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Spring Cloud Gateway-过滤器工厂详解(GatewayFilter Factories)

TIPS

本文基于 Spring Cloud Greenwich SR2 ,理论支持 Spring Cloud Greenwich SR1 ,其中的新特性标注出来了。

这一节来探讨Spring Cloud Gateway内置的Filter工厂。包括:

1 AddRequestHeader GatewayFilter Factory 2 AddRequestParameter GatewayFilter Factory 3 AddResponseHeader GatewayFilter Factory 4 DedupeResponseHeader GatewayFilter Factory 5 Hystrix GatewayFilter Factory 6 FallbackHeaders GatewayFilter Factory 7 PrefixPath GatewayFilter Factory 8 PreserveHostHeader GatewayFilter Factory 9 RequestRateLimiter GatewayFilter Factory 10 RedirectTo GatewayFilter Factory 11 RemoveHopByHopHeadersFilter GatewayFilter Factory 12 RemoveRequestHeader GatewayFilter Factory 13 RemoveResponseHeader GatewayFilter Factory 14 RewritePath GatewayFilter Factory 15 RewriteResponseHeader GatewayFilter Factory 16 SaveSession GatewayFilter Factory 17 SecureHeaders GatewayFilter Factory 18 SetPath GatewayFilter Factory 19 SetResponseHeader GatewayFilter Factory 20 SetStatus GatewayFilter Factory 21 StripPrefix GatewayFilter Factory 22 Retry GatewayFilter Factory 23 RequestSize GatewayFilter Factory 24 Modify Request Body GatewayFilter Factory 25 Modify Response Body GatewayFilter Factory 26 Default Filters

技巧

  • 断点打在 org.springframework.cloud.gateway.filter.NettyRoutingFilter#filter,就可以调试Gateway转发的具体细节了。

  • 添加如下配置,可观察到一些请求细节:

    yaml
    logging:
      level:
        org.springframework.cloud.gateway: trace
        org.springframework.http.server.reactive: debug
        org.springframework.web.reactive: debug
        reactor.ipc.netty: debug

1 AddRequestHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: add_request_header_route
        uri: https://example.org
        filters:
        - AddRequestHeader=X-Request-Foo, Bar

为原始请求添加名为 X-Request-Foo ,值为 Bar 的请求头。

2 AddRequestParameter GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: add_request_parameter_route
        uri: https://example.org
        filters:
        - AddRequestParameter=foo, bar

为原始请求添加请求参数 foo=bar

3 AddResponseHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: add_response_header_route
        uri: https://example.org
        filters:
        - AddResponseHeader=X-Response-Foo, Bar

添加名为 X-Request-Foo ,值为 Bar 的响应头。

4 DedupeResponseHeader GatewayFilter Factory

TIPS

Spring Cloud Greenwich SR2提供的新特性,低于这个版本无法使用。

强烈建议阅读一下类org.springframework.cloud.gateway.filter.factory.DedupeResponseHeaderGatewayFilterFactory上的注释,比官方文档写得还好。

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: dedupe_response_header_route
        uri: https://example.org
        filters:
        - DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin, RETAIN_FIRST

剔除重复的响应头。

举个例子:

我们在Gateway以及微服务上都设置了CORS(解决跨域)header,如果不做任何配置,请求 -> 网关 -> 微服务,获得的响应就是这样的:

yaml
Access-Control-Allow-Credentials: true, true
Access-Control-Allow-Origin: https://musk.mars, https://musk.mars

也就是Header重复了。要想把这两个Header去重,只需设置成如下即可。

yaml
filters:
- DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin

也就是说,想要去重的Header如果有多个,用空格分隔即可;

去重策略:

yaml
RETAIN_FIRST: 默认值,保留第一个值
RETAIN_LAST: 保留最后一个值
RETAIN_UNIQUE: 保留所有唯一值,以它们第一次出现的顺序保留

5 Hystrix GatewayFilter Factory

TIPS

Hystrix是Spring Cloud第一代中的容错组件,不过已经进入维护模式(相关文章:Spring Cloud Netflix项目进入维护模式之我见 ),未来,Hystrix会被Spring Cloud移除掉,取而代之的是Alibaba Sentinel/Resilience4J

所以本文不做详细探讨了,但Gateway整合Hystrix其实包含了很多姿势。请感兴趣的同学自行前往官方文档了解详情:https://cloud.spring.io/spring-cloud-static/Greenwich.SR2/single/spring-cloud.html#hystrix

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: hystrix_route
        uri: https://example.org
        filters:
        - Hystrix=myCommandName

6 FallbackHeaders GatewayFilter Factory

TIPS

也是对Hystrix的支持,不做详细探讨了,请感兴趣的同学自行前往官方文档了解详情:https://cloud.spring.io/spring-cloud-static/Greenwich.SR2/single/spring-cloud.html#fallback-headers

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: ingredients
        uri: lb://ingredients
        predicates:
        - Path=//ingredients/**
        filters:
        - name: Hystrix
          args:
            name: fetchIngredients
            fallbackUri: forward:/fallback
      - id: ingredients-fallback
        uri: http://localhost:9994
        predicates:
        - Path=/fallback
        filters:
        - name: FallbackHeaders
          args:
            executionExceptionTypeHeaderName: Test-Header

7 PrefixPath GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: prefixpath_route
        uri: https://example.org
        filters:
        - PrefixPath=/mypath

为匹配的路由添加前缀。例如:访问${GATEWAY_URL}/hello 会转发到https://example.org/mypath/hello

8 PreserveHostHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: preserve_host_route
        uri: https://example.org
        filters:
        - PreserveHostHeader

如果不设置,那么名为 Host 的Header由Http Client控制;如果设置了,那么会设置一个请求属性(preserveHostHeader=true),路由过滤器会检查从而去判断是否要发送原始的、名为Host的Header。

9 RequestRateLimiter GatewayFilter Factory

TIPS

在视频Spring Cloud Gateway一章,限流一节会详细讲解。也可阅读官方文档 https://cloud.spring.io/spring-cloud-static/Greenwich.SR2/single/spring-cloud.html#_requestratelimiter_gatewayfilter_factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: requestratelimiter_route
        uri: https://example.org
        filters:
        - name: RequestRateLimiter
          args:
            redis-rate-limiter.replenishRate: 10
            redis-rate-limiter.burstCapacity: 20

10 RedirectTo GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: prefixpath_route
        uri: https://example.org
        filters:
        # 配置成HTTP状态码, URL的形式
        - RedirectTo=302, http://www.itmuch.com
  • HTTP状态码应该是HTTP状态码300序列,例如301
  • URL必须是合法的URL,并且该值会作为名为 Location 的Header。

上面配置表达的意思是: ${GATEWAY_URL}/hello 会重定向到 https://ecme.org/hello ,并且携带一个 Location:http://www.itmuch.com 的Header。

11 RemoveHopByHopHeadersFilter GatewayFilter Factory

yaml
spring.cloud.gateway.filter.remove-hop-by-hop.headers: Connection,Keep-Alive

移除转发请求的Header,多个用 , 分隔。默认情况下,移除如下Header。这些Header是由 IETF 组织规定的。

  • Connection
  • Keep-Alive
  • Proxy-Authenticate
  • Proxy-Authorization
  • TE
  • Trailer
  • Transfer-Encoding
  • Upgrade

12 RemoveRequestHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: removerequestheader_route
        uri: https://example.org
        filters:
        - RemoveRequestHeader=X-Request-Foo

为原始请求删除名为 X-Request-Foo 的请求头。

13 RemoveResponseHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: removeresponseheader_route
        uri: https://example.org
        filters:
        - RemoveResponseHeader=X-Response-Foo

删除名为 X-Request-Foo 的响应头。

14 RewritePath GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: rewritepath_route
        uri: https://example.org
        predicates:
        - Path=/foo/**
        filters:
        # 配置成原始路径正则, 重写后的路径的正则
        - RewritePath=/foo/(?<segment>.*), /$\{segment}

重写请求路径。如上配置,访问 /foo/bar 会将路径改为/bar 再转发,也就是会转发到 https://example.org/bar 。需要注意的是,由于YAML语法,需用$\ 替换 $

15 RewriteResponseHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: rewriteresponseheader_route
        uri: https://example.org
        filters:
        - RewriteResponseHeader=X-Response-Foo, password=[^&]+, password=***

如果名为 X-Response-Foo 的响应头的内容是/42?user=ford&password=omg!what&flag=true,则会被修改为/42?user=ford&password=***&flag=true

16 SaveSession GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: save_session
        uri: https://example.org
        predicates:
        - Path=/foo/**
        filters:
        - SaveSession

在转发到后端微服务请求之前,强制执行 WebSession::save 操作。用在那种像 Spring Session 延迟数据存储(笔者注:数据不是立刻持久化)的,并希望在请求转发前确保session状态保存情况。

如果你将Spring SecutirySpring Session集成使用,并想确保安全信息都传到下游机器,你就需要配置这个filter。

17 SecureHeaders GatewayFilter Factory

添加一系列起安全作用的响应头。Spring Cloud Gateway参考了这篇博客的建议:https://blog.appcanary.com/2017/http-security-headers.html

默认会添加如下Header(包括值):

  • X-Xss-Protection:1; mode=block
  • Strict-Transport-Security:max-age=631138519
  • X-Frame-Options:DENY
  • X-Content-Type-Options:nosniff
  • Referrer-Policy:no-referrer
  • Content-Security-Policy:default-src 'self' https:; font-src 'self' https: data:; img-src 'self' https: data:; object-src 'none'; script-src https:; style-src 'self' https: 'unsafe-inline'
  • X-Download-Options:noopen
  • X-Permitted-Cross-Domain-Policies:none

如果你想修改这些Header的值,可使用如下配置:

前缀:spring.cloud.gateway.filter.secure-headers

上面的header对应的后缀:

  • xss-protection-header
  • strict-transport-security
  • frame-options
  • content-type-options
  • referrer-policy
  • content-security-policy
  • download-options
  • permitted-cross-domain-policies

例如:spring.cloud.gateway.filter.secure-headers.xss-protection-header: 你想要的值

如果想禁用某些Header,可使用如下配置:spring.cloud.gateway.filter.secure-headers.disable ,多个用 , 分隔。例如:spring.cloud.gateway.filter.secure-headers.disable=frame-options,download-options

18 SetPath GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: setpath_route
        uri: https://example.org
        predicates:
        - Path=/foo/{segment}
        filters:
        - SetPath=/{segment}

采用路径template参数,通过请求路径的片段的模板化,来达到操作修改路径的母的,运行多个路径片段模板化。

如上配置,访问${GATEWAY_PATH}/foo/bar ,则对于后端微服务的路径会修改为 /bar

19 SetResponseHeader GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: setresponseheader_route
        uri: http://example.org
        filters:
        - SetResponseHeader=X-Response-Foo, Bar

如果后端服务响应带有名为 X-Response-Foo 的响应头,则将值改为替换成 Bar

20 SetStatus GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: setstatusstring_route
        uri: http://example.org
        filters:
        - SetStatus=BAD_REQUEST
      - id: setstatusint_route
        uri: http://example.org
        filters:
        - SetStatus=401

修改响应的状态码,值可以是数字,也可以是字符串。但一定要是Spring HttpStatus 枚举类中的值。如上配置,两种方式都可以返回HTTP状态码401。

21 StripPrefix GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: nameRoot
        uri: http://nameservice
        predicates:
        - Path=/name/**
        filters:
        - StripPrefix=2

数字表示要截断的路径的数量。如上配置,如果请求的路径为 /name/bar/foo ,则路径会修改为/foo ,也就是会截断2个路径。

22 Retry GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: retry_test
        uri: http://localhost:8080/flakey
        predicates:
        - Host=*.retry.com
        filters:
        - name: Retry
          args:
            retries: 3
            statuses: BAD_GATEWAY

针对不同的响应做重试,可配置如下参数:

  • retries: 重试次数
  • statuses: 需要重试的状态码,取值在 org.springframework.http.HttpStatus
  • methods: 需要重试的请求方法,取值在 org.springframework.http.HttpMethod
  • series: HTTP状态码系列,取值在 org.springframework.http.HttpStatus.Series

23 RequestSize GatewayFilter Factory

yaml
spring:
  cloud:
    gateway:
      routes:
      - id: request_size_route
      uri: http://localhost:8080/upload
      predicates:
      - Path=/upload
      filters:
      - name: RequestSize
        args:
          # 单位字节
          maxSize: 5000000

为后端服务设置收到的最大请求包大小。如果请求大小超过设置的值,则返回 413 Payload Too Large 。默认值是5M

24 Modify Request Body GatewayFilter Factory

TIPS

该过滤器处于 BETA 状态,未来API可能会变化,生产环境请慎用。

可用于在Gateway将请求发送给后端微服务之前,修改请求体内容。该过滤器只能通过代码配置,不支持在配置文件设置。示例:

java
@Bean
public RouteLocator routes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route("rewrite_request_obj", r -> r.host("*.rewriterequestobj.org")
            .filters(f -> f.prefixPath("/httpbin")
                .modifyRequestBody(String.class, Hello.class, MediaType.APPLICATION_JSON_VALUE,
                    (exchange, s) -> return Mono.just(new Hello(s.toUpperCase())))).uri(uri))
        .build();
}

static class Hello {
    String message;

    public Hello() { }

    public Hello(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

25 Modify Response Body GatewayFilter Factory

TIPS

该过滤器处于 BETA 状态,未来API可能会变化,生产环境请慎用。

可用于修改响应体内容。该过滤器只能通过代码配置,不支持在配置文件设置。示例:

java
@Bean
public RouteLocator routes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route("rewrite_response_upper", r -> r.host("*.rewriteresponseupper.org")
            .filters(f -> f.prefixPath("/httpbin")
        		.modifyResponseBody(String.class, String.class,
        		    (exchange, s) -> Mono.just(s.toUpperCase()))).uri(uri)
        .build();
}

26 Default Filters

yaml
spring:
  cloud:
    gateway:
      default-filters:
      - AddResponseHeader=X-Response-Default-Foo, Default-Bar
      - PrefixPath=/httpbin

如果你想为所有路由添加过滤器,可使用该属性。

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