Spring Cloud Gateway配置报错：UnknownHostException及413错误求助

Let's break down each of your problems and walk through the fixes step by step:

1. Fixing java.net.UnknownHostException for /get and /foo Routes #

This error typically means Gateway either can't resolve the external domain names or isn't using your proxy configuration correctly. Here's what to check:

a. Ensure Route URIs Are Fully Qualified #

Double-check the routes defined with RouteLocatorBuilder—make sure every uri starts with http:// or https://. If you skip the protocol prefix, Gateway will treat the value as a service name (for service discovery) instead of an external domain, which triggers host resolution failures.

Example of correct route configuration:

@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
    return builder.routes()
            .route("get_route", r -> r.path("/get")
                    .uri("http://httpbin.org")) // Full URI with protocol
            .route("foo_route", r -> r.path("/foo")
                    .uri("http://example.org")) // Same requirement here
            .build();
}

b. Use the Correct Proxy Configuration for Gateway #

Spring Cloud Gateway relies on Reactor Netty as its underlying HTTP client, so proxy settings need to target the Gateway client—not the server proxy settings (which apply to Tomcat for traditional Spring Boot web apps).

Update your application.yaml with the proper proxy setup:

spring:
  cloud:
    gateway:
      httpclient:
        proxy:
          host: your-proxy-server-host
          port: your-proxy-server-port
          # Add these lines if your proxy requires authentication
          username: your-proxy-username
          password: your-proxy-password

c. Validate Local Network Connectivity #

First test if your machine can reach the external domains directly. Run these commands in your terminal:

curl http://httpbin.org/get
curl http://example.org

If these fail, the issue lies with your network (e.g., company firewall blocking external traffic, DNS resolution errors). Reach out to your network admin, or try setting a public DNS server (like 8.8.8.8) on your machine to rule out DNS problems.

2. Fixing 413 Request Entity Too Large for /bling Route #

This error happens when the request body exceeds the maximum size allowed by Gateway (or the backend service it forwards to). Adjust these settings in application.yaml:

spring:
  cloud:
    gateway:
      # Limit for requests received by the Gateway server
      server:
        max-http-request-size: 10MB # Adjust to your needs (e.g., 100MB)
      # Limit for requests sent by Gateway's HTTP client to the backend
      httpclient:
        max-in-memory-size: 10MB

If the backend service (the one /bling routes to) also enforces a request size limit, you'll need to update its configuration too (for a Spring Boot backend, set server.max-http-request-size there as well).

内容的提问来源于stack exchange，提问作者Benjamin