1 日志级别

Spring Boot Actuator包括在运行时查看和配置应用程序日志级别的功能。您可以查看整个列表，也可以查看单个记录器的配置，该配置由显式配置的日志级别和日志框架给出的有效日志级别组成。这些级别可以是:

• TRACE
• DEBUG
• INFO
• WARN
• ERROR
• FATAL
• OFF
• null

null表示没有显式配置。

2 logger接口

2.1 列表

GET /loggers

样例:
GET http://localhost:8087/actuator/loggers
Authorization: Basic dGVzdDpCQUtGWCQzbA==

2.2 详情

GET /loggers/{name:.*}

样例:
GET http://localhost:8087/actuator/loggers/sample.actuator.SampleActuatorApplication
Authorization: Basic dGVzdDpCQUtGWCQzbA==

2.3 修改level

POST /loggers/{name:.*}

样例:
POST http://localhost:8087/actuator/loggers/sample.actuator.SampleActuatorApplication
Authorization: Basic dGVzdDpCQUtGWCQzbA==
Content-Type: application/json

{
“configuredLevel”: “DEBUG”
}

3 分析

接口位于spring boot actuator 的LoggersMvcEndpoint
LoggersMvcEndpoint->LoggersEndpoint->LoggingSystem

3.1 LoggingSystem

LoggingSystem是接口，通过实现类具体处理

LoggingSystem实现类是通过LoggingSystem.get(get(ClassLoader classLoader)获得的

    private static final Map<String, String> SYSTEMS;static {// LinkedHashMap 保证顺序性，logback、log4j、javalogging的顺序，加载到对应的类，就返回对应的LoggingSystem的实现类Map<String, String> systems = new LinkedHashMap<String, String>();systems.put("ch.qos.logback.core.Appender", "org.springframework.boot.logging.logback.LogbackLoggingSystem");systems.put("org.apache.logging.log4j.core.impl.Log4jContextFactory","org.springframework.boot.logging.log4j2.Log4J2LoggingSystem");systems.put("java.util.logging.LogManager", "org.springframework.boot.logging.java.JavaLoggingSystem");SYSTEMS = Collections.unmodifiableMap(systems);}public static LoggingSystem get(ClassLoader classLoader) {String loggingSystem = System.getProperty(SYSTEM_PROPERTY);if (StringUtils.hasLength(loggingSystem)) {if (NONE.equals(loggingSystem)) {return new NoOpLoggingSystem();}return get(classLoader, loggingSystem);}for (Map.Entry<String, String> entry : SYSTEMS.entrySet()) {if (ClassUtils.isPresent(entry.getKey(), classLoader)) {return get(classLoader, entry.getValue());}}throw new IllegalStateException("No suitable logging system located");}private static LoggingSystem get(ClassLoader classLoader, String loggingSystemClass) {try {Class<?> systemClass = ClassUtils.forName(loggingSystemClass, classLoader);return (LoggingSystem) systemClass.getConstructor(ClassLoader.class).newInstance(classLoader);}catch (Exception ex) {throw new IllegalStateException(ex);}}

LoggingSystem.get(get(ClassLoader classLoader)是通过LoggingApplicationListener调用的

3.2 LoggingApplicationListener

LoggingApplicationListener类图如下

在spring.factories发现LoggingApplicationListener配置，通过SpringFactoryLoader加载

初始化流程

注册到spring

调用流程

4 问题

4.1 安全

http接口可能会暴漏出去，存在安全问题。可以参照https://blog.csdn.net/weixin_43511928/article/details/129131251

• 指定management.port，独立于业务端口
• security.user.name、security.user.password配置账号密码(密码要使用强密码)

4.2 缺少reset

日志级别重置，恢复现场。

• 可以在setLogLevel记录被修改的名字、旧的日志级别
• 提供/logger/reset接口，setLogLevel恢复列表

4.3 只支持spring boot

4.3.1 参照对应日志框架LoggingSystem setLogLevel实现

LogbackLoggingSystem

	@Overridepublic void setLogLevel(String loggerName, LogLevel level) {ch.qos.logback.classic.Logger logger = getLogger(loggerName);if (logger != null) {logger.setLevel(LEVELS.convertSystemToNative(level));}}

Log4J2LoggingSystem

	@Overridepublic void setLogLevel(String loggerName, LogLevel logLevel) {Level level = LEVELS.convertSystemToNative(logLevel);LoggerConfig loggerConfig = getLoggerConfig(loggerName);if (loggerConfig == null) {loggerConfig = new LoggerConfig(loggerName, level, true);getLoggerContext().getConfiguration().addLogger(loggerName, loggerConfig);}else {loggerConfig.setLevel(level);}getLoggerContext().updateLoggers();}

4.3.2 使用arthas修改

参照 https://arthas.aliyun.com/doc/logger.html