How To Configure Log Using Log4j1.x

Contents 1 Introduction 2 Configuration 2.1 File 2.2 Log Verbosity 3 Rotation

Introduction

Logging allows developers to insert messages when code is executed, these messages can be used to understand different issues in the backend code, such as errors, performance problems, etc.

Openbravo uses log4j to log.

Configuration

Logging is configured by log4j.lcf file in Openbravo's config directory.

File

Typically log is redirected to a file. This file is determined by log4j.appender.*.File property. The defaults are:

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=${catalina.base}/logs/openbravo.log

log4j.appender.HB=org.apache.log4j.RollingFileAppender
log4j.appender.HB.File=${catalina.base}/logs/openbravo_hibernate.log

With this configuration, regular log will be placed in openbravo.log file in tomcat's log directory and log for hibernate will be in the same directory in openbravo_hibernate.log file.

Log Verbosity

Verbosity in the log is defined by the log levels:

ERROR WARN INFO DEBUG

Developer decides which is the level of each of the messages sent to the log.

It is possible to configure the log to display messages starting from any of these levels. Default configuration shows INFO and above. Log level can be configured globally and/or per class/package.

This can be modified in 2 ways:

• In log4j.lcf, it requires to deploy the changes (ant smartbuild) and restart Tomcat after modifying.
  • Globally: Change log4j.rootCategory=INFO to the desired level.
  • Per Java class or package: add lines like log4j.category.your.path.here=DEBUG where your.path is the fully qualified class name or pacakage.
• At runtime. The change doesn't require Tomcat to be restarted to be effective, but after restarting it configuration will be read from log4j.lcf and changes will be lost. To do it, log in the application as System Administrator, open Session Preferences window, click on Change Logs button, select the class you want to modify the log level for, select log level and click on Process button.

Rotation

In order to prevent log file to constantly increase, rotation is defined. Rotation sets up the policy to decide when log file will be archived and how many archives will be maintained.

It is configured with the following properties:

 log4j.appender.R.MaxFileSize=10000KB
 log4j.appender.R.MaxBackupIndex=10

In this example, log file will have at most 10MB. When this size is reached, current log is archived and a new log empty file is created, it will also keep up to 10 files, so when a new archive is created, the oldest existing one will be deleted.

Category: HowTo