Zuul processing process

A, spring – the cloud – starter – zuul starter

We check the spring – the cloud – starter – zuul starter what’s under the package, the key here is pom. The XML file, ZuulDeprecationWarningAutoConfiguration. Java
Open the org. Springframework. Cloud/spring — cloud – starter – zuul/pom. XML, you can see is dependent on the spring – the cloud – starter – netflix – zuul

<? The 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" > The < modelVersion > 4.0.0 < / modelVersion > < the 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>

Let’s look at the spring-cloud-starter- Netflix-Zuul package
If you open pom. XML, you can see that it relies on com.netflix. Zuul, so Spring Cloud Zuul is based on Netflix Zuul, and it also adds hystrix and ribbon dependencies. Spring-boot-starter – Web dependency enables an application to become a Web application, and spring-boot-starter-actuator is a monitoring dependency

The < 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" > The < modelVersion > 4.0.0 < / modelVersion > < the parent > < groupId > org. Springframework. Cloud < / groupId > < artifactId > spring - the 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 depends on the spring-platform-Netflix-core module and zuul-core module

1 provides: spring-platform-netflix-core, zuul-core
Now let’s go to Spring-Platform-Netflix-Core and see how Spring integrates with Netflix’s framework
You can see that this JAR also contains the spring.factories file, so the SpringBoot project retries this configuration file when it starts. This file is the key to zuul’s automatic registration configuration. You can see below familiar zuul, hystrix, feign, automatic configuration of ribbon class

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

We are now concerned about Zuul automatic configuration classes, from the spring. The above factories related files can be seen and Zuul is automatically configured for two classes, below you can see the two have inheritance relationship, ZuulProxyAutoConfiguration function most completely
ZuulServerAutoConfiguration and ZuulProxyAutoConfiguration
ZuulServerAutoConfiguration automatic configuration, start if there are @ EnableZuulServer such effect on 1. Note that this ZuulController Bean, which is Zuul’s entry to the request, implements Controller. Note that Spring MVC DispatcherServlet is also used here, 2. At the same time this class registers a large number of ZuulFilter.

/ * * * @ author * / @ Configuration / / statement is to configure the @ EnableConfigurationProperties ({ZuulProperties. Class}) / / activate zuul Configuration ConditionalOnClass(zuulservlet.class) // Condition 1 has Zuulservlet.class @ ConditionalOnBean ZuulServerMarkerConfiguration. Marker. (class) / 2 / conditions exist ZuulServerMarkerConfiguration Marker. The class bean, Make sure to get the ServerProperties from the same place as a normal Web app would @ Import (ServerPropertiesAutoConfiguration. Class) / / configure ServerProperties instance 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, which wraps a servlet of type ZuulServlet, * * @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 automatic configuration, start on if there are corresponding @ EnableZuulProxy such effect
By the above such inheritance diagrams can find this class inherits ZuulServerAutoConfiguration, so it has ZuulServerAutoConfiguration all functions, and based on this added using the function of service discovery as routing addressing
Code:

/**
 * @author
 */
@Configuration // 声明是配置类
@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, 即应用使用@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);
    }

    /**
     * 静态和动态路由寻址: 静态从配置文件获取, 动态通过服务发现客户端完成. 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;
        }

    }

    /**
     * 添加 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 and ZuulProxyAutoConfiguration which model to use, it is respectively by @ EnableZuulServer and @ EnableZuulProxy annotations to the difference
The former uses ZuulProperties for configured routing addressing;
The latter adds the use of service discovery as routing addressing and the Ribbon for client load balancing, the most commonly used

Second, @ EnableZuulProxy

@ EnableZuulProxy annotations

/**
 * 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 analysis
The @enablecircuitbreaker annotation is used to enable the short-circuit function

/**
 * 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 {
    }
}

Use Consul as the registry

@enablezuulProxy mode zuul requires registry support because Eureka has been abandoned, I choose Consul here

1. Add Maven dependencies

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

2. Add the @enableDiscoveryClient annotation to the startup class

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

3. After all the steps above, the entire service gateway Zuul application is ready to work

Four,

1.Spring Cloud encapsulates and integrates Netflix Zuul, making it more convenient to use Zuul in Spring Cloud environment. Just add the spring-cloud-starter- Zuul Maven dependencies and add @enablezuulProxy to the startup class to create a Zuul application. 2.Spring Cloud Zuul actually adds some ZuulFilter on the basis of servlets to do some extra things, which is wrapped into a framework.

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Zuul source analysis of the gateway process

Zuul processing process

A, spring – the cloud – starter – zuul starter

Second, @ EnableZuulProxy

Use Consul as the registry

1. Add Maven dependencies

2. Add the @enableDiscoveryClient annotation to the startup class

3. After all the steps above, the entire service gateway Zuul application is ready to work

Four,

Zuul source analysis of the gateway process

Zuul processing process

A, spring – the cloud – starter – zuul starter

Second, @ EnableZuulProxy

Use Consul as the registry

1. Add Maven dependencies

2. Add the @enableDiscoveryClient annotation to the startup class

3. After all the steps above, the entire service gateway Zuul application is ready to work

Four,

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