聊聊springboot2的LoggersEndpoint

序

本文主要研究下springboot2的LoggersEndpoint

實例

• GET /actuator/loggers

{
  "levels": [
    "OFF",
    "ERROR",
    "WARN",
    "INFO",
    "DEBUG",
    "TRACE"
  ],
  "loggers": {
    "ROOT": {
      "configuredLevel": "INFO",
      "effectiveLevel": "INFO"
    },
    "com": {
      "configuredLevel": null,
      "effectiveLevel": "INFO"
    },
    "com.example": {
      "configuredLevel": null,
      "effectiveLevel": "INFO"
    },
    "com.example.config": {
      "configuredLevel": null,
      "effectiveLevel": "INFO"
    }
  }
}

• GET /actuator/loggers/com.example

{
  "configuredLevel": null,
  "effectiveLevel": "INFO"
}

• POST

curl -i -X POST -H 'Content-Type: application/json' -d '{"configuredLevel": "ERROR"}' http://localhost:8080/actuator/loggers/com.example
HTTP/1.1 204
Date: Wed, 25 Apr 2018 14:54:41 GMT

LoggersEndpointAutoConfiguration

spring-boot-actuator-autoconfigure-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/autoconfigure/logging/LoggersEndpointAutoConfiguration.java

@Configuration
public class LoggersEndpointAutoConfiguration {

	@Bean
	@ConditionalOnBean(LoggingSystem.class)
	@Conditional(OnEnabledLoggingSystemCondition.class)
	@ConditionalOnMissingBean
	@ConditionalOnEnabledEndpoint
	public LoggersEndpoint loggersEndpoint(LoggingSystem loggingSystem) {
		return new LoggersEndpoint(loggingSystem);
	}

	static class OnEnabledLoggingSystemCondition extends SpringBootCondition {

		@Override
		public ConditionOutcome getMatchOutcome(ConditionContext context,
				AnnotatedTypeMetadata metadata) {
			ConditionMessage.Builder message = ConditionMessage
					.forCondition("Logging System");
			String loggingSystem = System.getProperty(LoggingSystem.SYSTEM_PROPERTY);
			if (LoggingSystem.NONE.equals(loggingSystem)) {
				return ConditionOutcome.noMatch(message.because("system property "
						+ LoggingSystem.SYSTEM_PROPERTY + " is set to none"));
			}
			return ConditionOutcome.match(message.because("enabled"));
		}

	}

}

這裏根據loggingSystem，來建立LoggersEndpoint；另外還使用了OnEnabledLoggingSystemCondition

LoggersEndpoint

spring-boot-actuator-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/logging/LoggersEndpoint.java

@Endpoint(id = "loggers")
public class LoggersEndpoint {

	private final LoggingSystem loggingSystem;

	/**
	 * Create a new {@link LoggersEndpoint} instance.
	 * @param loggingSystem the logging system to expose
	 */
	public LoggersEndpoint(LoggingSystem loggingSystem) {
		Assert.notNull(loggingSystem, "LoggingSystem must not be null");
		this.loggingSystem = loggingSystem;
	}

	@ReadOperation
	public Map<String, Object> loggers() {
		Collection<LoggerConfiguration> configurations = this.loggingSystem
				.getLoggerConfigurations();
		if (configurations == null) {
			return Collections.emptyMap();
		}
		Map<String, Object> result = new LinkedHashMap<>();
		result.put("levels", getLevels());
		result.put("loggers", getLoggers(configurations));
		return result;
	}

	@ReadOperation
	public LoggerLevels loggerLevels(@Selector String name) {
		Assert.notNull(name, "Name must not be null");
		LoggerConfiguration configuration = this.loggingSystem
				.getLoggerConfiguration(name);
		return (configuration == null ? null : new LoggerLevels(configuration));
	}

	@WriteOperation
	public void configureLogLevel(@Selector String name,
			@Nullable LogLevel configuredLevel) {
		Assert.notNull(name, "Name must not be empty");
		this.loggingSystem.setLogLevel(name, configuredLevel);
	}

	private NavigableSet<LogLevel> getLevels() {
		Set<LogLevel> levels = this.loggingSystem.getSupportedLogLevels();
		return new TreeSet<>(levels).descendingSet();
	}

	private Map<String, LoggerLevels> getLoggers(
			Collection<LoggerConfiguration> configurations) {
		Map<String, LoggerLevels> loggers = new LinkedHashMap<>(configurations.size());
		for (LoggerConfiguration configuration : configurations) {
			loggers.put(configuration.getName(), new LoggerLevels(configuration));
		}
		return loggers;
	}

	/**
	 * Levels configured for a given logger exposed in a JSON friendly way.
	 */
	public static class LoggerLevels {

		private String configuredLevel;

		private String effectiveLevel;

		public LoggerLevels(LoggerConfiguration configuration) {
			this.configuredLevel = getName(configuration.getConfiguredLevel());
			this.effectiveLevel = getName(configuration.getEffectiveLevel());
		}

		private String getName(LogLevel level) {
			return (level == null ? null : level.name());
		}

		public String getConfiguredLevel() {
			return this.configuredLevel;
		}

		public String getEffectiveLevel() {
			return this.effectiveLevel;
		}

	}

}

經過loggingSystem.getLoggerConfigurations()獲取Collection<LoggerConfiguration>，而後getLoggers方法將configurations轉換爲Map<String, LoggerLevels>

小結

LoggersEndpoint提供兩個readOperation和一個writeOperation，分別用來讀取和更改logger的level，很是實用。

doc

• Spring Boot Reference Guide