springcloud通过apollo动态配置logback

注：文中例子基于apollo官方提供的demo修改。
1.application.properties配置

app.id=spring-cloud-logger
# set apollo meta server address, adjust to actual address if necessary
apollo.meta=http://localhost:8080
apollo.bootstrap.enabled=true
apollo.bootstrap.namespaces=application
apollo.bootstrap.eagerLoad.enabled=true
logging.config=classpath:logback-test.xml

通过apollo.bootstrap.eagerLoad.enabled=true来使Apollo的加载顺序放到日志系统加载之前，这样就能保证日志组件加载spring的配置。

2.logback-test.xml配置

<?xml version="1.0" encoding="UTF-8"?>

<configuration>
    <springProperty scope="context" name="LOG_HOME" source="log.test.loghome" defaultValue="D:\\log\\"/>

    <!--控制台输出appender-->
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <!--设置输出格式-->
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
            <charset>UTF-8</charset>
        </encoder>
    </appender>

     <appender name="file" class="ch.qos.logback.core.rolling.RollingFileAppender">
            <file>${LOG_HOME}/test.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <FileNamePattern>${LOG_HOME}/test.log.%d{yyyy-MM-dd_HH}</FileNamePattern>
            <MaxHistory>10</MaxHistory>
        </rollingPolicy>
       <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
                <charset>UTF-8</charset>
            </encoder>
    </appender>

     <root level="DEBUG">
        <appender-ref ref="console"/>
        <appender-ref ref="file"/>
     </root>

</configuration>

3.开启apollo配置类

package com;

import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
@EnableApolloConfig
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

4.配置动态生效核心类
目前logback只能通过日志文件动态刷新，怎么通过apollo配置修改属性动态生效？
目前通过apollo能动态生效的也只有日志级别。
如果其他配置想通过apollo动态生效，如demo中的路径等配置，可以通过以下方式，当logback使用的spring变量发现修改后，可以重新初始化logback配置就能达到目标效果。

例如：
通过在apollo配置以下属性，可以让日志级别动态生效：

 logging.level.com.test = warn

其他非日志级别属性，我们可以统一使用一个前缀地址，监听该前缀，当配置发现变化后，执行下面例子中的代码可以让logback动态生效。

package com;

import com.ctrip.framework.apollo.Config;
import com.ctrip.framework.apollo.model.ConfigChangeEvent;
import com.ctrip.framework.apollo.spring.annotation.ApolloConfig;
import com.ctrip.framework.apollo.spring.annotation.ApolloConfigChangeListener;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.logging.LoggingInitializationContext;
import org.springframework.boot.logging.LoggingSystem;
import org.springframework.cloud.context.environment.EnvironmentChangeEvent;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Service;
import org.springframework.util.ResourceUtils;

import javax.annotation.PostConstruct;
import java.util.Set;

@Service
public class LoggerLevelRefresher implements ApplicationContextAware, EnvironmentAware {

  private ApplicationContext applicationContext;
  private ConfigurableEnvironment environment;

  @Autowired
  private LoggingSystem loggingSystem;

  @ApolloConfig
  private Config config;

  @PostConstruct
  private void initialize() {
    refreshLoggingLevels(config.getPropertyNames());
  }

  @ApolloConfigChangeListener
  private void onChange(ConfigChangeEvent changeEvent) {
    refreshLoggingLevels(changeEvent.changedKeys());
  }

  @ApolloConfigChangeListener(interestedKeyPrefixes = {"log.test."})
  private void onChangeLog(ConfigChangeEvent changeEvent) {
    LoggingInitializationContext initializationContext = new LoggingInitializationContext(environment);
    String logConfig = environment.getProperty("logging.config");
    try{
      ResourceUtils.getURL(logConfig).openStream().close();
      loggingSystem.cleanUp();
      loggingSystem.initialize(initializationContext, logConfig, null);
    }catch (Exception e){
    }
  }

  private void refreshLoggingLevels(Set<String> changedKeys) {
    System.out.println("Refreshing logging levels");

    /**
     * refresh logging levels
     * @see org.springframework.cloud.logging.LoggingRebinder#onApplicationEvent
     */
    this.applicationContext.publishEvent(new EnvironmentChangeEvent(changedKeys));

    System.out.println("Logging levels refreshed");
  }

  @Override
  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    this.applicationContext = applicationContext;
  }

  @Override
  public void setEnvironment(Environment environment) {
    this.environment = (ConfigurableEnvironment) environment;
  }
}

5.github代码地址

[https://github.com/495804928/logger](https://github.com/495804928/logger)