Spring Cloud Gateway Verification with Token

Introducing dependency

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-dependencies</artifactId>
      <version>${spring-cloud.version}</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-gateway</artifactId>
  </dependency>
</dependencies>

Custom filter

You can inherit AbstractGatewayFilterFactory or implement GlobalFilter to filter requests

GatewayFilter

GatewayFilter can only be applied on specified paths

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;

@Component
public class AuthGatewayFilterFactory extends AbstractGatewayFilterFactory<AuthGatewayFilterFactory.Config> {

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

  @Override
  public GatewayFilter apply(Config config) {
    return (exchange, chain) -> {
      System.out.println("Welcome to AuthFilter.");
      String token = exchange.getRequest().getHeaders().getFirst("sign");
      if (Config.secret.equals(token)) {
        return chain.filter(exchange);
      }
      ServerHttpResponse response = exchange.getResponse();
      response.setStatusCode(HttpStatus.UNAUTHORIZED);
      return response.setComplete();
    };
  }

  static class Config {
    static String secret = "1234";
  }
}

spring:
 cloud:
  gateway:
   routes:
   - id: service2_route
    uri: http://127.0.0.1:8082
    predicates:
    - Path=/s2/**
    filters:
    - StripPrefix=1 #  Remove the path's  n  Prefix 
    - Auth=true #  Enter the name prefix of the filter class 

GlobalFilter

GlobalFilter can be applied globally

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Component
public class AuthGlobalFilter implements GlobalFilter, Ordered {
  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    System.out.println("Welcome to AuthGlobalFilter.");
    ServerHttpRequest request = exchange.getRequest();
    String sign = request.getHeaders().get("sign").get(0);
    String token = "1234";
    if(token.equals(sign)) {
      return chain.filter(exchange);
    }
    ServerHttpResponse response = exchange.getResponse();
    response.setStatusCode(HttpStatus.UNAUTHORIZED);
    return response.setComplete();
  }

  @Override
  public int getOrder() {
    return 0;
  }
}