My View and Experience: Troubleshoot API-Gateway

Monday, June 9, 2025

Troubleshoot API-Gateway

Create a Proper Test Controller

package com.example.api_gateway;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class ApiGatewayApplication {

    public static void main(String[] args) {
        SpringApplication.run(ApiGatewayApplication.class, args);
    }
}

@RestController
class TestController {
    
    @GetMapping("/gateway-test")
    public String testEndpoint() {
        return "Gateway is working properly!";
    }
}

2.Verify Service Accessibility

Create a simple test to ensure your greet service is reachable:

package com.example.api_gateway;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.function.client.WebClient;

@Configuration
class ServiceHealthCheck {
    
    @Bean
    public String checkGreetService() {
        WebClient.create("http://localhost:8001")
            .get()
            .uri("/greet")
            .retrieve()
            .toBodilessEntity()
            .subscribe(
                response -> System.out.println("Greet service is UP! Status: " + response.getStatusCode()),
                error -> System.err.println("Greet service is DOWN! Error: " + error.getMessage())
            );
        return "Health check initiated";
    }
}

3. Final Troubleshooting Steps

Remove any existing build artifacts:
bash
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```
mvn clean package
```

Check for port conflicts:

netstat -ano | findstr :9191
netstat -ano | findstr :8001

Verify service response:
bash
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```
curl -v http://localhost:8001/greet
```

Test gateway endpoints:

curl -v http://localhost:9191/gateway-test
curl -v http://localhost:9191/greet

Expected Behavior After Fix

http://localhost:9191/gateway-test should return:
text
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```
Gateway is working properly!
```
http://localhost:9191/greet should proxy to your service at http://localhost:8001/greet

If You Still Encounter Issues

Add this controller to debug routing:

package com.example.api_gateway;

import org.springframework.cloud.gateway.route.RouteLocator;
import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class DebugConfig {

    @Bean
    public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
        return builder.routes()
            .route("debug-greet-route", r -> r
                .path("/greet/**")
                .filters(f -> f.rewritePath("/greet/(?<segment>.*)", "/${segment}"))
                .uri("http://localhost:8001"))
            .route("direct-test", r -> r
                .path("/direct-test")
                .uri("http://httpbin.org/get"))
            .build();
    }
}

Then test:

http://localhost:9191/direct-test

This should return a response from httpbin.org, proving your gateway is working. If this works but /greet doesn't, the issue is with your service or the URI configuration.

My View and Experience