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手写 SpringCloud Gateway，从源码的角度了解它的核心思想以及各个功能的工作原理，从而方便于实现一套属于企业自定义的微服务网关。

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Apache-2.0 license
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它是什么？

前言

  • 本项目旨在手写 SpringCloud Gateway。
  • 参考 SpringCloud Gateway 的核心思想，我基本上用自己的方式实现了它所有的功能。
  • 可以使用它更快的了解 SpringCloud Gateway 的内部工作原理和二次开发。
  • 等等...

特点

  1. 强大的谓词和过滤器，更容易理解和扩展。
  2. 路由信息存储可以动态切换到内存或者redis。
  3. 支持servlet和webflux环境，以及微服务模式和http/https模式。
  4. 支持自定义配置跨域。
  5. 等等...

它是如何工作的？

引入依赖

Servlet环境

Maven

<dependency>
  <groupId>com.lzhpo</groupId>
  <artifactId>panda-gateway-servlet</artifactId>
  <version>${latest-version}</version>
</dependency>

Gradle

implementation 'com.lzhpo:panda-gateway-servlet:${latest-version}'

Webflux环境

Maven

<dependency>
  <groupId>com.lzhpo</groupId>
  <artifactId>panda-gateway-webflux</artifactId>
  <version>${latest-version}</version>
</dependency>

Gradle

implementation 'com.lzhpo:panda-gateway-webflux:${latest-version}'

路由谓词

谓词用来评估当前请求是否符合某个的路由。

名称格式：[PredicateName]RoutePredicateFactory

已存在的谓词

1.Path 路由谓词

例如：如果我想将请求路径是/api/service-sample/**或/api/sample/**转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Path
          args:
            paths: /api/service-sample/**, /api/sample/**

2.Weight 路由谓词

例如：我想给路由分配权重。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      order: 1
      predicates:
        - name: Weight
          args:
            group: service-sample
            weight: 8
    - id: panda-service-sample-02
      uri: lb://panda-service-sample
      order: 2
      predicates:
        - name: Weight
          args:
            group: service-sample
            weight: 2

3.Parameter 路由谓词

例如：如果我想将请求参数含有nickName=Lewis或age=22转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Parameter
          args:
            parameters:
              nickName: Lewis
              age: 20

注意: 值支持正则表达式。

4.ClientIp 路由谓词

例如：如果我想请求客户端IP为192.168.200.111或192.168.200.112转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: ClientIp
          args:
            clientIps: 192.168.200.111, 192.168.200.112

5.Cookie 路由谓词

例如：如果我想让请求cookie含有deviceId=123456或age=22转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Cookie
          args:
            cookies:
              deviceId: 123456
              age: 22

注意: 值支持正则表达式。

6.Header 路由谓词

例如：如果我想让请求cookie含有X-B3-TraceId=123456或X-B3-SpanId=123456转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Header
          args:
            headers:
              X-B3-TraceId: 123456
              X-B3-SpanId: 123456

注意: 值支持正则表达式。

7.Method 路由谓词

例如：如果我想让请求方法是PUT或PATCH转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Method
          args:
            methods: PUT, PATCH

8.After 路由谓词

例如：如果我让请求时间是在2030-06-30T01:29:48.0875598+08:00[Asia/Shanghai]之后的转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: After
          args:
            time: 2030-06-30T01:29:48.0875598+08:00[Asia/Shanghai]

注意: 值的类型是 ZonedDateTime.

你可以很轻松的获取值的格式：

ZonedDateTime.now().format(DateTimeFormatter.ISO_ZONED_DATE_TIME)

9.Before 路由谓词

例如：如果我想让请求时间在2015-06-30T01:29:48.0875598+08:00[Asia/Shanghai]之前的转发到lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Before
          args:
            time: 2015-06-30T01:29:48.0875598+08:00[Asia/Shanghai]

注意: 值的类型是 ZonedDateTime.

你可以很轻松的获取值的格式：

ZonedDateTime.now().format(DateTimeFormatter.ISO_ZONED_DATE_TIME)

10.Between 路由谓词

例如：我想让请求时间在

start time: 2012-06-30T01:29:48.0875598+08:00[Asia/Shanghai]
end time: 2018-06-30T01:29:48.0875598+08:00[Asia/Shanghai]

或者

start time: 2020-10-01T01:29:48.0875598+08:00[Asia/Shanghai]
end time: 2030-10-01T01:29:48.0875598+08:00[Asia/Shanghai]

转发到 lb://panda-service-sample。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: Between
          args:
            times:
              - start: 2012-06-30T01:29:48.0875598+08:00[Asia/Shanghai]
                end: 2018-06-30T01:29:48.0875598+08:00[Asia/Shanghai]
              - start: 2020-10-01T01:29:48.0875598+08:00[Asia/Shanghai]
                end: 2030-10-01T01:29:48.0875598+08:00[Asia/Shanghai]

注意:

  1. 支持多个时间对。

  2. 值的类型是ZonedDateTime.

    你可以很轻松的获取值的格式：

    ZonedDateTime.now().format(DateTimeFormatter.ISO_ZONED_DATE_TIME)

自定义路由谓词关系

您可以自定义定义路由谓词的关系，通过设置gateway.routes[x].metadata.predicate-relation，可以设置为AND（匹配所有谓词）或 OR（匹配任意一个谓词），不区分大小写，默认是AND（匹配所有谓词）。

AND

当请求头中的 X-B3-TraceId为123456，并且请求参数中的nickName为Lewis时使用此路由。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      order: 1
      metadata:
        predicate-relation: and
      predicates:
        - name: Header
          args:
            headers:
              X-B3-TraceId: 123456
        - name: Parameter
          args:
            parameters:
              nickName: Lewis

OR

当请求头中的 X-B3-TraceId为123456，或者请求参数中的nickName为Lewis时使用此路由。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      order: 1
      metadata:
        predicate-relation: or
      predicates:
        - name: Header
          args:
            headers:
              X-B3-TraceId: 123456
        - name: Parameter
          args:
            parameters:
              nickName: Lewis

如何实现一个路由谓词？

我将以After路由谓词为例来告诉你如何实现它。

Servlet环境

@Component
public class AfterRoutePredicateFactory
    extends AbstractRoutePredicateFactory<AfterRoutePredicateFactory.Config> {

  public AfterRoutePredicateFactory() {
    super(Config.class);
  }

  @Override
  public RoutePredicate create(Config config) {
    return request -> {
      ZonedDateTime nowTime = ZonedDateTime.now();
      ZonedDateTime afterTime = config.getTime();
      return nowTime.isAfter(afterTime);
    };
  }

  @Data
  @Validated
  public static class Config {

    @NotNull 
    private ZonedDateTime time;
  }
}

Webflux环境

@Component
public class AfterRoutePredicateFactory
    extends AbstractRoutePredicateFactory<AfterRoutePredicateFactory.Config> {

  public AfterRoutePredicateFactory() {
    super(Config.class);
  }

  @Override
  public RoutePredicate create(Config config) {
    return request -> {
      ZonedDateTime nowTime = ZonedDateTime.now();
      ZonedDateTime afterTime = config.getTime();
      return nowTime.isAfter(afterTime);
    };
  }

  @Data
  @Validated
  public static class Config {

    @NotNull 
    private ZonedDateTime time;
  }
}

使用这个After路由谓词

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      predicates:
        - name: After
          args:
            time: 2030-06-30T01:29:48.0875598+08:00[Asia/Shanghai]

路由过滤器

名称格式：[FilterName]RouteFilterFactory

路由过滤器只应用当前路由。

已存在的路由过滤器

1.AddRequestHeader 路由过滤器

例如：如果您想添加请求标头。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: AddRequestHeader
          args:
            headers:
              name: Lewis
              age: 123

2.AddRequestParameter 路由过滤器

eg：如果你想添加请求参数。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: AddRequestParameter
          args:
            parameters:
              userId: 123

3.AddResponseHeader 路由过滤器

例如：如果你想添加响应头。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: AddResponseHeader
          args:
            headers:
              name: Jack
              age: 20

4.RemoveRequestHeader 路由过滤器

例如：如果您想删除请求标头。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: RemoveRequestHeader
          args:
            headers:
              X-B3-TraceId: 123
              X-B3-SpanId: 456

Notes: the value support regex expression.

5.RemoveRequestParameter 路由过滤器

eg：如果你想删除请求参数。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: RemoveRequestParameter
          args:
            parameters:
              traceId: 123
              spanId: 456

Notes: the value support regex expression.

6.RemoveResponseHeader 路由过滤器

例如：如果你想删除响应头。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: RemoveResponseHeader
          args:
            headers:
              country: China
              city: Guangzhou

Notes: the value support regex expression.

7.RateLimiter 路由过滤器

eg：如果你想限制请求的速率。

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: RateLimiter
          args:
            includeHeaders: true
            replenishRate: 1
            burstCapacity: 1
            requestedTokens: 1
            limitedCode: 429
            limitedMessage: "Request too frequent"
            keyResolver: "#{@clientIpKeyResolver}"
            rateLimiter: "#{@redisRateLimiter}"

如何实现一个路由过滤器？

我将使用AddResponseHeader路由过滤器来告诉你如何实现它。

Servlet环境

@Component
public class AddResponseHeaderRouteFilterFactory
    extends AbstractRouteFilterFactory<AddResponseHeaderRouteFilterFactory.Config>
    implements Ordered {

  public AddResponseHeaderRouteFilterFactory() {
    super(AddResponseHeaderRouteFilterFactory.Config.class);
  }

  @Override
  public RouteFilter create(Config config) {
    return (request, response, chain) -> {
      Map<String, String> configHeaders = config.getHeaders();
      configHeaders.forEach(response::addHeader);
      chain.doFilter(request, response);
    };
  }

  @Data
  @Validated
  public static class Config {

    @NotEmpty 
    private Map<String, String> headers;
  }

  @Override
  public int getOrder() {
    return Ordered.LOWEST_PRECEDENCE;
  }
}

Webflux环境

@Component
public class AddResponseHeaderRouteFilterFactory
    extends AbstractRouteFilterFactory<AddResponseHeaderRouteFilterFactory.Config>
    implements Ordered {

  public AddResponseHeaderRouteFilterFactory() {
    super(Config.class);
  }

  @Override
  public RouteFilter create(Config config) {
    return (exchange, filterChain) -> {
      Map<String, String> configHeaders = config.getHeaders();
      ServerHttpResponse response = exchange.getResponse();
      HttpHeaders respHeaders = response.getHeaders();
      configHeaders.forEach(respHeaders::remove);
      return filterChain.filter(exchange);
    };
  }

  @Data
  @Validated
  public static class Config {

    @NotEmpty 
    private Map<String, String> headers;
  }

  @Override
  public int getOrder() {
    return Ordered.LOWEST_PRECEDENCE;
  }
}

使用这个AddResponseHeader路由过滤器

gateway:
  routes:
    - id: panda-service-sample-01
      uri: lb://panda-service-sample
      filters:
        - name: AddResponseHeader
          args:
            headers:
              name: Jack
              age: 20

全局过滤器

全局过滤器将应用所有路由，并且全局过滤器没有任何名称约束。

如何实现一个全局过滤器？

Servlet环境

@Component
public class ResponseGlobalFilter implements GlobalFilter {

  @Override
  public void filter(
      HttpServletRequest request, HttpServletResponse response, RouteFilterChain chain) {
    response.addHeader("country", "China");
    response.addHeader("city", "Guangzhou");
    chain.doFilter(request, response);
  }
}

Webflux环境

@Component
public class ResponseGlobalFilter implements GlobalFilter {

  @Override
  public Mono<Void> filter(ServerWebExchange exchange, DefaultRouteFilterChain filterChain) {
    ServerHttpResponse response = exchange.getResponse();
    HttpHeaders headers = response.getHeaders();
    headers.add("country", "China");
    headers.add("city", "Guangzhou");
    return filterChain.filter(exchange);
  }
}

跨域配置

例如：如果我想允许所有跨域。

gateway:
  cross-configurations:
    '[/**]':
      allowed-headers: "*"
      allowed-methods: "*"
      allowed-origins: "*"

统一自定义异常响应格式

Servlet环境

方法1-继承DefaultErrorAttributes

import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration;
import org.springframework.boot.web.error.ErrorAttributeOptions;
import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.WebRequest;

/**
 * Customize error response data.
 *
 * @see ErrorMvcAutoConfiguration#errorAttributes()
 * @author lzhpo
 */
@Component
public class GatewayErrorAttributes extends DefaultErrorAttributes {

  @Override
  public Map<String, Object> getErrorAttributes(
      WebRequest webRequest, ErrorAttributeOptions options) {
    Map<String, Object> errors = super.getErrorAttributes(webRequest, options);
    Map<String, Object> errorAttributes = new HashMap<>(4);
    errorAttributes.put("success", false);
    errorAttributes.put("code", errors.getOrDefault("status", 500));
    errorAttributes.put("message", getErrorMessage(errors));
    errorAttributes.put("data", null);
    return errorAttributes;
  }

  /**
   * Get an error message.
   *
   * @param errors error attributes
   * @return error message
   */
  private Object getErrorMessage(Map<String, Object> errors) {
    return Optional.ofNullable(errors.get("message"))
        .orElseGet(() -> errors.getOrDefault("error", "Internal Server Error"));
  }
}

返回格式（例子）：

{
    "code": 504,
    "message": "Gateway Timeout",
    "data": null,
    "success": false
}

Webflux环境

方法1-继承DefaultErrorWebExceptionHandler

import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Collectors;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.boot.autoconfigure.web.WebProperties;
import org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler;
import org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration;
import org.springframework.boot.web.reactive.error.DefaultErrorAttributes;
import org.springframework.boot.web.reactive.error.ErrorAttributes;
import org.springframework.context.ApplicationContext;
import org.springframework.core.annotation.Order;
import org.springframework.http.MediaType;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.reactive.result.view.ViewResolver;
import reactor.core.publisher.Mono;

/**
 * Customize error response.
 *
 * @see DefaultErrorAttributes
 * @see ErrorWebFluxAutoConfiguration#errorWebExceptionHandler
 * @author lzhpo
 */
@Order(-2)
@Component
public class GatewayErrorWebExceptionHandler extends DefaultErrorWebExceptionHandler {

  public GatewayErrorWebExceptionHandler(
      WebProperties webProperties,
      ErrorAttributes errorAttributes,
      ServerProperties serverProperties,
      ApplicationContext applicationContext,
      ObjectProvider<ViewResolver> viewResolvers,
      ServerCodecConfigurer serverCodecConfigurer) {
    super(
        errorAttributes,
        webProperties.getResources(),
        serverProperties.getError(),
        applicationContext);
    setViewResolvers(viewResolvers.orderedStream().collect(Collectors.toList()));
    setMessageWriters(serverCodecConfigurer.getWriters());
    setMessageReaders(serverCodecConfigurer.getReaders());
  }

  @Override
  public Mono<ServerResponse> renderErrorResponse(ServerRequest request) {
    Map<String, Object> errors =
        getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
    int status = (int) errors.getOrDefault("status", 500);

    Map<String, Object> errorAttributes = new HashMap<>(4);
    errorAttributes.put("success", false);
    errorAttributes.put("code", status);
    errorAttributes.put("message", getErrorMessage(errors));
    errorAttributes.put("data", null);

    return ServerResponse.status(status)
        .contentType(MediaType.APPLICATION_JSON)
        .body(BodyInserters.fromValue(errorAttributes));
  }

  /**
   * Get an error message.
   *
   * @param errors error attributes
   * @return error message
   */
  private Object getErrorMessage(Map<String, Object> errors) {
    return Optional.ofNullable(errors.get("message"))
        .orElseGet(() -> errors.getOrDefault("error", "Internal Server Error"));
  }
}

返回格式（例子）：

{
    "code": 504,
    "message": "Gateway Timeout",
    "data": null,
    "success": false
}

方法2-继承DefaultErrorAttributes

使用此方法，webflux环境中自己重写返回的errorAttributes需要有status，否则报空指针异常，servlet环境中没有这种情况发生。

import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler;
import org.springframework.boot.web.error.ErrorAttributeOptions;
import org.springframework.boot.web.reactive.error.DefaultErrorAttributes;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.server.ServerRequest;

/**
 * Customize error response data.
 *
 * @author lzhpo
 */
@Component
public class GatewayErrorAttributes extends DefaultErrorAttributes {

  /**
   * Notes: errorAttributes must containsKey "status", otherwise, will throw NullPointerException
   *
   * <pre>{@code
   * 	protected Mono<ServerResponse> renderErrorResponse(ServerRequest request) {
   * 		Map<String, Object> error = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
   * 		return ServerResponse.status(getHttpStatus(error)).contentType(MediaType.APPLICATION_JSON)
   * 				.body(BodyInserters.fromValue(error));
   *  }
   *
   * 	protected int getHttpStatus(Map<String, Object> errorAttributes) {
   * 		return (int) errorAttributes.get("status");
   *  }
   * }</pre>
   *
   * @see DefaultErrorWebExceptionHandler#renderErrorResponse
   * @see DefaultErrorWebExceptionHandler#getHttpStatus
   * @param request the source request
   * @param options options for error attribute contents
   * @return error attributes
   */
  @Override
  public Map<String, Object> getErrorAttributes(
      ServerRequest request, ErrorAttributeOptions options) {
    Map<String, Object> errors = super.getErrorAttributes(request, options);
    Map<String, Object> errorAttributes = new HashMap<>(4);
    errorAttributes.put("success", false);
    errorAttributes.put("status", errors.getOrDefault("status", 500));
    errorAttributes.put("message", getErrorMessage(errors));
    errorAttributes.put("data", null);
    return errorAttributes;
  }

  /**
   * Get an error message.
   *
   * @param errors error attributes
   * @return error message
   */
  private Object getErrorMessage(Map<String, Object> errors) {
    return Optional.ofNullable(errors.get("message"))
        .orElseGet(() -> errors.getOrDefault("error", "Internal Server Error"));
  }
}

详情可见：

// org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler#renderErrorResponse
protected Mono<ServerResponse> renderErrorResponse(ServerRequest request) {
    Map<String, Object> error = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
    return ServerResponse.status(getHttpStatus(error)).contentType(MediaType.APPLICATION_JSON)
        .body(BodyInserters.fromValue(error));
}

// org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler#getHttpStatus
protected int getHttpStatus(Map<String, Object> errorAttributes) {
    return (int) errorAttributes.get("status");
}

返回格式（例子）：

{
    "status": 504,
    "message": "Gateway Timeout",
    "data": null,
    "success": false
}

Actuator端点API

如果我们想对网关做一些事情，我们需要暴露gateway端点。

management:
  endpoints:
    web:
      exposure:
        include: gateway

1.获取所有路由配置

GET /actuator/gateway/routes

2.根据路由ID获取路由配置

GET /actuator/gateway/routes/${routeId}

3.获取所有路由谓词类名

GET /actuator/gateway/routes/predicates

4.根据路由ID获取路由谓词类名

GET /actuator/gateway/routes/${routeId}/predicates

5.获取所有路由过滤器类名

GET /actuator/gateway/routes/filters

6.根据路由ID获取路由过滤器类名

GET /actuator/gateway/routes/${routeId}/filters

7.获取所有全局过滤器类名

GET /actuator/gateway/routes/global-filters

8.刷新路由

POST /actuator/gateway/routes/refresh

About

手写 SpringCloud Gateway，从源码的角度了解它的核心思想以及各个功能的工作原理，从而方便于实现一套属于企业自定义的微服务网关。

Topics

microservices spring-boot gateway spring-cloud-gateway

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Releases 2

1.0.1 Latest
Jul 18, 2022
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