聊聊spring cloud的HystrixAutoConfiguration

序

本文主要研究一下spring cloud的HystrixAutoConfiguration

HystrixAutoConfiguration

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixAutoConfiguration.java

/**
 * Auto configuration for Hystrix.
 *
 * @author Christian Dupuis
 * @author Dave Syer
 */
@Configuration
@ConditionalOnClass({ Hystrix.class, HealthIndicator.class })
@AutoConfigureAfter({ HealthIndicatorAutoConfiguration.class })
public class HystrixAutoConfiguration {

	@Bean
	@ConditionalOnEnabledHealthIndicator("hystrix")
	public HystrixHealthIndicator hystrixHealthIndicator() {
		return new HystrixHealthIndicator();
	}

	@Bean
	@ConditionalOnProperty(value = "management.metrics.hystrix.enabled", matchIfMissing = true)
	public HystrixMetricsBinder hystrixMetricsBinder() {
		return new HystrixMetricsBinder();
	}

	/**
	 * See original {@link org.springframework.boot.actuate.autoconfigure.jolokia.JolokiaEndpointAutoConfiguration}
	 */
	@Configuration
	@ConditionalOnWebApplication(type = SERVLET)
	@ConditionalOnBean(HystrixCommandAspect.class) // only install the stream if enabled
	@ConditionalOnClass({ HystrixMetricsStreamServlet.class })
	@EnableConfigurationProperties(HystrixProperties.class)
	protected static class HystrixServletAutoConfiguration {

		@Bean
		@ConditionalOnEnabledEndpoint
		public HystrixStreamEndpoint hystrixStreamEndpoint(HystrixProperties properties) {
			return new HystrixStreamEndpoint(properties.getConfig());
		}

		@Bean
		public HasFeatures hystrixStreamFeature() {
			return HasFeatures.namedFeature("Hystrix Stream Servlet", HystrixMetricsStreamServlet.class);
		}
	}

	@Configuration
	@ConditionalOnWebApplication(type = REACTIVE)
	@ConditionalOnBean(HystrixCommandAspect.class) // only install the stream if enabled
	@ConditionalOnClass({ DispatcherHandler.class })
	@EnableConfigurationProperties(HystrixProperties.class)
	protected static class HystrixWebfluxManagementContextConfiguration {

		@Bean
		@ConditionalOnEnabledEndpoint
		public HystrixWebfluxEndpoint hystrixWebfluxController() {
			Observable<String> serializedDashboardData = HystrixDashboardStream.getInstance().observe()
					.concatMap(dashboardData -> Observable.from(SerialHystrixDashboardData.toMultipleJsonStrings(dashboardData)));
			Publisher<String> publisher = RxReactiveStreams.toPublisher(serializedDashboardData);
			return new HystrixWebfluxEndpoint(publisher);
		}

		@Bean
		public HasFeatures hystrixStreamFeature() {
			return HasFeatures.namedFeature("Hystrix Stream Webflux", HystrixWebfluxEndpoint.class);
		}
	}
}
複製代碼

這裏有幾個bean，一個是HystrixHealthIndicator，還有HystrixMetricsBinder。另外關於endpoint，區分了servlet及webflux版本。

HystrixHealthIndicator

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixHealthIndicator.java

/**
 * A {@link HealthIndicator} implementation for Hystrix circuit breakers.
 * <p>
 * This default implementation will not change the system state (e.g.  <code>OK</code>) but
 * includes all open circuits by name.
 *
 * @author Christian Dupuis
 */
public class HystrixHealthIndicator extends AbstractHealthIndicator {

	private static final Status CIRCUIT_OPEN = new Status("CIRCUIT_OPEN");

	@Override
	protected void doHealthCheck(Builder builder) throws Exception {
		List<String> openCircuitBreakers = new ArrayList<>();

		// Collect all open circuit breakers from Hystrix
		for (HystrixCommandMetrics metrics : HystrixCommandMetrics.getInstances()) {
			HystrixCircuitBreaker circuitBreaker = HystrixCircuitBreaker.Factory
					.getInstance(metrics.getCommandKey());
			if (circuitBreaker != null && circuitBreaker.isOpen()) {
				openCircuitBreakers.add(metrics.getCommandGroup().name() + "::"
						+ metrics.getCommandKey().name());
			}
		}

		// If there is at least one open circuit report OUT_OF_SERVICE adding the command
		// group
		// and key name
		if (!openCircuitBreakers.isEmpty()) {
			builder.status(CIRCUIT_OPEN).withDetail("openCircuitBreakers",
					openCircuitBreakers);
		}
		else {
			builder.up();
		}
	}

}
複製代碼

檢查斷路器的狀態

HystrixMetricsBinder

micrometer-core-1.0.5-sources.jar!/io/micrometer/core/instrument/binder/hystrix/HystrixMetricsBinder.java

@NonNullApi
@NonNullFields
public class HystrixMetricsBinder implements MeterBinder {

    @Override
    public void bindTo(MeterRegistry registry) {
        // Keeps references of existing Hystrix plugins.
        HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance().getEventNotifier();
        HystrixPropertiesStrategy propertiesStrategy = HystrixPlugins.getInstance().getPropertiesStrategy();
        HystrixCommandExecutionHook commandExecutionHook = HystrixPlugins.getInstance().getCommandExecutionHook();
        HystrixConcurrencyStrategy concurrencyStrategy = HystrixPlugins.getInstance().getConcurrencyStrategy();

        HystrixPlugins.reset();

        // Registers existing plugins except the new MicroMeter Strategy plugin.
        HystrixPlugins.getInstance().registerMetricsPublisher(new MicrometerMetricsPublisher(registry));
        HystrixPlugins.getInstance().registerConcurrencyStrategy(concurrencyStrategy);
        HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
        HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
        HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);
    }
}
複製代碼

這裏導出metrics到micrometer

HystrixStreamEndpoint

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixStreamEndpoint.java

/**
 * {@link org.springframework.boot.actuate.endpoint.annotation.Endpoint} to expose a Jolokia {@link HystrixMetricsStreamServlet}.
 *
 * @author Phillip Webb
 * @since 2.0.0
 */
@ServletEndpoint(id = "hystrix.stream")
public class HystrixStreamEndpoint implements Supplier<EndpointServlet> {

    private final Map<String, String> initParameters;

    public HystrixStreamEndpoint(Map<String, String> initParameters) {
        this.initParameters = initParameters;
    }

    @Override
    public EndpointServlet get() {
        return new EndpointServlet(HystrixMetricsStreamServlet.class)
                .withInitParameters(this.initParameters);
    }
}
複製代碼

這個是基於servlet的

HystrixWebfluxEndpoint

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixWebfluxEndpoint.java

@RestControllerEndpoint(id = "hystrix.stream")
public class HystrixWebfluxEndpoint {

    private final Flux<String> stream;

    public HystrixWebfluxEndpoint(Publisher<String> dashboardData) {
        stream = Flux.interval(Duration.ofMillis(500)).map(aLong -> "{\"type\":\"ping\"}")
                .mergeWith(dashboardData).share();
    }

    // path needs to be empty, so it registers correct as /actuator/hystrix.stream
    @GetMapping(path = "", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<String> hystrixStream() {
        return stream;
    }
}
複製代碼

這個是基於webflux的

小結

HystrixAutoConfiguration主要是配置了HystrixHealthIndicator、HystrixMetricsBinder以及HystrixEndpoint(分servlet與webflux版本)。

doc

• 14. Circuit Breaker: Hystrix Dashboard