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Spring Cloud

Eureka - 注册中心

  • 显示已注册的服务：http://localhost:7000/
  • 监控信息：http://localhost:7000/actuator
  • Eureka REST operations - 官网 - 请求Eureka Server URL地址时需去掉/v2/
    • 返回所有Apps的信息 - http://localhost:7000/eureka/apps
    • 返回指定应用的所有实例信息 - http://localhost:7000/eureka/apps/{svcId}

Standalone Mode

spring:
  application:
    name: eureka-server
server:
  port: 7000
eureka:
  client:
    fetch-registry: false
    register-with-eureka: false

Peer Awareness

  • 例1

    spring:
  application:
    name: eureka-server
management:
  endpoints:
    web:
      exposure:
        # 测试使用 - 开放所有端口
        include: "*"
eureka:
  client:
    serviceUrl:
      defaultZone: http://peer1:7000/eureka/,http://peer2:7001/eureka/,http://peer3:7002/eureka/

---
spring:
  profiles: peer1
server:
  port: 7000
eureka:
  instance:
    hostname: peer1

---
spring:
  profiles: peer2
server:
  port: 7001
eureka:
  instance:
    hostname: peer2

---
spring:
  profiles: peer3
server:
  port: 7002
eureka:
  instance:
    hostname: peer3

    127.0.0.1 peer1
127.0.0.1 peer2
127.0.0.1 peer3

  • 例2

    spring:
  application:
    name: eureka-server
server:
  port: 7000
management:
  endpoints:
    web:
      exposure:
        # 测试使用 - 开放所有端口
        include: "*"
eureka:
  client:
    serviceUrl:
      defaultZone: http://192.168.100.101:7000/eureka/,http://192.168.100.102:7000/eureka/,http://192.168.100.103:7000/eureka/
  instance:
    # 使用IP
    prefer-ip-address: true

注：Peer Awareness模式不一定非得3个实例，2个或大于3个都可以。

Hystrix - 熔断机制

  • Feign启用Hystrix时，HystrixCommandKey默认通过以下规则生成：feign.Feign.configKey(java.lang.Class, java.lang.reflect.Method)

    hystrix:
  command:
    # 通过上述Feign.configKey()方法生成
    FooHttpApi#list(String,List):
      execution.isolation.thread.timeoutInMilliseconds: 10000
    • HystrixPropertiesStrategy - 属性获取规则
    • HystrixCommandProperties - HystrixCommand配置及默认值
    • HystrixThreadPoolProperties - HystrixThreadPool配置及默认值
    • 默认HystrixThreadPoolKey值为HystrixCommandGroupKey，HystrixCommandGroupKey为Feign Client Name

  • hystrix-javanica -【java注解风格 - 重要】

  • How it Works

  • How To Use

  • 监控详解及配置调优(timeouts/threads/semaphores)

  • Configuration

  • Metrics and Monitoring

  • Plugins

  • Propagating the Security Context or Using Spring Scopes

  • SEMAPHORE和THREAD区别

    • THREAD超时后可立即放弃线程执行，SEMAPHORE超时后也需要等待Command执行完毕后才能执行后续逻辑（即使配了fallback）， 因为SEMAPHORE使用caller线程执行的，并没有另起线程。所以SEMAPHORE通常使用于执行时间不长的场景中。 if a dependency is isolated with a semaphore and then becomes latent, the parent threads will remain blocked until the underlying network calls timeout.

  • Making the Netflix API More Resilient - Hystrix概念及监控介绍

  • Fault Tolerance in a High Volume, Distributed System - 深入讲解Fault Tolerance、原理图、最佳实践

  • Performance and Fault Tolerance for the Netflix API -【非常重要】 - Fault Tolerance详解、性能调优、提供各种指标依据（包含SEMAPHORE和THREAD压测对比数据）、指标详解

    • Tryable semaphores for “trusted” clients and fallbacks. Semaphore isolation on the other hand is used for dependencies which are very high-volume in-memory lookups that never result in a synchronous network request.
    • Separate threads for “untrusted” clients
    • Thread Queue
      • Requests in queue block user threads thus must be considered part of the resources being allocated to a dependency.
      • Setting a queue to 100 is equivalent to saying 100 incoming requests can block while waiting for this dependency. There is typically not a good reason for having a queue size higher than 5-10.
      • Bursting should be handled through batching and throughput should be accommodated by a large enough thread pool. It is better to increase the thread-pool size rather than the queue as commands executing in the thread-pool receive forward progress whereas items in the queue do not.

Hystrix Dashboard

访问地址：http://{localhost}:{port}/hystrix

Turbine

Turbine is a tool for aggregating streams of Server-Sent Event (SSE) JSON data into a single stream. The targeted use case is metrics streams from instances in an SOA being aggregated for dashboards.

  • spring-cloud-netflix-hystrix - 官网

    • 显示当前可用的clusters - http://localhost:7300/clusters

  • Getting Started (1.x)

  • Configuration (1.x)

  • 配置1 - 手动配置cluster-config、app-config（一对一）

    turbine:
  aggregator:
    cluster-config: EASYCODE-DEMO-ORG
  app-config: easycode-demo-org

    TurbineClustersProvider默认使用ConfigurationBasedTurbineClustersProvider，此类只会去获取cluster-config 配置项。如果你没有配置cluster-config配置项，则获取不到cluster，也就没有监控的应用可显示。

    InstanceDiscovery默认使用EurekaInstanceDiscovery，此类会根据app-config配置项，去eureka注册中心获取应用对应的所有实例。 实例取出来后，默认使用com.netflix.appinfo.InstanceInfo的appName属性作为cluster值。当监控页面需要查看特定cluster 信息时，首先会去TurbineClustersProvider查看有没有此值，有则再过滤出InstanceDiscovery实例中cluster值相等的应用实例。

  • 配置2 - 自动配置

    /**
 * 通过{@link EurekaClient}自动获取当前所有的应用，并把应用名（大写）作为Cluster值
 *
 * @param eurekaClient EurekaClient
 * @return {@link TurbineClustersProvider}
 */
@Bean
public TurbineClustersProvider clustersProvider(EurekaClient eurekaClient) {
    return new EurekaBasedTurbineClustersProvider(eurekaClient);
}

@Bean
public InstanceDiscovery instanceDiscovery(TurbineProperties turbineProperties, EurekaClient eurekaClient,
    TurbineClustersProvider clustersProvider) {
    return new EurekaInstanceDiscovery(turbineProperties, eurekaClient) {
        /**
         * 重写获取应用名的来源，例如从Eureka获取
         */
        @Override
        protected List<String> getApplications() {
            return clustersProvider.getClusterNames();
        }
    };
}

    注：上述只是例子，需要自行调整（例：通过Eureka返回的数据信息，来判断此应用能否适用于监控）。 通过上述的例子，就不需要手动配置cluster-config/app-config。

  • 配置3 - 混合配置cluster-config、app-config

    turbine:
  aggregator:
    cluster-config: SYSTEM,USER
  app-config: easycode-demo-org,easycode-demo-shop,easycode-demo-user
  clusterNameExpression: metadata['cluster']

    即从Eureka服务中或取easycode-demo-org/easycode-demo-shop/easycode-demo-user三个应用的信息，获取 metadata.cluster(配置于eureka.instance.metadata-map)属性值，与cluster-config配置中的值进行匹配，匹配成功则表明该应用属于对应的cluster。

    注：参考官方文档

Archaius - 动态更新配置

Ribbon - 客户端负载均衡，适用于HTTP、TCP

  • Native
  • Spring Cloud

    • 官网 - 【重要】

    • IClientConfig默认实现为DefaultClientConfigImpl（参考RibbonClientConfiguration类），此类里面提供了Ribbon Client的默认配置

    • Using the Ribbon API Directly

      public class MyClass {
    @Autowired
    private LoadBalancerClient loadBalancer;

    public void doStuff() {
        ServiceInstance instance = loadBalancer.choose("stores");
        URI storesUri = URI.create(String.format("http://%s:%s", instance.getHost(), instance.getPort()));
        // ... do something with the URI
    }
}
      @Configuration
public class MyConfiguration {

    @Bean
    @LoadBalanced
    RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

public class MyClass {
    @Autowired
    private RestTemplate restTemplate;

    public String doOtherStuff() {
        return restTemplate.getForObject("http://stores/stores", String.class);
    }
}

    • Ribbon是否会重试依赖于AbstractLoadBalancerAwareClient.getRequestSpecificRetryHandler()实现及是否使用了Spring-retry。 OpenFeign配置的Retryer（FeignClientsConfiguration）和Ribbon的重试没有任何关联，两个是完全独立的。

    • Retrying Failed Requests - 【重要】

注：当获取到的服务使用了域名时，当http连接超时设置为1s时，不是指整个操作连接超时为1s，而是域名解析出的所有IP 连接超时都是1s。所以会出现一种现象：当一个域名解析到4个IP时，且请求的connectTimeout、readTimeout都配置为1s， 当这4个IP都不通时，整个请求耗时会是4s。因为尝试了4个IP的连接，且4个IP都连接超时。

OpenFeign - 简化java http client编程

注：非常重要的组件，此组件的关注程度高于Ribbon和Hystrix。

Zuul - Router and Filter

Zuul是由Netflix提供的基于JVM路由及服务端负载均衡的组件。Zuul是一个网关服务，提供了dynamic routing、monitoring、 resiliency、security等功能。

总结

  • 当Spring Cloud Zuul启用从注册中心获取服务时，获取到的服务在创建ZuulRoute对象时，不会设置sensitiveHeaders属性， 此时PreDecorationFilter会获取默认的zuul.sensitive-headers（默认值为："Cookie", "Set-Cookie", "Authorization"）。 所以此时如果你集成了Spring OAuth2，并不会把OAuth2 Access Token传递给下游服务，因为Authorization被忽略了。

    解决方案如下，去除Authorization配置项：

    zuul:
  # 默认值为："Cookie", "Set-Cookie", "Authorization"
  sensitive-headers: "Cookie, Set-Cookie"
proxy:
  auth:
    routes:
      server1: oauth2
      server2: passthru
      server3: none

    注：此时可以通过proxy.auth.routes来配置具体哪个服务需要使用Authorization header，哪些直接剔除掉。

    • oauth2 - authorization header值重置为当前OAuth2 Token，传递给下游服务
    • passthru - 当前请求有authorization header则传递给下游服务，没有也不会去创建
    • none - 忽略authorization header，不会传递给下游服务

  • 自定义特定服务的 route sensitiveHeaders，优先级高于sensitiveHeaders配置

    zuul:
  routes:
    users:
      path: /myusers/**
      # 全局sensitiveHeaders配置项无效
      sensitiveHeaders: Cookie,Set-Cookie,Authorization
      url: https://downstream
    zuul:
  routes:
    users:
      path: /myusers/**
      # 全局sensitiveHeaders配置项无效
      sensitiveHeaders:
      url: https://downstream

  • ignore-security-headers: true - 忽略SpringSecurity安全相关的header，去除downstream response中SpringSecurity安全相关的header。 但你可能会发现浏览器中response还有SpringSecurity安全相关的header，这是由于网关服务自己SpringSecurity后面添加的。

Spring Cloud Config

Spring Cloud Gateway

  • Retrieving route filters

    • GET /actuator/gateway/globalfilters - 返回全局filter
    • GET /actuator/gateway/routefilters - 返回GatewayFilter factories
    • POST /actuator/gateway/refresh - To clear the routes cache
    • GET /actuator/gateway/routes - 返回定义的GatewayFilter
    • GET /actuator/gateway/routes/{id} - 返回指定route的详细信息
    • POST /gateway/routes/{id_route_to_create} - 创建route，请求体为GET /actuator/gateway/routes/{id}JSON格式
    • DELETE /gateway/routes/{id_route_to_delete} - 删除route

  • 输出Reactor Netty Access Logs - 【重要】

    开启Reactor Netty Access Logs的配置项：-Dreactor.netty.http.server.accessLogEnabled=true，必须使用Java System Property 而不是Spring Boot property。开启后可以把日志分离出单个日志文件（可选），例：

    <appender name="accessLog" class="ch.qos.logback.core.FileAppender">
    <file>access_log.log</file>
    <encoder>
        <pattern>%msg%n</pattern>
    </encoder>
</appender>
<appender name="async" class="ch.qos.logback.classic.AsyncAppender">
    <appender-ref ref="accessLog" />
</appender>

<logger name="reactor.netty.http.server.AccessLog" level="INFO" additivity="false">
    <appender-ref ref="async"/>
</logger>

  • 参考文档

注：当前Spring Cloud Gateway版本（Greenwich.RELEASE）不支持Ribbon的LoadBalancerRules、retriesNextServer、 隔离无效node等功能，只用到了Ribbon的choose server功能，如果想使用上述功能请切换至Spring Cloud Zuul

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