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1 簡介
見名知義，Spring Cloud Gateway是用於微服務場景的網關組件，它是基於Spring WebFlux，也就是Reactive的。從實現原理上，它的性能應該是比Zuul會更好。
它的工作原理如下圖所示：
簡單而言就是通過一連串的Filter處理匹配到特定規則Predicates的請求。所以最主要就是做了兩件事：
（1）哪些請求可以被它處理，由Predicates決定；
（2）如何處理，由Filters決定。
2 路由條件判斷Predicates
2.1 時間匹配After
表示在什么時間之后才算滿足條件匹配路由：
spring:
cloud:
gateway:
routes:
- id: after_route
uri: https://example.org
predicates:
- After=2020-01-20T17:42:47.789-07:00[America/Denver]
2.2 時間匹配Before
表示在什么時間之前匹配路由：
spring:
cloud:
gateway:
routes:
- id: before_route
uri: https://example.org
predicates:
- Before=2017-01-20T17:42:47.789-07:00[America/Denver]
2.3 時間段匹配Between
表示在什么時間段匹配路由：
spring:
cloud:
gateway:
routes:
- id: between_route
uri: https://example.org
predicates:
- Between=2017-01-20T17:42:47.789-07:00[America/Denver], 2017-01-21T17:42:47.789-07:00[America/Denver]
2.4 Cookie匹配
表示通過判斷Cookie的鍵值來匹配路由，其中值支持正則表達式：
spring:
cloud:
gateway:
routes:
- id: cookie_route
uri: https://example.org
predicates:
- Cookie=chocolate, ch.p
2.5 請求頭匹配Header
表示通過判斷Http請求的Header來匹配路由：
spring:
cloud:
gateway:
routes:
- id: header_route
uri: https://example.org
predicates:
- Header=X-Request-Id, \d+
2.6 主機名匹配Host
通過判斷Hostname來匹配路由：
spring:
cloud:
gateway:
routes:
- id: host_route
uri: https://example.org
predicates:
- Host=**.somehost.org,**.anotherhost.org
2.7 請求方法匹配Method
表示通過判斷請求方法來匹配路由：
spring:
cloud:
gateway:
routes:
- id: method_route
uri: https://example.org
predicates:
- Method=GET,POST
2.8 請求路徑匹配Path
表示通過判斷請求路徑來匹配路由，很常用：
spring:
cloud:
gateway:
routes:
- id: path_route
uri: https://example.org
predicates:
- Path=/red/{segment},/blue/{segment}
2.9 請求參數匹配Query
表示通過判斷請求參數來匹配路由：
spring:
cloud:
gateway:
routes:
- id: query_route
uri: https://example.org
predicates:
- Query=red, gree.
2.10 IP地址匹配RemoteAddr
表示通過判斷IP地址來匹配路由：
spring:
cloud:
gateway:
routes:
- id: remoteaddr_route
uri: https://example.org
predicates:
- RemoteAddr=192.168.1.1/24
2.11 權重匹配Weight
通過權重來匹配路由：
spring:
cloud:
gateway:
routes:
- id: weight_high
uri: https://weighthigh.org
predicates:
- Weight=group1, 8
- id: weight_low
uri: https://weightlow.org
predicates:
- Weight=group1, 2
3 功能強大的GatewayFilter
Spring提供許多強大的GatewayFilter對請求進行處理。
3.1 添加請求頭
給請求添加Header：
spring:
cloud:
gateway:
routes:
- id: add_request_header_route
uri: https://example.org
predicates:
- Path=/red/{segment}
filters:
- AddRequestHeader=X-Request-Red, Blue-{segment}
3.2 添加請求參數
spring:
cloud:
gateway:
routes:
- id: add_request_parameter_route
uri: https://example.org
predicates:
- Host: {segment}.myhost.org
filters:
- AddRequestParameter=foo, bar-{segment}
3.3 添加返回Header
spring:
cloud:
gateway:
routes:
- id: add_response_header_route
uri: https://example.org
predicates:
- Host: {segment}.myhost.org
filters:
- AddResponseHeader=foo, bar-{segment}
3.4 刪除重復返回Header
spring:
cloud:
gateway:
routes:
- id: dedupe_response_header_route
uri: https://example.org
filters:
- DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin
3.5 斷路器Hystrix
簡單配置：
spring:
cloud:
gateway:
routes:
- id: hystrix_route
uri: https://example.org
filters:
- Hystrix=myCommandName
較復雜配置：
spring:
cloud:
gateway:
routes:
- id: hystrix_route
uri: lb://backing-service:8088
predicates:
- Path=/consumingserviceendpoint
filters:
- name: Hystrix
args:
name: fallbackcmd
fallbackUri: forward:/incaseoffailureusethis
- RewritePath=/consumingserviceendpoint, /backingserviceendpoint
3.6 斷路器CircuitBreaker
簡單配置：
spring:
cloud:
gateway:
routes:
- id: circuitbreaker_route
uri: https://example.org
filters:
- CircuitBreaker=myCircuitBreaker
較復雜配置：
spring:
cloud:
gateway:
routes:
- id: circuitbreaker_route
uri: lb://backing-service:8088
predicates:
- Path=/consumingServiceEndpoint
filters:
- name: CircuitBreaker
args:
name: myCircuitBreaker
fallbackUri: forward:/inCaseOfFailureUseThis
- RewritePath=/consumingServiceEndpoint, /backingServiceEndpoint
3. 7 請求頭改名
spring:
cloud:
gateway:
routes:
- id: map_request_header_route
uri: https://example.org
filters:
- MapRequestHeader=Blue, X-Request-Red
3.8 路徑添加前綴
這個要注意和匹配路徑區分，它是在匹配后再加個前綴：
spring:
cloud:
gateway:
routes:
- id: prefixpath_route
uri: https://example.org
filters:
- PrefixPath=/mypath
請求/hello變成/mypath/hello。
3.9 重定向
spring:
cloud:
gateway:
routes:
- id: prefixpath_route
uri: https://example.org
filters:
- RedirectTo=302, https://acme.org
3.10 刪除請求頭
spring:
cloud:
gateway:
routes:
- id: removerequestheader_route
uri: https://example.org
filters:
- RemoveRequestHeader=X-Request-Foo
3.11 刪除返回頭
spring:
cloud:
gateway:
routes:
- id: removeresponseheader_route
uri: https://example.org
filters:
- RemoveResponseHeader=X-Response-Foo
3.12 刪除請求參數
spring:
cloud:
gateway:
routes:
- id: removerequestparameter_route
uri: https://example.org
filters:
- RemoveRequestParameter=red
3.13 重寫路徑
spring:
cloud:
gateway:
routes:
- id: rewritepath_route
uri: https://example.org
predicates:
- Path=/red/**
filters:
- RewritePath=/red(?<segment>/?.*), $\{segment}
3.14 設置路徑
spring:
cloud:
gateway:
routes:
- id: setpath_route
uri: https://example.org
predicates:
- Path=/red/{segment}
filters:
- SetPath=/{segment}
3.15 設置請求頭
spring:
cloud:
gateway:
routes:
- id: setrequestheader_route
uri: https://example.org
predicates:
- Host: {segment}.myhost.org
filters:
- SetRequestHeader=foo, bar-{segment}
3.16 設置返回頭
spring:
cloud:
gateway:
routes:
- id: setresponseheader_route
uri: https://example.org
predicates:
- Host: {segment}.myhost.org
filters:
- SetResponseHeader=foo, bar-{segment}
3.17 設置返回狀態碼
spring:
cloud:
gateway:
routes:
- id: setstatusstring_route
uri: https://example.org
filters:
- SetStatus=BAD_REQUEST
- id: setstatusint_route
uri: https://example.org
filters:
- SetStatus=401
3.18 去掉路徑前綴
spring:
cloud:
gateway:
routes:
- id: nameRoot
uri: https://nameservice
predicates:
- Path=/name/**
filters:
- StripPrefix=2
這配置請求/name/blue/red，實際就是請求nameservice的/red，去掉兩個前綴。
3.19 重試Retry GatewayFilter
想不到居然還有強大的重試功能：
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
methods: GET,POST
backoff:
firstBackoff: 10ms
maxBackoff: 50ms
factor: 2
basedOnPreviousValue: false
3.20 請求大小限制
spring:
cloud:
gateway:
routes:
- id: request_size_route
uri: http://localhost:8080/upload
predicates:
- Path=/upload
filters:
- name: RequestSize
args:
maxSize: 5000000
3.21 默認Filter
如果希望對所有路由都生效，可以添加默認Filter：
spring:
cloud:
gateway:
default-filters:
- AddResponseHeader=X-Response-Default-Red, Default-Blue
- PrefixPath=/httpbin
4 全局Global Filters
全局過濾器GlobalFilter接口和GatewayFilter的方法是一樣的，但它是用於所有路由的。當請求過來時，整個Filter Chain是包含了所有的GlobalFilters和匹配上的GatewayFilters，執行順序由getOrder()方法決定。
如下：
@Bean
public GlobalFilter customFilter() {
return new CustomGlobalFilter();
}
public class CustomGlobalFilter implements GlobalFilter, Ordered {
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
log.info("custom global filter");
return chain.filter(exchange);
}
@Override
public int getOrder() {
return -1;
}
}
5 一切皆可自定義
Spring支持開發人員自定義Predicate、GatewayFilter和GlobalFilter。
5.1 自定義Predicate
public class MyRoutePredicateFactory extends AbstractRoutePredicateFactory<HeaderRoutePredicateFactory.Config> {
public MyRoutePredicateFactory() {
super(Config.class);
}
@Override
public Predicate<ServerWebExchange> apply(Config config) {
// grab configuration from Config object
return exchange -> {
//grab the request
ServerHttpRequest request = exchange.getRequest();
//take information from the request to see if it
//matches configuration.
return matches(config, request);
};
}
public static class Config {
//Put the configuration properties for your filter here
}
}
5.2 自定義GatewayFilter
Pre的過濾器：
public class PreGatewayFilterFactory extends AbstractGatewayFilterFactory<PreGatewayFilterFactory.Config> {
public PreGatewayFilterFactory() {
super(Config.class);
}
@Override
public GatewayFilter apply(Config config) {
// grab configuration from Config object
return (exchange, chain) -> {
//If you want to build a "pre" filter you need to manipulate the
//request before calling chain.filter
ServerHttpRequest.Builder builder = exchange.getRequest().mutate();
//use builder to manipulate the request
return chain.filter(exchange.mutate().request(builder.build()).build());
};
}
public static class Config {
//Put the configuration properties for your filter here
}
}
Post的過濾器：
public class PostGatewayFilterFactory extends AbstractGatewayFilterFactory<PostGatewayFilterFactory.Config> {
public PostGatewayFilterFactory() {
super(Config.class);
}
@Override
public GatewayFilter apply(Config config) {
// grab configuration from Config object
return (exchange, chain) -> {
return chain.filter(exchange).then(Mono.fromRunnable(() -> {
ServerHttpResponse response = exchange.getResponse();
//Manipulate the response in some way
}));
};
}
public static class Config {
//Put the configuration properties for your filter here
}
}
5.3 自定義GlobalFilter
@Bean
public GlobalFilter customGlobalFilter() {
return (exchange, chain) -> exchange.getPrincipal()
.map(Principal::getName)
.defaultIfEmpty("Default User")
.map(userName -> {
//adds header to proxied request
exchange.getRequest().mutate().header("CUSTOM-REQUEST-HEADER", userName).build();
return exchange;
})
.flatMap(chain::filter);
}
@Bean
public GlobalFilter customGlobalPostFilter() {
return (exchange, chain) -> chain.filter(exchange)
.then(Mono.just(exchange))
.map(serverWebExchange -> {
//adds header to response
serverWebExchange.getResponse().getHeaders().set("CUSTOM-RESPONSE-HEADER",
HttpStatus.OK.equals(serverWebExchange.getResponse().getStatusCode()) ? "It worked": "It did not work");
return serverWebExchange;
})
.then();
}
6 項目使用
添加依賴：
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
配置Main啟動應用：
package com.pkslow.cloud.gateway;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class GatewayService {
public static void main(String[] args) {
SpringApplication.run(GatewayService.class, args);
}
}
配置路由：
server:
port: 8080
spring:
cloud:
gateway:
routes:
- id: pkslow
uri: https://www.pkslow.com
predicates:
- Path=/pkslow/**
filters:
- RewritePath=/pkslow(?<segment>.*), /$\{segment}
啟動后可正常訪問了：
7 總結
Spring Cloud Gateway實在是非常強大，能滿足微服務絕大多數應用場景了，還是很有必要了解一下的。
代碼請查看：https://github.com/LarryDpk/pkslow-samples
參考資料：官網
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