Spring Boot (Webflux) - Swagger UI - redirect URI does not include Gateway Prefix. Fixes #2708

Author: bnasslahsen

springdoc-openapi-starter-webflux-ui/src/test/java/test/org/springdoc/ui/app32/SpringDocBehindProxyBasePathTest.java renamed to springdoc-openapi-starter-webflux-ui/src/test/java/test/org/springdoc/ui/app33/SpringDocBehindProxyBasePathTest.java

@@ -16,7 +16,7 @@
  *
  */
 
-package test.org.springdoc.ui.app32;
+package test.org.springdoc.ui.app33;
 
 import jakarta.annotation.PostConstruct;
 import org.junit.jupiter.api.Test;
@@ -37,8 +37,8 @@
 
 
 @SpringBootTest(webEnvironment = WebEnvironment.DEFINED_PORT,
-		properties = { //"spring.webflux.base-path=/test",
-				"server.forward-headers-strategy=native",
+		properties = { "spring.webflux.base-path=/test",
+				"server.forward-headers-strategy=framework",
 				"server.port=9318",
 				"springdoc.swagger-ui.path=/documentation/swagger-ui.html",
 				"springdoc.api-docs.path=/documentation/v3/api-docs",
@@ -47,7 +47,8 @@
 @Import(SpringDocConfig.class)
 public class SpringDocBehindProxyBasePathTest extends AbstractCommonTest {
 
-	private static final String X_FORWARD_PREFIX = "/path/prefix";
+	public static final String WEBFLUX_BASE_PATH = "/test";
+	public static final String X_FORWARD_PREFIX = "/path/prefix";
 
 	@LocalServerPort
 	private int port;
@@ -62,21 +63,22 @@ void init() {
 
 	@Test
 	public void testIndex() throws Exception {
-		HttpStatusCode httpStatusMono = webClient.get().uri("/documentation/swagger-ui.html")
+		HttpStatusCode httpStatusMono = webClient.get().uri(WEBFLUX_BASE_PATH+"/documentation/swagger-ui.html")
 				.header("X-Forwarded-Prefix", X_FORWARD_PREFIX)
 				.exchangeToMono(clientResponse -> Mono.just(clientResponse.statusCode())).block();
 		assertThat(httpStatusMono).isEqualTo(HttpStatus.FOUND);
 
-		httpStatusMono = webClient.get().uri("/documentation/webjars-pref/swagger-ui/index.html")
+		httpStatusMono = webClient.get().uri(WEBFLUX_BASE_PATH+"/documentation/webjars-pref/swagger-ui/index.html")
 				.header("X-Forwarded-Prefix", X_FORWARD_PREFIX)
 				.exchangeToMono(clientResponse -> Mono.just(clientResponse.statusCode())).block();
 		assertThat(httpStatusMono).isEqualTo(HttpStatus.OK);
 
-		String contentAsString = webClient.get().uri("/documentation/v3/api-docs/swagger-config")
+		String contentAsString = webClient.get().uri(WEBFLUX_BASE_PATH+"/documentation/v3/api-docs/swagger-config")
 				.header("X-Forwarded-Prefix", X_FORWARD_PREFIX)
 				.retrieve()
 				.bodyToMono(String.class).block();
-		String expected = getContent("results/app32-1.json");
+		
+		String expected = getContent("results/app33.json");
 		assertEquals(expected, contentAsString, true);
 	}
 

springdoc-openapi-starter-webflux-ui/src/test/java/test/org/springdoc/ui/app33/SpringDocConfig.java

@@ -0,0 +1,45 @@
+package test.org.springdoc.ui.app33;
+
+import java.util.List;
+
+import org.apache.commons.lang3.reflect.FieldUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.boot.autoconfigure.web.reactive.WebFluxProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.util.CollectionUtils;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.WebFilter;
+import org.springframework.web.server.WebFilterChain;
+
+@Configuration
+public class SpringDocConfig {
+
+	private static final Logger LOGGER = LoggerFactory.getLogger(SpringDocConfig.class);
+
+
+	@Bean
+	public WebFilter rewritePathWebFilter(WebFluxProperties webFluxProperties)  {
+		return (ServerWebExchange exchange, WebFilterChain chain) -> {
+			try {
+				ServerHttpRequest originalRequest = (ServerHttpRequest) FieldUtils.readDeclaredField(exchange.getRequest(), "originalRequest", true);
+				List<String> forwardedPrefixHeaders = originalRequest.getHeaders().get("X-Forwarded-Prefix");
+				if (!CollectionUtils.isEmpty(forwardedPrefixHeaders)) {
+					String forwardedPrefix = forwardedPrefixHeaders.get(0);
+					ServerHttpRequest mutatedRequest = exchange.getRequest().mutate()
+							.contextPath(forwardedPrefix + webFluxProperties.getBasePath())
+							.build();
+					ServerWebExchange mutatedExchange = exchange.mutate().request(mutatedRequest).build();
+					return chain.filter(mutatedExchange);
+				}
+
+			} catch (Exception e) {
+				LOGGER.error(e.getMessage());
+			}
+			return chain.filter(exchange);
+		};
+	}
+}

springdoc-openapi-starter-webflux-ui/src/test/resources/results/app33.json

@@ -0,0 +1,6 @@
+{
+  "configUrl": "/path/prefix/test/documentation/v3/api-docs/swagger-config",
+  "oauth2RedirectUrl": "http://localhost:9318/path/prefix/test/documentation/webjars-pref/swagger-ui/oauth2-redirect.html",
+  "url": "/path/prefix/test/documentation/v3/api-docs",
+  "validatorUrl": ""
+}