spring cloud gateway http method filter

httpmethodgatewayfilter

package com.cloud.gateway.app;

import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.setResponseStatus;

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.cloud.gateway.support.HttpStatusHolder;
import org.springframework.http.HttpMethod;
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 lombok.extern.slf4j.Slf4j;
import reactor.core.publisher.Mono;

/**
 * @author omidp
 *
 */
@Component
@Slf4j
public class HttpMethodGatewayFilter extends AbstractGatewayFilterFactory<HttpMethodGatewayFilter.Config> {

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

	public static class Config {

	}

	@Override
	public GatewayFilter apply(Config config) {
		return new GatewayFilter() {

			@Override
			public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
				ServerHttpRequest req = exchange.getRequest();
				if (HttpMethod.POST.equals(req.getMethod()) == false) {
					if (!exchange.getResponse().isCommitted()) {
						setResponseStatus(exchange, new HttpStatusHolder(HttpStatus.I_AM_A_TEAPOT, null));
						final ServerHttpResponse response = exchange.getResponse();
						return response.setComplete();
					}
					return Mono.empty();
				} else {
					Object httpMethod = req.getHeaders().get("action");
					if (httpMethod != null) {
						log.info("httpMethod action header {}", httpMethod);
						var mutatedExchange = exchange.mutate().request(req.mutate().method(HttpMethod.GET).build())
								.build();
						return chain.filter(mutatedExchange);
					}

					ServerHttpRequest request = req.mutate().build();
					return chain.filter(exchange.mutate().request(request).build());
				}
			}
		};
	}

}

spring:
cloud:
gateway:
routes:
- id: user-service
uri: lb://USER-SERVICE
predicates:
- Path=/user/**
filters:
- HttpMethodGatewayFilter
- RewritePath=/user/(?.*), /${path}
- name: CircuitBreaker
args:
name: cloudCircuitBreaker
fallbackUri: forward:/fallback