从logback配置文件中读取环境变量

Question

我有这个logback.xml文件:

<configuration debug="true" scan="true" scanPeriod="60 seconds">

  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <layout class="ch.qos.logback.classic.PatternLayout">
      <Pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</Pattern>
    </layout>
  </appender>

  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <File>${MY_HOME}/logs/mylog.log</File>

    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <FileNamePattern>logs/my.%d{yyyy-MM-dd}.log</FileNamePattern>
      <MaxHistory>30</MaxHistory>
    </rollingPolicy>

    <layout class="ch.qos.logback.classic.PatternLayout">
      <Pattern>%d{HH:mm:ss.SSS} [%thread] %-5level - %msg%n</Pattern>
    </layout>

  </appender> 

  <root level="TRACE">
    <appender-ref ref="FILE"/>
  </root>

</configuration>

并且${MY_HOME}是一个已定义的系统变量(echo $MY_HOME在linux上显示正确的路径).

问题是,logback似乎没有正确读取它,它存储日志 MY_HOME_IS_UNDEFINED/logs/my.log

我究竟做错了什么？非常感谢!

编辑:我犯了一个错误,把OSC_HOME放在我真正意味着MY_HOME的地方.对于那个很抱歉

Answer 1

与其他人所说的相反,logback文档明确指出 "在替换期间,首先在本地作用域中查找属性,在​​第二个上下文作用域中查找属性,在​​第三个系统属性作用域中查找属性,在第四个和最后一个OS环境中查找属性" .因此,如果在环境中定义属性,则logback将找到它.

在Eclipse中运行我的项目时遇到了同样的问题.如果这是您遇到的问题,可以通过运行配置 - >环境并添加MY_HOME到环境变量来修复.

不确定为什么默认情况下它没有加载本机环境.甚至还有一个名为"将环境附加到原生环境"的选项,这似乎对我没有任何影响.

Answer 2

还有一种从配置文件中读取环境变量的替代方法.您可以使用上下文侦听器将自定义变量放入logback上下文.

logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration debug="true" scan="true" scanPeriod="30 seconds">

    <!-- THIS IS OUR CUSTOM CONTEXT LISTENER -->
    <contextListener class="com.myapp.logging.listener.LoggerStartupListener"/>

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>[%-5level] %d{HH:mm:ss.SSS} [%.6thread] %logger - %msg%n</pattern>
            <charset>UTF-8</charset>
        </encoder>
    </appender>

    <appender name="FILEOUT" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${MY_HOME}/${LOG_FILE}.log</file>
        <append>true</append>
        <!-- Support multiple-JVM writing to the same log file -->
        <prudent>true</prudent>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- Daily rollover -->
            <fileNamePattern>${MY_HOME}/${LOG_FILE}.%d{yyyy-MM-dd}.log</fileNamePattern>
            <!-- Keep 7 days' worth of history -->
            <maxHistory>7</maxHistory>
        </rollingPolicy>
        <encoder>
            <pattern>[%-5level] %d{HH:mm:ss.SSS} [%.6thread] %logger - %msg%n</pattern>
            <charset>UTF-8</charset>
        </encoder>
    </appender>

    <root level="INFO">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="FILEOUT"/>
    </root>
</configuration>

LoggerStartupListener.java

package com.myapp.logging.listener;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.spi.LoggerContextListener;
import ch.qos.logback.core.Context;
import ch.qos.logback.core.spi.ContextAwareBase;
import ch.qos.logback.core.spi.LifeCycle;

public class LoggerStartupListener extends ContextAwareBase implements LoggerContextListener, LifeCycle {

    private static final String DEFAULT_LOG_FILE = "MYAPP";

    private boolean started = false;

    @Override
    public void start() {
        if (started) return;

        String userHome = System.getProperty("user.home"); 

        String logFile = System.getProperty("log.file"); // log.file is our custom jvm parameter to change log file name dynamicly if needed

        logFile = (logFile != null && logFile.length() > 0) ? logFile : DEFAULT_LOG_FILE;

        Context context = getContext();

        context.putProperty("MY_HOME", userHome);
        context.putProperty("LOG_FILE", logFile);

        started = true;
    }

    @Override
    public void stop() {
    }

    @Override
    public boolean isStarted() {
        return started;
    }

    @Override
    public boolean isResetResistant() {
        return true;
    }

    @Override
    public void onStart(LoggerContext context) {
    }

    @Override
    public void onReset(LoggerContext context) {
    }

    @Override
    public void onStop(LoggerContext context) {
    }

    @Override
    public void onLevelChange(Logger logger, Level level) {
    }
}

Answer 3

你或许是的意思MY_HOME.在您的配置文件中有参考OSC_HOME.有关详细信息,请参阅Logback的变量替换规则.

您可以将环境变量作为Java System属性传递,然后Logback将执行变量替换.您可以在命令行中将其作为JVM选项传递.例如:

java -DMY_HOME=${MY_HOME} -cp ... MainClass

或者您可以在配置文件中定义MY_HOME.

<configuration debug="true" scan="true" scanPeriod="60 seconds">
  <property name="MY_HOME" value="/home/my" />
  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <File>${MY_HOME}/logs/mylog.log</File>
  </appender> 
</configuration>