动态修改日志级别,太有用了!

背景

我们在系统中一般都会打印一些日志,并且在开发、测试、生产各个环境中的日志级别可能不一样。在开发过程中为了方便调试打印了很多debug日志,但是生产环境为了性能,为了节约存储资源,我们会将日志级别设置为info或error较高的级别,只保留一些关键的必要的日志。

当线上出现问题需要排查时,最有效的方式是分析系统日志。此时因为线上环境日志级别较高,对排查问题有一定的阻碍,为了快速响应线上问题,我们需要更全面的日志帮助排查问题,传统的做法是修改日志级别重启项目。

目标

为了兼顾性能和快速响应线上问题,实现不重启项目的前提下动态修改日志级别。通过使用该功能,可以在需要解决线上问题时,实时调整线上日志输出级别,获取全面的Debug日志,帮助工程师提高定位问题的效率。

技术方案

本文列举了几种实现方案,已经验证可用,供大家参考。

方案一、LoggingSystem

在Spring Boot项目中可以通过LoggingSystem来获取或修改日志配置。

1.1 获取日志Logger配置

通过LoggingSystem API getLoggerConfigurations获取所有Logger配置

List loggerConfigs = loggingSystem.getLoggerConfigurations();

动态修改日志级别,太有用了!

1.2 修改日志级别

通过调用LoggingSystem API setLogLevel设置包或具体Logger的日志级别,修改成功,立即生效。

@Autowired private LoggingSystem loggingSystem;  @RequestMapping(value = "/changeLogLevel", method = RequestMethod.POST) public void changeLogLevel(String loggerName, String newLevel) {     log.info("更新日志级别:{}", newLevel);      LogLevel level = LogLevel.valueOf(newLevel.toUpperCase());      loggingSystem.setLogLevel(loggerName, level);     log.info("更新日志级别:{} 更新完毕", newLevel);     } 

方案二、日志框架提供的API

参考美团技术文章:https://tech.meituan.com/2017/02/17/change-log-level.html

想必现在的业务系统基本都是采用SLF4J日志框架吧,在应用初始化时,SLF4J会绑定具体的日志框架,如Log4j、Logback或Log4j2等。具体源码如下(slf4j-api-1.7.7):

private final static void bind() {   try {     // 查找classpath下所有的StaticLoggerBinder类。     Set<URL> staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet();      reportMultipleBindingAmbiguity(staticLoggerBinderPathSet);     // 每一个slf4j桥接包中都有一个org.slf4j.impl.StaticLoggerBinder类,该类实现了LoggerFactoryBinder接口。     // the next line does the binding     StaticLoggerBinder.getSingleton();     INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION;     reportActualBinding(staticLoggerBinderPathSet);     fixSubstitutedLoggers();     ... } 

findPossibleStaticLoggerBinderPathSet方法用来查找当前classpath下所有的org.slf4j.impl.StaticLoggerBinder类。每一个slf4j桥接包中都有一个StaticLoggerBinder类,该类实现了LoggerFactoryBinder接口。具体绑定到哪一个日志框架则取决于类加载顺序。

动态调整日志级别具体实现步骤如下:

2.1 初始化

确定所使用的日志框架,获取配置文件中所有的Logger内存实例,并将它们的引用缓存到Map容器中。

String type = StaticLoggerBinder.getSingleton().getLoggerFactoryClassStr(); if (LogConstant.LOG4J_LOGGER_FACTORY.equals(type)) {     logFrameworkType = LogFrameworkType.LOG4J;     Enumeration enumeration = org.apache.log4j.LogManager.getCurrentLoggers();     while (enumeration.hasMoreElements()) {         org.apache.log4j.Logger logger = (org.apache.log4j.Logger) enumeration.nextElement();         if (logger.getLevel() != null) {             loggerMap.put(logger.getName(), logger);         }     }     org.apache.log4j.Logger rootLogger = org.apache.log4j.LogManager.getRootLogger();     loggerMap.put(rootLogger.getName(), rootLogger); } else if (LogConstant.LOGBACK_LOGGER_FACTORY.equals(type)) {     logFrameworkType = LogFrameworkType.LOGBACK;     ch.qos.logback.classic.LoggerContext loggerContext = (ch.qos.logback.classic.LoggerContext) LoggerFactory.getILoggerFactory();     for (ch.qos.logback.classic.Logger logger : loggerContext.getLoggerList()) {         if (logger.getLevel() != null) {             loggerMap.put(logger.getName(), logger);         }     }     ch.qos.logback.classic.Logger rootLogger = (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);     loggerMap.put(rootLogger.getName(), rootLogger); } else if (LogConstant.LOG4J2_LOGGER_FACTORY.equals(type)) {     logFrameworkType = LogFrameworkType.LOG4J2;     org.apache.logging.log4j.core.LoggerContext loggerContext = (org.apache.logging.log4j.core.LoggerContext) org.apache.logging.log4j.LogManager.getContext(false);     Map<String, org.apache.logging.log4j.core.config.LoggerConfig> map = loggerContext.getConfiguration().getLoggers();     for (org.apache.logging.log4j.core.config.LoggerConfig loggerConfig : map.values()) {         String key = loggerConfig.getName();         if (StringUtils.isBlank(key)) {             key = "root";         }         loggerMap.put(key, loggerConfig);     } } else {     logFrameworkType = LogFrameworkType.UNKNOWN;     LOG.error("Log框架无法识别: type={}", type); } 

2.2 获取Logger列表

从本地Map容器取出,封装成包含loggerName、logLevel的对象。

private String getLoggerList() {     JSONObject result = new JSONObject();     result.put("logFramework", logFrameworkType);     JSONArray loggerList = new JSONArray();     for (ConcurrentMap.Entry<String, Object> entry : loggerMap.entrySet()) {         JSONObject loggerJSON = new JSONObject();         loggerJSON.put("loggerName", entry.getKey());         if (logFrameworkType == LogFrameworkType.LOG4J) {             org.apache.log4j.Logger targetLogger = (org.apache.log4j.Logger) entry.getValue();             loggerJSON.put("logLevel", targetLogger.getLevel().toString());         } else if (logFrameworkType == LogFrameworkType.LOGBACK) {             ch.qos.logback.classic.Logger targetLogger = (ch.qos.logback.classic.Logger) entry.getValue();             loggerJSON.put("logLevel", targetLogger.getLevel().toString());         } else if (logFrameworkType == LogFrameworkType.LOG4J2) {             org.apache.logging.log4j.core.config.LoggerConfig targetLogger = (org.apache.logging.log4j.core.config.LoggerConfig) entry.getValue();             loggerJSON.put("logLevel", targetLogger.getLevel().toString());         } else {             loggerJSON.put("logLevel", "Logger的类型未知,无法处理!");         }         loggerList.add(loggerJSON);     }     result.put("loggerList", loggerList);     LOG.info("getLoggerList: result={}", result.toString());     return result.toString(); } 

结果:

{     "loggerList": [         {             "logLevel": "OFF",             "loggerName": "org.springframework.ldap"         },         {             "logLevel": "INFO",             "loggerName": "ROOT"         },         {             "logLevel": "OFF",             "loggerName": "com.sun.jersey.api.client"         },         {             "logLevel": "OFF",             "loggerName": "com.netflix.discovery"         }     ],     "logFramework": "LOGBACK" } 

2.3 修改日志级别

通过调用具体的日志框架提供的API setLevel修改Logger日志级别,修改成功,立即生效。

private String setLogLevel(JSONArray data) {     LOG.info("setLogLevel: data={}", data);     List<LoggerBean> loggerList = parseJsonData(data);     if (CollectionUtils.isEmpty(loggerList)) {         return "";     }     for (LoggerBean loggerbean : loggerList) {         Object logger = loggerMap.get(loggerbean.getName());         if (logger == null) {             throw new RuntimeException("需要修改日志级别的Logger不存在");         }         if (logFrameworkType == LogFrameworkType.LOG4J) {             org.apache.log4j.Logger targetLogger = (org.apache.log4j.Logger) logger;             org.apache.log4j.Level targetLevel = org.apache.log4j.Level.toLevel(loggerbean.getLevel());             targetLogger.setLevel(targetLevel);         } else if (logFrameworkType == LogFrameworkType.LOGBACK) {             ch.qos.logback.classic.Logger targetLogger = (ch.qos.logback.classic.Logger) logger;             ch.qos.logback.classic.Level targetLevel = ch.qos.logback.classic.Level.toLevel(loggerbean.getLevel());             targetLogger.setLevel(targetLevel);         } else if (logFrameworkType == LogFrameworkType.LOG4J2) {             org.apache.logging.log4j.core.config.LoggerConfig loggerConfig = (org.apache.logging.log4j.core.config.LoggerConfig) logger;             org.apache.logging.log4j.Level targetLevel = org.apache.logging.log4j.Level.toLevel(loggerbean.getLevel());             loggerConfig.setLevel(targetLevel);             org.apache.logging.log4j.core.LoggerContext ctx = (org.apache.logging.log4j.core.LoggerContext) org.apache.logging.log4j.LogManager.getContext(false);             ctx.updateLoggers(); // This causes all Loggers to refetch information from their LoggerConfig.         } else {             throw new RuntimeException("Logger的类型未知,无法处理!");         }     }     return "success"; } 

方案三、spring-boot-starter-actuator

3.1 引入依赖

<dependency>     <groupId>org.springframework.boot</groupId>     <artifactId>spring-boot-starter-actuator</artifactId> </dependency> 

3.2 开启日志端点配置

# 由于Spring Boot 2.x默认只暴露 /health 以及 /info 端点, # 而日志控制需要用到 /loggers 端点,故而需要设置将其暴露。当然把loggers替换成*也是可以的;开启所有! management:   endpoints:     web:       exposure:         include: 'loggers' 

可以通过访问URL/actuator/loggers/后加包名或者类名来查询指定包或者类的当前日志级别。

curl http://127.0.0.1:8007/manage/actuator/loggers/com.trrt.ep {"configuredLevel":"DEBUG","effectiveLevel":"DEBUG"} 

3.3 查看所有Logger

http://127.0.0.1:8007/manage/actuator/loggers

动态修改日志级别,太有用了!

3.4 修改日志级别

可以通过访问URL/actuator/loggers/后加包名或者类名来修改指定包或者类的当前日志级别。

curl -X POST "http://127.0.0.1:8007/manage/actuator/loggers/com.trrt.ep" -H "Content-Type: application/json;charset=UTF-8" --data '{"configuredLevel":"debug"}'

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