关于后端:Zuul源码分析之-网关处理流程

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Zuul 解决流程

一、spring-cloud-starter-zuul starter

  • 咱们先查看 spring-cloud-starter-zuul starter 包下有什么，这里的重点就是 pom.xml 文件，ZuulDeprecationWarningAutoConfiguration.java
  • 关上 org.springframework.cloud/spring-cloud-starter-zuul/pom.xml，能够看到是依赖了 spring-cloud-starter-netflix-zuul
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <parent>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-netflix</artifactId>
  <version>2.2.5.RELEASE</version>
  <relativePath>..</relativePath> <!-- lookup parent from repository -->
 </parent>
 <artifactId>spring-cloud-starter-zuul</artifactId>
 <name>spring-cloud-starter-zuul</name>
 <description>Spring Cloud Starter Zuul (deprecated, please use spring-cloud-starter-netflix-zuul)</description>
 <url>https://projects.spring.io/spring-cloud</url>
 <organization>
  <name>Pivotal Software, Inc.</name>
  <url>https://www.spring.io</url>
 </organization>
 <properties>
  <main.basedir>${basedir}/../..</main.basedir>
 </properties>
 <dependencies>
  <dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
  </dependency>
 </dependencies>
</project>
  • 咱们查看 spring-cloud-starter-netflix-zuul 包
  • 关上 pom.xml 能够看到依赖了 com.netflix.zuul，所以说 Spring Cloud Zuul 是基于 netflix 公司的 zuul 实现的，除此之外还增加了 hystrix 及 ribbon 依赖，所以 zuul 是自带这两个性能的，spring-boot-starter-web 依赖能够使利用成为 web 利用，spring-boot-starter-actuator 是监控依赖 
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix</artifactId>
        <version>2.2.5.RELEASE</version>
    </parent>
    <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
    <name>Spring Cloud Starter Netflix Zuul</name>
    <description>Spring Cloud Starter Netflix Zuul</description>
    <url>https://projects.spring.io/spring-cloud</url>
    <organization>
        <name>Pivotal Software, Inc.</name>
        <url>https://www.spring.io</url>
    </organization>
    <properties>
        <main.basedir>${basedir}/../../..</main.basedir>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-archaius</artifactId>
        </dependency>
        <dependency>
            <groupId>com.netflix.zuul</groupId>
            <artifactId>zuul-core</artifactId>
        </dependency>
    </dependencies>
</project>
  • /META-INF/spring.provides 依赖 spring-platform-netflix-core 模块及 zuul-core 模块
    1 provides: spring-platform-netflix-core, zuul-core
  • 当初咱们进入 spring-platform-netflix-core，看看 Spring 是怎么集成 Netflix 的一系列框架了，上面是代码框架图
  • 能够看到这个 JAR 包也蕴含了 spring.factories 文件，所以 SpringBoot 我的项目启动的时候会检索此配置文件，此文件是 zuul 实现主动注册配置的要害，上面能够看到相熟的 zuul,hystrix,feign,ribbon 的主动配置类 
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.archaius.ArchaiusAutoConfiguration,\
org.springframework.cloud.netflix.feign.ribbon.FeignRibbonClientAutoConfiguration,\
org.springframework.cloud.netflix.feign.FeignAutoConfiguration,\
org.springframework.cloud.netflix.feign.encoding.FeignAcceptGzipEncodingAutoConfiguration,\
org.springframework.cloud.netflix.feign.encoding.FeignContentGzipEncodingAutoConfiguration,\
org.springframework.cloud.netflix.hystrix.HystrixAutoConfiguration,\
org.springframework.cloud.netflix.hystrix.security.HystrixSecurityAutoConfiguration,\
org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration,\
org.springframework.cloud.netflix.rx.RxJavaAutoConfiguration,\
org.springframework.cloud.netflix.metrics.servo.ServoMetricsAutoConfiguration,\
org.springframework.cloud.netflix.zuul.ZuulServerAutoConfiguration,\
org.springframework.cloud.netflix.zuul.ZuulProxyAutoConfiguration

org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker=\
org.springframework.cloud.netflix.hystrix.HystrixCircuitBreakerConfiguration

org.springframework.boot.env.EnvironmentPostProcessor=\
org.springframework.cloud.netflix.metrics.ServoEnvironmentPostProcessor
  • 咱们当初关怀 Zuul 的主动配置类，从下面 spring.factories 文件能够看到和 Zuul 相干的是主动配置了两个类，下图能够看到这两个有继承关系，ZuulProxyAutoConfiguration 性能最为齐全
  • ZuulServerAutoConfiguration 与 ZuulProxyAutoConfiguration
  • ZuulServerAutoConfiguration 主动配置类，启动类上如果有 @EnableZuulServer 则此类失效
    1. 上面代码能够看到大量应用了 @Conditional 作为条件判断，留神这个 ZuulController 这个 Bean，它是 Zuul 的申请入口，这个类实现了 Controller 了，阐明这里也应用了 Spring MVC DispatcherServlet，
    2. 同时此类注册了大量的 ZuulFilter
    3. 代码:
/**
 * @author
 */
@Configuration // 申明是配置类
@EnableConfigurationProperties({ZuulProperties.class}) // 激活 zuul 配置
@ConditionalOnClass(ZuulServlet.class) // 条件 1 存在 ZuulServlet.class
@ConditionalOnBean(ZuulServerMarkerConfiguration.Marker.class) // 条件 2 存在 ZuulServerMarkerConfiguration.Marker.class bean, 即利用应用 @EnableZuulServer 注解
// Make sure to get the ServerProperties from the same place as a normal web app would
@Import(ServerPropertiesAutoConfiguration.class) // 配置 ServerProperties 实例
public class ZuulServerAutoConfiguration {

    @Autowired
    protected ZuulProperties zuulProperties;

    @Autowired
    protected ServerProperties server;

    @Autowired(required = false)
    private ErrorController errorController;

    @Bean
    public HasFeatures zuulFeature() {return HasFeatures.namedFeature("Zuul (Simple)", ZuulServerAutoConfiguration.class);
    }

    @Bean
    @Primary
    public CompositeRouteLocator primaryRouteLocator(Collection<RouteLocator> routeLocators) {return new CompositeRouteLocator(routeLocators);
    }

    @Bean
    @ConditionalOnMissingBean(SimpleRouteLocator.class)
    public SimpleRouteLocator simpleRouteLocator() {return new SimpleRouteLocator(this.server.getServletPrefix(),
                this.zuulProperties);
    }

    /**
     * zuulController, 包装了一个 ZuulServlet 类型的 servlet, 实现对 ZuulServlet 类型的 servlet 的初始化.
     *
     * @return
     */
    @Bean
    public ZuulController zuulController() {return new ZuulController();
    }

    @Bean
    public ZuulHandlerMapping zuulHandlerMapping(RouteLocator routes) {ZuulHandlerMapping mapping = new ZuulHandlerMapping(routes, zuulController());
        mapping.setErrorController(this.errorController);
        return mapping;
    }

    @Bean
    public ApplicationListener<ApplicationEvent> zuulRefreshRoutesListener() {return new ZuulRefreshListener();
    }

    @Bean
    @ConditionalOnMissingBean(name = "zuulServlet")
    public ServletRegistrationBean zuulServlet() {ServletRegistrationBean servlet = new ServletRegistrationBean(new ZuulServlet(),
                this.zuulProperties.getServletPattern());
        // The whole point of exposing this servlet is to provide a route that doesn't
        // buffer requests.
        servlet.addInitParameter("buffer-requests", "false");
        return servlet;
    }

    // pre filters

    @Bean
    public ServletDetectionFilter servletDetectionFilter() {return new ServletDetectionFilter();
    }

    @Bean
    public FormBodyWrapperFilter formBodyWrapperFilter() {return new FormBodyWrapperFilter();
    }

    @Bean
    public DebugFilter debugFilter() {return new DebugFilter();
    }

    @Bean
    public Servlet30WrapperFilter servlet30WrapperFilter() {return new Servlet30WrapperFilter();
    }

    // post filters

    @Bean
    public SendResponseFilter sendResponseFilter() {return new SendResponseFilter();
    }

    @Bean
    public SendErrorFilter sendErrorFilter() {return new SendErrorFilter();
    }

    @Bean
    public SendForwardFilter sendForwardFilter() {return new SendForwardFilter();
    }

    @Bean
    @ConditionalOnProperty(value = "zuul.ribbon.eager-load.enabled", matchIfMissing = false)
    public ZuulRouteApplicationContextInitializer zuulRoutesApplicationContextInitiazer(SpringClientFactory springClientFactory) {
        return new ZuulRouteApplicationContextInitializer(springClientFactory,
                zuulProperties);
    }

    @Configuration
    protected static class ZuulFilterConfiguration {

        @Autowired
        private Map<String, ZuulFilter> filters;

        @Bean
        public ZuulFilterInitializer zuulFilterInitializer(CounterFactory counterFactory, TracerFactory tracerFactory) {FilterLoader filterLoader = FilterLoader.getInstance();
            FilterRegistry filterRegistry = FilterRegistry.instance();
            return new ZuulFilterInitializer(this.filters, counterFactory, tracerFactory, filterLoader, filterRegistry);
        }

    }

    @Configuration
    @ConditionalOnClass(CounterService.class)
    protected static class ZuulCounterFactoryConfiguration {

        @Bean
        @ConditionalOnBean(CounterService.class)
        public CounterFactory counterFactory(CounterService counterService) {return new DefaultCounterFactory(counterService);
        }
    }

    @Configuration
    protected static class ZuulMetricsConfiguration {

        @Bean
        @ConditionalOnMissingBean(CounterFactory.class)
        public CounterFactory counterFactory() {return new EmptyCounterFactory();
        }

        @ConditionalOnMissingBean(TracerFactory.class)
        @Bean
        public TracerFactory tracerFactory() {return new EmptyTracerFactory();
        }

    }

    private static class ZuulRefreshListener
            implements ApplicationListener<ApplicationEvent> {

        @Autowired
        private ZuulHandlerMapping zuulHandlerMapping;

        private HeartbeatMonitor heartbeatMonitor = new HeartbeatMonitor();

        @Override
        public void onApplicationEvent(ApplicationEvent event) {
            if (event instanceof ContextRefreshedEvent
                    || event instanceof RefreshScopeRefreshedEvent
                    || event instanceof RoutesRefreshedEvent) {this.zuulHandlerMapping.setDirty(true);
            }
            else if (event instanceof HeartbeatEvent) {if (this.heartbeatMonitor.update(((HeartbeatEvent) event).getValue())) {this.zuulHandlerMapping.setDirty(true);
                }
            }
        }

    }

}
  • ZuulProxyAutoConfiguration 主动配置类，启动类上如果有对应 @EnableZuulProxy 则此类失效
  • 由下面此类的继承图能够发现这个类继承了 ZuulServerAutoConfiguration，所以此类领有 ZuulServerAutoConfiguration 的所有性能，并在此基础上增加了应用了服务发现作为路由寻址性能
  • 代码：
/**
 * @author
 */
@Configuration // 申明是配置类
@Import({ RibbonCommandFactoryConfiguration.RestClientRibbonConfiguration.class, // 引入 RibbonCommandFactory 配置
        RibbonCommandFactoryConfiguration.OkHttpRibbonConfiguration.class,
        RibbonCommandFactoryConfiguration.HttpClientRibbonConfiguration.class,
        HttpClientConfiguration.class })
@ConditionalOnBean(ZuulProxyMarkerConfiguration.Marker.class) // 条件 2 存在 ZuulProxyMarkerConfiguration.Marker.class bean, 即利用应用 @EnableZuulProxy 注解
public class ZuulProxyAutoConfiguration extends ZuulServerAutoConfiguration {@SuppressWarnings("rawtypes")
    @Autowired(required = false)
    private List<RibbonRequestCustomizer> requestCustomizers = Collections.emptyList();

    /**
     * 网关服务注册实例信息
     */
    @Autowired(required = false)
    private Registration registration;

    /**
     * 服务发现客户端
     */
    @Autowired
    private DiscoveryClient discovery;

    /**
     * serviceId 和路由的映射逻辑
     */
    @Autowired
    private ServiceRouteMapper serviceRouteMapper;

    @Override
    public HasFeatures zuulFeature() {return HasFeatures.namedFeature("Zuul (Discovery)",
                ZuulProxyAutoConfiguration.class);
    }

    /**
     * 动态和动静路由寻址: 动态从配置文件获取, 动静通过服务发现客户端实现. 后者优先级更高
     * @return
     */
    @Bean
    @ConditionalOnMissingBean(DiscoveryClientRouteLocator.class)
    public DiscoveryClientRouteLocator discoveryRouteLocator() {return new DiscoveryClientRouteLocator(this.server.getServletPrefix(),
                this.discovery, this.zuulProperties, this.serviceRouteMapper, this.registration);
    }

    // pre filters
    @Bean
    public PreDecorationFilter preDecorationFilter(RouteLocator routeLocator,
            ProxyRequestHelper proxyRequestHelper) {return new PreDecorationFilter(routeLocator, this.server.getServletPrefix(),
                this.zuulProperties, proxyRequestHelper);
    }

    // route filters
    @Bean
    public RibbonRoutingFilter ribbonRoutingFilter(ProxyRequestHelper helper,
            RibbonCommandFactory<?> ribbonCommandFactory) {
        RibbonRoutingFilter filter = new RibbonRoutingFilter(helper, ribbonCommandFactory,
                this.requestCustomizers);
        return filter;
    }

    @Bean
    @ConditionalOnMissingBean({SimpleHostRoutingFilter.class, CloseableHttpClient.class})
    public SimpleHostRoutingFilter simpleHostRoutingFilter(ProxyRequestHelper helper,
            ZuulProperties zuulProperties,
            ApacheHttpClientConnectionManagerFactory connectionManagerFactory,
            ApacheHttpClientFactory httpClientFactory) {
        return new SimpleHostRoutingFilter(helper, zuulProperties,
                connectionManagerFactory, httpClientFactory);
    }

    @Bean
    @ConditionalOnMissingBean({SimpleHostRoutingFilter.class})
    public SimpleHostRoutingFilter simpleHostRoutingFilter2(ProxyRequestHelper helper,
                                                           ZuulProperties zuulProperties,
                                                           CloseableHttpClient httpClient) {
        return new SimpleHostRoutingFilter(helper, zuulProperties,
                httpClient);
    }

    @Bean
    public ApplicationListener<ApplicationEvent> zuulDiscoveryRefreshRoutesListener() {return new ZuulDiscoveryRefreshListener();
    }

    @Bean
    @ConditionalOnMissingBean(ServiceRouteMapper.class)
    public ServiceRouteMapper serviceRouteMapper() {return new SimpleServiceRouteMapper();
    }

    @Configuration
    @ConditionalOnMissingClass("org.springframework.boot.actuate.endpoint.Endpoint")
    protected static class NoActuatorConfiguration {

        @Bean
        public ProxyRequestHelper proxyRequestHelper(ZuulProperties zuulProperties) {ProxyRequestHelper helper = new ProxyRequestHelper();
            helper.setIgnoredHeaders(zuulProperties.getIgnoredHeaders());
            helper.setTraceRequestBody(zuulProperties.isTraceRequestBody());
            return helper;
        }

    }

    /**
     * 增加 Endpoint
     */
    @Configuration
    @ConditionalOnClass(Endpoint.class)
    protected static class EndpointConfiguration {@Autowired(required = false)
        private TraceRepository traces;

        @ConditionalOnEnabledEndpoint("routes")
        @Bean
        public RoutesEndpoint routesEndpoint(RouteLocator routeLocator) {return new RoutesEndpoint(routeLocator);
        }

        @ConditionalOnEnabledEndpoint("routes")
        @Bean
        public RoutesMvcEndpoint routesMvcEndpoint(RouteLocator routeLocator,
                RoutesEndpoint endpoint) {return new RoutesMvcEndpoint(endpoint, routeLocator);
        }

        @ConditionalOnEnabledEndpoint("filters")
        @Bean
        public FiltersEndpoint filtersEndpoint() {FilterRegistry filterRegistry = FilterRegistry.instance();
            return new FiltersEndpoint(filterRegistry);
        }

        @Bean
        public ProxyRequestHelper proxyRequestHelper(ZuulProperties zuulProperties) {TraceProxyRequestHelper helper = new TraceProxyRequestHelper();
            if (this.traces != null) {helper.setTraces(this.traces);
            }
            helper.setIgnoredHeaders(zuulProperties.getIgnoredHeaders());
            helper.setTraceRequestBody(zuulProperties.isTraceRequestBody());
            return helper;
        }
    }

    private static class ZuulDiscoveryRefreshListener
            implements ApplicationListener<ApplicationEvent> {private HeartbeatMonitor monitor = new HeartbeatMonitor();

        @Autowired
        private ZuulHandlerMapping zuulHandlerMapping;

        @Override
        public void onApplicationEvent(ApplicationEvent event) {if (event instanceof InstanceRegisteredEvent) {reset();
            }
            else if (event instanceof ParentHeartbeatEvent) {ParentHeartbeatEvent e = (ParentHeartbeatEvent) event;
                resetIfNeeded(e.getValue());
            }
            else if (event instanceof HeartbeatEvent) {HeartbeatEvent e = (HeartbeatEvent) event;
                resetIfNeeded(e.getValue());
            }

        }

        private void resetIfNeeded(Object value) {if (this.monitor.update(value)) {reset();
            }
        }

        private void reset() {this.zuulHandlerMapping.setDirty(true);
        }

    }

}
  • ZuulServerAutoConfiguration 与 ZuulProxyAutoConfiguration 具体应用哪种模式，是别离通过 @EnableZuulServer 和 @EnableZuulProxy 注解来区别的
  • 前者应用了 ZuulProperties 进行配置路由寻址;
  • 后者在原来的根底上增加了应用了服务发现作为路由寻址性能, 并应用 Ribbon 做客户端的负载平衡，这个最为罕用

二、@EnableZuulProxy

  • @EnableZuulProxy 注解 
/**
 * Sets up a Zuul server endpoint and installs some reverse proxy filters in it, so it can
 * forward requests to backend servers. The backends can be registered manually through
 * configuration or via DiscoveryClient.
 *
 * @see EnableZuulServer for how to get a Zuul server without any proxying
 *
 * @author
 */
@EnableCircuitBreaker
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(ZuulProxyMarkerConfiguration.class)
public @interface EnableZuulProxy {}
  • @EnableZuulProxy 剖析
  • @EnableCircuitBreaker 注解用于开启短路器性能 
/**
 * Annotation to enable a CircuitBreaker implementation.
 * http://martinfowler.com/bliki/CircuitBreaker.html
 * @author
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import(EnableCircuitBreakerImportSelector.class)
public @interface EnableCircuitBreaker {}
  • @Import(ZuulProxyMarkerConfiguration.class)
  • ZuulProxyMarkerConfiguration.Marker.class
@Configuration
public class ZuulProxyMarkerConfiguration {
    @Bean
    public Marker zuulProxyMarkerBean() {return new Marker();
    }

    class Marker {}}

三、应用 Consul 作为注册核心

  • @EnableZuulProxy 模式下的 zuul 须要注册核心的反对，因为 eureka 曾经被抛弃了，我这里选用的是 Consul

1. 增加 Maven 依赖 

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>

2. 启动类上加上 @EnableDiscoveryClient 注解 

@EnableZuulProxy
@EnableDiscoveryClient
@SpringBootApplication
public class ZuulApplication {public static void main(String[] args) {SpringApplication.run(ZuulApplication.class, args);
    }

}

3. 通过以上所有步骤后，整个服务网关 Zuul 利用就能够发挥作用了

四、总结

1.Spring Cloud 对 Netflix Zuul 做了封装集成, 使得在 Spring Cloud 环境中应用 Zuul 更不便，只需增加 spring-cloud-starter-zuul maven 依赖及启动类上增加 @EnableZuulProxy 就可创立一个 zuul 利用。
2.Spring Cloud Zuul 实际上就是在 Servlet 的根底上增加了一些 ZuulFilter 去实现一些额定事件，封装了就成框架了。

正文完
后端
发表至： 后端
2021-05-25
 0
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