操作方法：配置 Tomcat 9 通过 Log4j2 进行日志记录

Question

如何将 Tomcat 9 的内部日志记录（catalina 和 localhost）重定向到 Log4j2？

虽然有许多针对旧版本 Tomcat 和 Log4j 的指南，但我找不到有关 Tomcat 9 和 Log4j2 的任何“完整”内容；Apache Tomcat 9 文档指向“替代日志框架提供的说明”，Apache Log4j 文档指出（2. 中的 jar 名称已更正）：

Log4j 可以用作 Apache Tomcat 的日志框架。此支持是通过在启动类路径中包含 log4j-api、log4j-core 和 log4j-appserver jar 自动实现的。名为 log4j2-tomcat.xml、log4j2-tomcat.json、log4j2-tomcat.yaml、log4j2-tomcat.yml 或 log4j2-tomcat.properties 的文件还必须放置在引导类路径中。这最容易通过以下方式完成：

1. 在 catalina home 中创建一组名为 log4j2/lib 和 log4j2/conf 的目录。
2. 将 log4j-api-2.12.0.jar、log4j-core-2.12.0.jar 和 log4j-appserver-2.12.0.jar 放置在 log4j2/lib 目录中。
3. 在 log4j2/conf 目录中创建名为 log4j2-tomcat.xml、log4j2-tomcat.json、log4j2-tomcat.yaml、log4j2-tomcat.yml 或 log4j2-tomcat.properties 的文件。
4. 在tomcat bin目录下创建或修改setenv.sh以包含CLASSPATH=$CATALINA_HOME/log4j2/lib/*:$CATALINA_HOME/log4j2/conf

但是 log4j2-tomcat.* 配置文件中应该放入什么内容呢？

Answer 1

我在Apache Tomcat 7 文档中找到了一个示例属性文件，但由于该文件适用于 Log4j 1.x，因此我必须将其调整为 Log4j2 属性文件语法。这是结果：

# 'status' refers to log messages from Log4j2 itself
monitorInterval = 30
status = warn

property.loglevel.catalina = info
property.loglevel.localhost = info

property.layoutPattern.catalina = %d %-5p [%t] %-22.22c{1} %m%n
property.layoutPattern.localhost = %d %-5p [%t] %-30.30c{1} %m%n

# Roll-over the logs once per month using CronTriggerPolicy.

property.fileDatePattern.catalina = %d{yyyy-MM}
property.fileDatePattern.localhost = %d{yyyy-MM}

property.cronTriggerSchedule.catalina = 0 0 0 1 * ?
property.cronTriggerSchedule.localhost = 0 0 0 1 * ?

## Appenders

# N.B.: - No need to specify 'appenders = CATALINA, LOCALHOST, CONSOLE'
#         since these identifiers do not contain '.' characters.
#       - The sub-component identifiers 'policies' and 'cron' are arbitrarily
#         chosen; the actual type is specified via the 'type' attribute.
#       - 'DirectWriteRolloverStrategy' is used automatically since no 'fileName' specified.

appender.CATALINA.type = RollingFile
appender.CATALINA.name = RollingFile-CATALINA
appender.CATALINA.filePattern = ${sys:catalina.base}/logs/catalina.${fileDatePattern.catalina}.log
appender.CATALINA.layout.type = PatternLayout
appender.CATALINA.layout.pattern = ${layoutPattern.catalina}
appender.CATALINA.policies.type = Policies
appender.CATALINA.policies.cron.type = CronTriggeringPolicy
appender.CATALINA.policies.cron.schedule = ${cronTriggerSchedule.catalina}
appender.CATALINA.policies.cron.evaluateOnStartup = true
appender.CATALINA.filePermissions = rw-r-----
appender.CATALINA.fileOwner = tomcat
appender.CATALINA.fileGroup = adm

appender.LOCALHOST.type = RollingFile
appender.LOCALHOST.name = RollingFile-LOCALHOST
appender.LOCALHOST.filePattern = ${sys:catalina.base}/logs/localhost.${fileDatePattern.localhost}.log
appender.LOCALHOST.layout.type = PatternLayout
appender.LOCALHOST.layout.pattern = ${layoutPattern.localhost}
appender.LOCALHOST.policies.type = Policies
appender.LOCALHOST.policies.cron.type = CronTriggeringPolicy
appender.LOCALHOST.policies.cron.schedule = ${cronTriggerSchedule.localhost}
appender.LOCALHOST.policies.cron.evaluateOnStartup = true
appender.LOCALHOST.filePermissions = rw-r-----
appender.LOCALHOST.fileOwner = tomcat
appender.LOCALHOST.fileGroup = adm

# Uncomment if you want to keep logging to catalina.out after Log4j2 takes over.

#appender.CONSOLE.type = Console
#appender.CONSOLE.name = STDOUT
#appender.CONSOLE.layout.type = PatternLayout

## Configure which loggers log to which appenders

rootLogger.level = ${loglevel.catalina}
rootLogger.appenderRef.CATALINA.ref = RollingFile-CATALINA
#rootLogger.appenderRef.stdout.ref = STDOUT

# Here, the identifier does contain '.' characters, so we must specify the list.
loggers = org.apache.catalina.core.ContainerBase.[Catalina].[localhost]

logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].name = LOCALHOST
logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].level = ${loglevel.localhost}
logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].appenderRef.LOCALHOST.ref = RollingFile-LOCALHOST

我使用 Log4j2 的主要原因是能够获得每月的日志轮换，但是您可以轻松地按照自己的喜好调整所有内容，甚至无需重新启动 Tomcat。