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
在这里插入图片描述
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
在这里插入图片描述
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

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

Log4J2LoggingSystem

	@Override
	public 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();
	}