Spring Boot 內置反向代理（Undertow Proxy）高可用配置

引言

在微服務架構中，反向代理是一個不可或缺的組件，它負責請求轉發、負載均衡、安全過濾等關鍵功能。

通常我們會選擇 Nginx、HAProxy 等專業反向代理組件，但在某些場景下，使用 Spring Boot 內置的反向代理功能可以簡化架構，減少運維復雜度。

本文將介紹如何利用 Undertow 服務器的反向代理能力，實現高可用的反向代理配置。

Undertow 簡介

Undertow 是一個采用 Java 開發的靈活的高性能 Web 服務器，提供基于 NIO 的阻塞和非阻塞 API。

作為 Spring Boot 支持的內嵌式服務器之一，它具有以下特點：

輕量級：核心僅依賴于 JBoss Logging 和 xnio
高性能：在多核系統上表現優異
內置反向代理：支持 HTTP、HTTPS、HTTP/2 代理
可擴展：通過 Handler 鏈模式支持靈活擴展

為什么選擇 Undertow 內置反向代理

在某些場景下，使用 Undertow 內置的反向代理功能比獨立部署 Nginx 等代理服務器更有優勢：

1. 簡化架構：減少額外組件，降低部署復雜度
2. 統一技術棧：全 Java 技術棧，便于開發團隊維護
3. 配置靈活：可通過代碼動態調整代理規則
4. 節約資源：適合資源有限的環境，如邊緣計算場景
5. 集成監控：與 Spring Boot 的監控體系無縫集成

基礎配置

步驟 1：添加 Undertow 依賴

首先，確保 Spring Boot 項目使用 Undertow 作為嵌入式服務器：

<?xml?version="1.0"?encoding="UTF-8"?>
<project?xmlns="http://maven.apache.org/POM/4.0.0"?xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0?https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>3.4.5</version><relativePath/></parent><groupId>demo</groupId><artifactId>springboot-undertow-proxy</artifactId><version>0.0.1-SNAPSHOT</version><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId><exclusions><exclusion><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-tomcat</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-undertow</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.32</version><scope>provided</scope></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>21</source><target>21</target><encoding>utf-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>3.2.0</version><executions><execution><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></build></project>

步驟 2：創建 Undertow 配置類

package?com.example.config;import?io.undertow.Handlers;
import?io.undertow.server.HttpHandler;
import?io.undertow.server.handlers.PathHandler;
import?io.undertow.server.handlers.RequestLimitingHandler;
import?io.undertow.server.handlers.ResponseCodeHandler;
import?io.undertow.server.handlers.proxy.LoadBalancingProxyClient;
import?io.undertow.server.handlers.proxy.ProxyHandler;
import?io.undertow.util.HeaderMap;
import?io.undertow.util.HttpString;
import?org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import?org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory;
import?org.springframework.boot.web.server.WebServerFactoryCustomizer;
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;
import?org.xnio.OptionMap;import?java.net.URI;@Configuration
public?class?UndertowProxyConfig?{@Bean@ConditionalOnProperty(name?=?"user.enabled",?havingValue?=?"false",?matchIfMissing?=?true)public?WebServerFactoryCustomizer<UndertowServletWebServerFactory>?undertowProxyCustomizer()?{return?factory?->?factory.addDeploymentInfoCustomizers(deploymentInfo?->?{deploymentInfo.addInitialHandlerChainWrapper(handler?->?{PathHandler?pathHandler?=?Handlers.path(handler);//?配置代理路由HttpHandler?handler1?=?createProxyClient("http://127.0.0.1:8081/user");HttpHandler?handler2?=?createProxyClient("http://127.0.0.2:8081/user/users2");handler1?=?secureProxyHandler(handler1);handler1?=?createRateLimitingHandler(handler1);//?添加路由規則pathHandler.addPrefixPath("/user",?handler1);pathHandler.addPrefixPath("/user/users2",?handler2);return?pathHandler;});});}private?HttpHandler?createProxyClient(String?targetUrl)?{try?{URI?uri?=?new?URI(targetUrl);LoadBalancingProxyClient?proxyClient?=?new?LoadBalancingProxyClient();proxyClient.addHost(uri);proxyClient.setConnectionsPerThread(20).setMaxQueueSize(10).setSoftMaxConnectionsPerThread(20).setProblemServerRetry(5).setTtl(30000);return?ProxyHandler.builder().setProxyClient(proxyClient).setMaxRequestTime(30000).setRewriteHostHeader(false).setReuseXForwarded(true).build();}?catch?(Exception?e)?{throw?new?RuntimeException("創建代理客戶端失敗",?e);}}private?HttpHandler?secureProxyHandler(HttpHandler?proxyHandler)?{return?exchange?->?{//?移除敏感頭部HeaderMap?headers?=?exchange.getRequestHeaders();headers.remove("X-Forwarded-Server");//?添加安全頭部exchange.getResponseHeaders().add(new?HttpString("X-XSS-Protection"),?"1;?mode=block");exchange.getResponseHeaders().add(new?HttpString("X-Content-Type-Options"),?"nosniff");exchange.getResponseHeaders().add(new?HttpString("X-Frame-Options"),?"DENY");//?添加代理信息headers.add(new?HttpString("X-Forwarded-For"),?exchange.getSourceAddress().getAddress().getHostAddress());headers.add(new?HttpString("X-Forwarded-Proto"),?exchange.getRequestScheme());headers.add(new?HttpString("X-Forwarded-Host"),?exchange.getHostName());proxyHandler.handleRequest(exchange);};}private?HttpHandler?createRateLimitingHandler(HttpHandler?next)?{//?根據實際情況調整return?new?RequestLimitingHandler(1,1,next);}}

高可用配置

要實現真正的高可用反向代理，需要考慮以下幾個關鍵方面：

1. 負載均衡策略

Undertow 提供多種負載均衡策略，可以根據需求選擇：

@Bean
public?LoadBalancingProxyClient?loadBalancingProxyClient()?{LoadBalancingProxyClient?loadBalancer?=?new?LoadBalancingProxyClient();//?配置負載均衡策略loadBalancer.setRouteParsingStrategy(RouteParsingStrategy.RANKED);loadBalancer.setConnectionsPerThread(20);//?添加后端服務器loadBalancer.addHost(new?URI("http://backend1:8080"));loadBalancer.addHost(new?URI("http://backend2:8080"));loadBalancer.addHost(new?URI("http://backend3:8080"));//?設置會話親和性（可選）loadBalancer.addSessionCookieName("JSESSIONID");return?loadBalancer;
}

2. 健康檢查與自動故障轉移

實現定期健康檢查，自動剔除不健康節點：

package?com.example.config;import?io.undertow.server.handlers.proxy.LoadBalancingProxyClient;
import?lombok.Data;
import?lombok.extern.slf4j.Slf4j;
import?org.springframework.beans.factory.annotation.Value;
import?org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import?org.springframework.http.ResponseEntity;
import?org.springframework.scheduling.annotation.Scheduled;
import?org.springframework.stereotype.Component;
import?org.springframework.web.client.RestTemplate;import?java.net.URI;
import?java.net.URISyntaxException;
import?java.util.Arrays;
import?java.util.List;
import?java.util.stream.Collectors;@Component
@ConditionalOnProperty(name?=?"user.enabled",?havingValue?=?"false",?matchIfMissing?=?true)
@Slf4j
public?class?BackendHealthMonitor?{private?final?LoadBalancingProxyClient?loadBalancer;private?final?List<URI>?backendServers;private?final?RestTemplate?restTemplate;public?BackendHealthMonitor(@Value("#{'${user.backends}'.split(',')}")?String[]?backends,LoadBalancingProxyClient?loadBalancer)?throws?URISyntaxException?{this.loadBalancer?=?loadBalancer;this.restTemplate?=?new?RestTemplate();this.backendServers?=?Arrays.stream(backends).map(url?->?{try?{return?new?URI(url);}?catch?(URISyntaxException?e)?{throw?new?RuntimeException(e);}}).collect(Collectors.toList());}@Scheduled(fixedDelay?=?10000)?//?每10秒檢查一次public?void?checkBackendHealth()?{for?(URI?server?:?backendServers)?{try?{String?healthUrl?=?server.getScheme()?+?"://"?+?server.getHost()?+?":"?+?server.getPort()?+?"/health";ResponseEntity<String>?response?=?restTemplate.getForEntity(healthUrl,?String.class);if?(response.getStatusCode().is2xxSuccessful())?{loadBalancer.addHost(server);log.info("后端服務?{}?狀態正常，已添加到負載均衡",?server);}?else?{//?服務不健康，從負載均衡器中移除loadBalancer.removeHost(server);log.warn("后端服務?{}?狀態異常，已從負載均衡中移除",?server);}}?catch?(Exception?e)?{//?連接異常，從負載均衡器中移除loadBalancer.removeHost(server);log.error("后端服務?{}?連接異常:?{}",?server,?e.getMessage());}}}
}

3. 集群高可用

為確保被代理服務的高可用，可配置多個代理實例：

user:backends:?"http://127.0.0.1:8081,http://127.0.0.2:8081"

性能優化

要獲得最佳性能，需要調整 Undertow 的相關參數（需要根據項目實際情況進行測試調整）：

server:undertow:threads:?io:?8??????????????????????#?IO線程數，建議設置為CPU核心數worker:?64?????????????????#?工作線程數，IO線程數的8倍buffer-size:?16384???????????#?緩沖區大小direct-buffers:?true?????????#?使用直接緩沖區max-http-post-size:?10485760?#?最大POST大小max-parameters:?2000?????????#?最大參數數量max-headers:?200?????????????#?最大請求頭數量max-cookies:?200?????????????#?最大Cookie數量

連接池優化

@Bean
public?UndertowServletWebServerFactory?undertowFactory()?{UndertowServletWebServerFactory?factory?=?new?UndertowServletWebServerFactory();factory.addBuilderCustomizers(builder?->?{builder.setSocketOption(Options.KEEP_ALIVE,?true).setSocketOption(Options.TCP_NODELAY,?true).setSocketOption(Options.REUSE_ADDRESSES,?true).setSocketOption(Options.BACKLOG,?10000).setServerOption(UndertowOptions.MAX_ENTITY_SIZE,?16?*?1024?*?1024L).setServerOption(UndertowOptions.IDLE_TIMEOUT,?60?*?1000).setServerOption(UndertowOptions.REQUEST_PARSE_TIMEOUT,?30?*?1000).setServerOption(UndertowOptions.NO_REQUEST_TIMEOUT,?60?*?1000).setServerOption(UndertowOptions.MAX_CONCURRENT_REQUESTS_PER_CONNECTION,?200);});return?factory;
}

安全強化

反向代理需要考慮安全性，可以添加以下配置：

1. 請求頭過濾與重寫

private?HttpHandler?secureProxyHandler(HttpHandler?proxyHandler)?{return?exchange?->?{//?移除敏感頭部HeaderMap?headers?=?exchange.getRequestHeaders();headers.remove("X-Forwarded-Server");//?添加安全頭部exchange.getResponseHeaders().add(new?HttpString("X-XSS-Protection"),?"1;?mode=block");exchange.getResponseHeaders().add(new?HttpString("X-Content-Type-Options"),?"nosniff");exchange.getResponseHeaders().add(new?HttpString("X-Frame-Options"),?"DENY");//?添加代理信息headers.add(new?HttpString("X-Forwarded-For"),?exchange.getSourceAddress().getAddress().getHostAddress());headers.add(new?HttpString("X-Forwarded-Proto"),?exchange.getRequestScheme());headers.add(new?HttpString("X-Forwarded-Host"),?exchange.getHostName());proxyHandler.handleRequest(exchange);};
}

2. 請求限流

private?HttpHandler?createRateLimitingHandler(HttpHandler?next)?{return?new?RequestLimitingHandler(100,next);
}

實際案例：某系統 API 網關

以一個電商系統為例，展示 Undertow 反向代理的實際應用：

package?com.example.config;import?io.undertow.Handlers;
import?io.undertow.server.HttpHandler;
import?io.undertow.server.handlers.PathHandler;
import?io.undertow.server.handlers.proxy.LoadBalancingProxyClient;
import?io.undertow.server.handlers.proxy.ProxyHandler;
import?org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory;
import?org.springframework.boot.web.server.WebServerFactoryCustomizer;
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;import?java.net.URI;@Configuration
public?class?EcommerceProxyConfig?{@Beanpublic?WebServerFactoryCustomizer<UndertowServletWebServerFactory>?ecommerceProxyCustomizer()?{return?factory?->?factory.addDeploymentInfoCustomizers(deploymentInfo?->?{deploymentInfo.addInitialHandlerChainWrapper(handler?->?{PathHandler?pathHandler?=?Handlers.path(handler);try?{//?用戶服務代理LoadBalancingProxyClient?userServiceClient?=?new?LoadBalancingProxyClient();userServiceClient.addHost(new?URI("http://user-service-1:8080/api/users"));userServiceClient.addHost(new?URI("http://user-service-2:8080/api/users"));//?商品服務代理LoadBalancingProxyClient?productServiceClient?=?new?LoadBalancingProxyClient();productServiceClient.addHost(new?URI("http://product-service-1:8080/api/products"));productServiceClient.addHost(new?URI("http://product-service-2:8080/api/products"));//?訂單服務代理LoadBalancingProxyClient?orderServiceClient?=?new?LoadBalancingProxyClient();orderServiceClient.addHost(new?URI("http://order-service-1:8080/api/orders"));orderServiceClient.addHost(new?URI("http://order-service-2:8080/api/orders"));//?路由規則pathHandler.addPrefixPath("/api/users",?createProxyHandler(userServiceClient));pathHandler.addPrefixPath("/api/products",?createProxyHandler(productServiceClient));pathHandler.addPrefixPath("/api/orders",?createProxyHandler(orderServiceClient));return?pathHandler;}catch?(Exception?e){throw?new?RuntimeException(e);}});});}private?HttpHandler?createProxyHandler(LoadBalancingProxyClient?client)?{return?ProxyHandler.builder().setProxyClient(client).setMaxRequestTime(30000).setRewriteHostHeader(true).build();}
}