Spring Cloud之Ribbon配置和源码分析

于 2021-07-19 17:54:43 发布
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分类专栏： Spring Cloud 文章标签： spring cloud ribbon
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本文链接：https://blog.youkuaiyun.com/gu19930914/article/details/118906096
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文章目录

1. 负载均衡介绍

负载均衡一般分为两种

  • 服务端负载均衡
    • Nginx
    • F5(硬件设备)
  • 客户端负载均衡
    • Ribbon

2. Ribbon负载均衡策略

  • com.netflix.loadbalancer.RoundRobinRule

    轮询方式，默认方式

  • com.netflix.loadbalancer.RandomRule

    随机方式

  • com.netflix.loadbalancer.RetryRule

    轮询重试方式，重试默认采用的也是轮询

  • com.netflix.loadbalancer.WeightedResponseTimeRule

    权重方式，以响应时间决定每个服务的权重，一般响应时间越短权重越高

  • com.netflix.loadbalancer.BestAvailableRule

    最优方式，一般选择并发数最小的服务

  • com.netflix.loadbalancer.AvailabilityFilteringRule

    可用性过滤方式，过滤掉那些根据特定规则（如：连接不上、并发数超过阀值）而不可用的服务，再在剩余服务中选择

  • com.netflix.loadbalancer.ZoneAvoidanceRule

    区域性过滤 + 可用性过滤


3. Ribbon失败重试机制

方案一：使用对RestTemplate添加拦截器的方式

  1. 引入spring-retry包

    <dependency>
  <groupId>org.springframework.retry</groupId>
  <artifactId>spring-retry</artifactId>
</dependency>

  2. 使用@LoadBalanced注解修饰RestTemplate实例的声明

    /**
 * 在使用Ribbon负载均衡时必须使用@LoadBalanced注解
 */
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
    // 配置超时时间
    SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
    factory.setConnectTimeout(2000);
    factory.setReadTimeout(3000);
    return new RestTemplate(factory);
}

  3. 对服务之间调用进行负载均衡配置和失败重试配置

    全局配置

    ribbon:
  # 负载均衡配置
  NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule
  # 无论什么类型请求失败都进行重试, 否则只会对GET请求重试
  OkToRetryOnAllOperations: false
  # 切换服务的重试次数
  MaxAutoRetriesNextServer: 2
  # 对当前服务的重试次数
  MaxAutoRetries: 0
  
  # 连接超时时间(该配置在此方式中无效, 可采用在声明RestTemplate实例时进行超时时间的全局配置, 如上点)
  # ConnectTimeout: 2000
  # 请求超时时间(该配置在此方式中无效, 可采用在声明RestTemplate实例时进行超时时间的全局配置, 如上点)
  # ReadTimeout: 3000

    针对某个服务配置

    # 这个服务的名称
application-name:
  ribbon:
    # 负载均衡配置
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule
    # 无论什么类型请求失败都进行重试, 否则只会对GET请求重试
    OkToRetryOnAllOperations: false
    # 切换服务的重试次数
    MaxAutoRetriesNextServer: 2
    # 对当前服务的重试次数
    MaxAutoRetries: 0
    
    # 连接超时时间(该配置在此方式中无效)
    # ConnectTimeout: 2000
    # 请求超时时间(该配置在此方式中无效)
    # ReadTimeout: 3000

  4. 源码分析

    1. 以@LoadBalanced注解作为入口，可得知该注解所在jar包的spring自动装配配置文件spring.factories如下
    # AutoConfiguration
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.client.CommonsClientAutoConfiguration,\
org.springframework.cloud.client.ReactiveCommonsClientAutoConfiguration,\
org.springframework.cloud.client.discovery.composite.CompositeDiscoveryClientAutoConfiguration,\
org.springframework.cloud.client.discovery.composite.reactive.ReactiveCompositeDiscoveryClientAutoConfiguration,\
org.springframework.cloud.client.discovery.noop.NoopDiscoveryClientAutoConfiguration,\
org.springframework.cloud.client.discovery.simple.SimpleDiscoveryClientAutoConfiguration,\
org.springframework.cloud.client.discovery.simple.reactive.SimpleReactiveDiscoveryClientAutoConfiguration,\
org.springframework.cloud.client.hypermedia.CloudHypermediaAutoConfiguration,\
org.springframework.cloud.client.loadbalancer.AsyncLoadBalancerAutoConfiguration,\
# 这个类就是我们要找的负载均衡的自动配置类
org.springframework.cloud.client.loadbalancer.LoadBalancerAutoConfiguration,\
org.springframework.cloud.client.loadbalancer.reactive.LoadBalancerBeanPostProcessorAutoConfiguration,\
org.springframework.cloud.client.loadbalancer.reactive.ReactorLoadBalancerClientAutoConfiguration,\
org.springframework.cloud.client.loadbalancer.reactive.ReactiveLoadBalancerAutoConfiguration,\
org.springframework.cloud.client.serviceregistry.ServiceRegistryAutoConfiguration,\
org.springframework.cloud.commons.httpclient.HttpClientConfiguration,\
org.springframework.cloud.commons.util.UtilAutoConfiguration,\
org.springframework.cloud.configuration.CompatibilityVerifierAutoConfiguration,\
org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration
# Environment Post Processors
org.springframework.boot.env.EnvironmentPostProcessor=\
org.springframework.cloud.client.HostInfoEnvironmentPostProcessor
# Failure Analyzers
org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.cloud.configuration.CompatibilityNotMetFailureAnalyzer
    1. LoadBalancerAutoConfiguration源码如下
    @Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RestTemplate.class)
@ConditionalOnBean(LoadBalancerClient.class)
@EnableConfigurationProperties(LoadBalancerRetryProperties.class)
public class LoadBalancerAutoConfiguration {

    /**
     * 注入我们声明RestTemplate实例
     */
	@LoadBalanced
	@Autowired(required = false)
	private List<RestTemplate> restTemplates = Collections.emptyList();

	@Autowired(required = false)
	private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();

	@Bean
	public SmartInitializingSingleton loadBalancedRestTemplateInitializerDeprecated(
			final ObjectProvider<List<RestTemplateCustomizer>> restTemplateCustomizers) {
		return () -> restTemplateCustomizers.ifAvailable(customizers -> {
			for (RestTemplate restTemplate : LoadBalancerAutoConfiguration.this.restTemplates) {
				for (RestTemplateCustomizer customizer : customizers) {
                    /*
                     * 步骤 6
                     * 对RestTemplate实例进行自定义配置
                     */
					customizer.customize(restTemplate);
				}
			}
		});
	}

    /**
     * 步骤 4
     * 创建LoadBalancerRequestFactory(负载均衡请求工厂)实例, 并注入LoadBalancerClient实例
     */
	@Bean
	@ConditionalOnMissingBean
	public LoadBalancerRequestFactory loadBalancerRequestFactory(
			LoadBalancerClient loadBalancerClient) {
		return new LoadBalancerRequestFactory(loadBalancerClient, this.transformers);
	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnMissingClass("org.springframework.retry.support.RetryTemplate")
	static class LoadBalancerInterceptorConfig {

		//......

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(RetryTemplate.class)
	public static class RetryAutoConfiguration {

		//......

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(RetryTemplate.class)
	public static class RetryInterceptorAutoConfiguration {

        /**
         * 步骤 5
         * 创建RetryLoadBalancerInterceptor(重试负载均衡拦截器)实例, 并注入LoadBalancerClient、LoadBalancerRequestFactory、LoadBalancedRetryFactory等实例
         */
		@Bean
		@ConditionalOnMissingBean
		public RetryLoadBalancerInterceptor loadBalancerRetryInterceptor(
				LoadBalancerClient loadBalancerClient,
				LoadBalancerRetryProperties properties,
				LoadBalancerRequestFactory requestFactory,
				LoadBalancedRetryFactory loadBalancedRetryFactory) {
			return new RetryLoadBalancerInterceptor(loadBalancerClient, properties,
					requestFactory, loadBalancedRetryFactory);
		}

		@Bean
		@ConditionalOnMissingBean
		public RestTemplateCustomizer restTemplateCustomizer(
				final RetryLoadBalancerInterceptor loadBalancerInterceptor) {
			return restTemplate -> {
				List<ClientHttpRequestInterceptor> list = new ArrayList<>(
						restTemplate.getInterceptors());
                /*
                 * 步骤 7
                 * 对RestTemplate实例进行添加RetryLoadBalancerInterceptor(重试负载均衡拦截器)
                 */
				list.add(loadBalancerInterceptor);
				restTemplate.setInterceptors(list);
			};
		}

	}

}
    1. 再根据Spring Cloud Netflix Ribbon源码中的spring.factories配置文件，可找到Ribbon的自动配置类RibbonAutoConfiguration
    org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration

    @Configuration
@Conditional(RibbonAutoConfiguration.RibbonClassesConditions.class)
@RibbonClients
@AutoConfigureAfter(
		name = "org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration")
// 声明该配置类在LoadBalancerAutoConfiguration加载之前进行加载
@AutoConfigureBefore({ LoadBalancerAutoConfiguration.class,
		AsyncLoadBalancerAutoConfiguration.class })
@EnableConfigurationProperties({ RibbonEagerLoadProperties.class,
		ServerIntrospectorProperties.class })
@ConditionalOnProperty(value = "spring.cloud.loadbalancer.ribbon.enabled",
		havingValue = "true", matchIfMissing = true)
public class RibbonAutoConfiguration {

	@Autowired(required = false)
	private List<RibbonClientSpecification> configurations = new ArrayList<>();

	@Autowired
	private RibbonEagerLoadProperties ribbonEagerLoadProperties;

	@Bean
	public HasFeatures ribbonFeature() {
		return HasFeatures.namedFeature("Ribbon", Ribbon.class);
	}

    /**
     * 步骤 1
     * 创建SpringClientFactory(Spring客户端工厂)实例, 并注入相关配置
     */
	@Bean
	@ConditionalOnMissingBean
	public SpringClientFactory springClientFactory() {
		SpringClientFactory factory = new SpringClientFactory();
		factory.setConfigurations(this.configurations);
		return factory;
	}

    /**
     * 步骤 2
     * 创建LoadBalancerClient(负载均衡客户端)实例, 并注入SpringClientFactory实例
     */
	@Bean
	@ConditionalOnMissingBean(LoadBalancerClient.class)
	public LoadBalancerClient loadBalancerClient() {
		return new RibbonLoadBalancerClient(springClientFactory());
	}

    /**
     * 步骤 3
     * 创建LoadBalancedRetryFactory(负载均衡重试工厂)实例, 并注入SpringClientFactory实例
     */
	@Bean
	@ConditionalOnClass(name = "org.springframework.retry.support.RetryTemplate")
	@ConditionalOnMissingBean
	public LoadBalancedRetryFactory loadBalancedRetryPolicyFactory(
			final SpringClientFactory clientFactory) {
		return new RibbonLoadBalancedRetryFactory(clientFactory);
	}

	@Bean
	@ConditionalOnMissingBean
	public PropertiesFactory propertiesFactory() {
		return new PropertiesFactory();
	}

	@Bean
	@ConditionalOnProperty("ribbon.eager-load.enabled")
	public RibbonApplicationContextInitializer ribbonApplicationContextInitializer() {
		return new RibbonApplicationContextInitializer(springClientFactory(),
				ribbonEagerLoadProperties.getClients());
	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(HttpRequest.class)
	@ConditionalOnRibbonRestClient
	protected static class RibbonClientHttpRequestFactoryConfiguration {

		//......

	}

	@Target({ ElementType.TYPE, ElementType.METHOD })
	@Retention(RetentionPolicy.RUNTIME)
	@Documented
	@Conditional(OnRibbonRestClientCondition.class)
	@interface ConditionalOnRibbonRestClient {

	}

	private static class OnRibbonRestClientCondition extends AnyNestedCondition {

		//......

	}

	static class RibbonClassesConditions extends AllNestedConditions {

		//......

	}

}

方案二：使用Ribbon的RestClient的方式

  1. 使用@LoadBalanced注解修饰RestTemplate实例的声明

    /**
 * 在使用Ribbon负载均衡时必须使用@LoadBalanced注解
 */
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
    return new RestTemplate();
}

  2. 对服务之间调用进行负载均衡配置和失败重试配置

    ribbon:
  restclient:
    # 启用Ribbon的RestClient, 必须配置该项
    enabled: true
  eager-load:
    # 对以下服务的Ribbon客户端进行饥饿加载, 以逗号隔开
    clients: application-name1,application-name2

    全局配置

    ribbon:
  # 负载均衡配置
  NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule
  # 无论什么类型请求失败都进行重试, 否则只会对GET请求重试
  OkToRetryOnAllOperations: false
  # 切换服务的重试次数
  MaxAutoRetriesNextServer: 2
  # 对当前服务的重试次数
  MaxAutoRetries: 0
  # 连接超时时间
  ConnectTimeout: 2000
  # 请求超时时间
  ReadTimeout: 3000

    针对某个服务配置

    # 这个服务的名称
application-name:
  ribbon:
    # 负载均衡配置
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule
    # 无论什么类型请求失败都进行重试, 否则只会对GET请求重试
    OkToRetryOnAllOperations: false
    # 切换服务的重试次数
    MaxAutoRetriesNextServer: 2
    # 对当前服务的重试次数
    MaxAutoRetries: 0
    # 连接超时时间
    ConnectTimeout: 2000
    # 请求超时时间
    ReadTimeout: 3000

  3. 源码分析

    i) 根据LoadBalancerAutoConfiguration类和RibbonAutoConfiguration类重新分析，如下：

    @Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RestTemplate.class)
@ConditionalOnBean(LoadBalancerClient.class)
@EnableConfigurationProperties(LoadBalancerRetryProperties.class)
public class LoadBalancerAutoConfiguration {

    /**
     * 注入我们声明RestTemplate实例
     */
	@LoadBalanced
	@Autowired(required = false)
	private List<RestTemplate> restTemplates = Collections.emptyList();

	@Autowired(required = false)
	private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();

	@Bean
	public SmartInitializingSingleton loadBalancedRestTemplateInitializerDeprecated(
			final ObjectProvider<List<RestTemplateCustomizer>> restTemplateCustomizers) {
		return () -> restTemplateCustomizers.ifAvailable(customizers -> {
			for (RestTemplate restTemplate : LoadBalancerAutoConfiguration.this.restTemplates) {
				for (RestTemplateCustomizer customizer : customizers) {
                    /*
                     * 步骤 7
                     * 对RestTemplate实例进行自定义配置
                     */
					customizer.customize(restTemplate);
				}
			}
		});
	}

    /**
     * 步骤 5
     * 创建LoadBalancerRequestFactory(负载均衡请求工厂)实例, 并注入LoadBalancerClient实例
     * 无意义
     */
	@Bean
	@ConditionalOnMissingBean
	public LoadBalancerRequestFactory loadBalancerRequestFactory(
			LoadBalancerClient loadBalancerClient) {
		return new LoadBalancerRequestFactory(loadBalancerClient, this.transformers);
	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnMissingClass("org.springframework.retry.support.RetryTemplate")
	static class LoadBalancerInterceptorConfig {

		//......

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(RetryTemplate.class)
	public static class RetryAutoConfiguration {

		//......

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(RetryTemplate.class)
	public static class RetryInterceptorAutoConfiguration {

        /**
         * 步骤 6
         * 创建RetryLoadBalancerInterceptor(重试负载均衡拦截器)实例, 并注入LoadBalancerClient、LoadBalancerRequestFactory、LoadBalancedRetryFactory等实例
         * 因为该拦截器并不会注入到RestTemplate实例中, 所以创建出来也并不会应用到程序运行中, 从而导致第3、4、5步创建的实例都无意义
         */
		@Bean
		@ConditionalOnMissingBean
		public RetryLoadBalancerInterceptor loadBalancerRetryInterceptor(
				LoadBalancerClient loadBalancerClient,
				LoadBalancerRetryProperties properties,
				LoadBalancerRequestFactory requestFactory,
				LoadBalancedRetryFactory loadBalancedRetryFactory) {
			return new RetryLoadBalancerInterceptor(loadBalancerClient, properties,
					requestFactory, loadBalancedRetryFactory);
		}

		@Bean
		@ConditionalOnMissingBean
		public RestTemplateCustomizer restTemplateCustomizer(
				final RetryLoadBalancerInterceptor loadBalancerInterceptor) {
			return restTemplate -> {
				List<ClientHttpRequestInterceptor> list = new ArrayList<>(
						restTemplate.getInterceptors());
				list.add(loadBalancerInterceptor);
				restTemplate.setInterceptors(list);
			};
		}

	}

}

    @Configuration
@Conditional(RibbonAutoConfiguration.RibbonClassesConditions.class)
@RibbonClients
@AutoConfigureAfter(
		name = "org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration")
// 声明该配置类在LoadBalancerAutoConfiguration加载之前进行加载
@AutoConfigureBefore({ LoadBalancerAutoConfiguration.class,
		AsyncLoadBalancerAutoConfiguration.class })
@EnableConfigurationProperties({ RibbonEagerLoadProperties.class,
		ServerIntrospectorProperties.class })
@ConditionalOnProperty(value = "spring.cloud.loadbalancer.ribbon.enabled",
		havingValue = "true", matchIfMissing = true)
public class RibbonAutoConfiguration {

	@Autowired(required = false)
	private List<RibbonClientSpecification> configurations = new ArrayList<>();

	@Autowired
	private RibbonEagerLoadProperties ribbonEagerLoadProperties;

	@Bean
	public HasFeatures ribbonFeature() {
		return HasFeatures.namedFeature("Ribbon", Ribbon.class);
	}

    /**
     * 步骤 1
     * 创建SpringClientFactory(Spring客户端工厂)实例, 并注入相关配置
     */
	@Bean
	@ConditionalOnMissingBean
	public SpringClientFactory springClientFactory() {
		SpringClientFactory factory = new SpringClientFactory();
		factory.setConfigurations(this.configurations);
		return factory;
	}

    /**
     * 步骤 3
     * 创建LoadBalancerClient(负载均衡客户端)实例, 并注入SpringClientFactory实例
     * 无意义
     */
	@Bean
	@ConditionalOnMissingBean(LoadBalancerClient.class)
	public LoadBalancerClient loadBalancerClient() {
		return new RibbonLoadBalancerClient(springClientFactory());
	}

    /**
     * 步骤 4
     * 创建LoadBalancedRetryFactory(负载均衡重试工厂)实例, 并注入SpringClientFactory实例
     * 无意义
     */
	@Bean
	@ConditionalOnClass(name = "org.springframework.retry.support.RetryTemplate")
	@ConditionalOnMissingBean
	public LoadBalancedRetryFactory loadBalancedRetryPolicyFactory(
			final SpringClientFactory clientFactory) {
		return new RibbonLoadBalancedRetryFactory(clientFactory);
	}

	@Bean
	@ConditionalOnMissingBean
	public PropertiesFactory propertiesFactory() {
		return new PropertiesFactory();
	}

	@Bean
	@ConditionalOnProperty("ribbon.eager-load.enabled")
	public RibbonApplicationContextInitializer ribbonApplicationContextInitializer() {
		return new RibbonApplicationContextInitializer(springClientFactory(),
				ribbonEagerLoadProperties.getClients());
	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(HttpRequest.class)
	@ConditionalOnRibbonRestClient
	protected static class RibbonClientHttpRequestFactoryConfiguration {

		@Autowired
		private SpringClientFactory springClientFactory;

		@Bean
		public RestTemplateCustomizer restTemplateCustomizer(
				final RibbonClientHttpRequestFactory ribbonClientHttpRequestFactory) {
			return restTemplate -> restTemplate
                    /*
                     * 步骤 8
                     * 对RestTemplate注入RibbonClientHttpRequestFactor实例
                     */
					.setRequestFactory(ribbonClientHttpRequestFactory);
		}

        /**
         * 步骤 2
         * 创建RibbonClientHttpRequestFactory(Ribbon客户端Http请求工厂)实例, 并注入SpringClientFactory实例
         */
		@Bean
		public RibbonClientHttpRequestFactory ribbonClientHttpRequestFactory() {
			return new RibbonClientHttpRequestFactory(this.springClientFactory);
		}

	}

    /**
     * 因OnRibbonRestClientCondition被实例化, 所以导致使用该注解修饰的类将自动装配
     */
	@Target({ ElementType.TYPE, ElementType.METHOD })
	@Retention(RetentionPolicy.RUNTIME)
	@Documented
	@Conditional(OnRibbonRestClientCondition.class)
	@interface ConditionalOnRibbonRestClient {

	}

	private static class OnRibbonRestClientCondition extends AnyNestedCondition {

		OnRibbonRestClientCondition() {
			super(ConfigurationPhase.REGISTER_BEAN);
		}

		@Deprecated // remove in Edgware"
		@ConditionalOnProperty("ribbon.http.client.enabled")
		static class ZuulProperty {

		}

        /**
         * 前置条件
         * 若存在该配置, 则该类将被实例化, 从而导致OnRibbonRestClientCondition也将被实例化
         */
		@ConditionalOnProperty("ribbon.restclient.enabled")
		static class RibbonProperty {

		}

	}

	static class RibbonClassesConditions extends AllNestedConditions {

		//......
        
	}

}
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