiles.active=prod spring-boot-demo.jar
6. Color-coded log output
If your terminal supports ANSI, color output will be used to aid readability. You can set spring.output.ansi.enabled
value to either ALWAYS
, NEVER
or DETECT
.
Color coding is configured using the %clr
conversion word. In its simplest form the converter will color the output according to the log level.
FATAL and ERROR – Red
WARN – Yellow
INFO, DEBUG and TRACE – Green
Drop me your questions in comments section.
Happy Learning !!
References:
Spring Boot – How to logging
Spring boot features – Logging
Leandro
Thanks for this tutorial.
Main help here is that when we use @Slf4j we can setup a property like below example:
logging.level.PACKAGE_ROOT = debug
Aastha jain
Hii,
I want to append messageId to each line of log file which will be fetched from request body of microservice.How can we do that?
prakash kumar behera
Hi,
I am doing a spring boot based maven project. There I implemented log4j and I am using Console Appender. I am configuring all logging code in the application.properties file. My requirement is I want to give the Buffersize and BufferIo, How to write this code please tell me. Already I wrote these things-
#Log4j Level Order/Priority=> Trace < Debug < Info < Warn < Error < Fatal
Thanks & Regards,
Prakash Kumar Behera
Khushboo
How can we add an ASYNC appender in application.properties file
Balaji
I am unable to log onto file.
Prashanth
Hi,
I don’t want console logs.
So I have added
LOG_FOLDER=** in application.conf
logging.pattern.console=OFF in application.properties
It is working. I mean no two logs(console,file). But does logging.pattern.console take the value OFF?
someon
is it really possible to call getClass() in this ?
shameer
Hello Lokesh Gupta,
Could you please help me to figure out how to configure “RollingFileAppender” in application.properties file
Thanks,
SHameer
Lokesh Gupta
Spring boot aims to provide logging support with minimum configuration, so it provides that by making many things defaults and limited. It uses internally base.xml file. This
base.xml
file includes file-appender.xml. It has below configuration –You inject above properties using
application.properties
file-That’s all is possible with default logging configuration within
application.properties
. If you want to customize more, the you need to override the logging config in separatelogback.xml
file. To do so, configure config location inapplication.properties
file and then customize config.e.g.