Unable to use spring cloud api gateway - spring-boot

Question

I am working on a sample poc and I am trying to integrate the spring cloud api gateway
In my pom.xml I have
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.tek</groupId>
<artifactId>gatewayApplication</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Gateway Application</name>
<description>Gateway Application for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>2021.0.3</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
and in my application.yml I have
server:
port: 9191
spring:
application:
name: API-GATEWAY
cloud:
gateway:
routes:
- id: DEPARTMENT-SERVICE
uri: lb://DEPARTMENT-SERVICE
predicates:
- Path=/departments/**
- id: USER-SERVICE
uri: lb://USER-SERVICE
predicates:
- Path=/user/**
In my main class
#SpringBootApplication
#EnableEurekaClient
public class GatewayApplication {
public static void main(String[] args) {
SpringApplication.run(GatewayApplication.class, args);
}
}
I am able to access the services directly from their respective ports , But when I try to access the api's from port gateway port ie 9191, I get
***2022-09-08 16:23:34.644 ERROR 4128 --- [ctor-http-nio-3] a.w.r.e.AbstractErrorWebExceptionHandler : [7e6c1cec-3] 500 Server Error for HTTP GET "/user/getUserDepartment/1"
java.net.UnknownHostException: Failed to resolve 'xxxxxxxx' after 5 queries
at io.netty.resolver.dns.DnsResolveContext.finishResolve(DnsResolveContext.java:1047) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
*__checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
__checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
__checkpoint ⇢ HTTP GET "/user/getUserDepartment/1" [ExceptionHandlingWebHandler]
Original Stack Trace:
at io.netty.resolver.dns.DnsResolveContext.finishResolve(DnsResolveContext.java:1047) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.resolver.dns.DnsResolveContext.tryToFinishResolve(DnsResolveContext.java:1000) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.resolver.dns.DnsResolveContext.query(DnsResolveContext.java:418) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.resolver.dns.DnsResolveContext.access$600(DnsResolveContext.java:66) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.resolver.dns.DnsResolveContext$2.operationComplete(DnsResolveContext.java:467) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:578) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:571) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:550) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:491) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:616) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.setFailure0(DefaultPromise.java:609) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.DefaultPromise.tryFailure(DefaultPromise.java:117) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.resolver.dns.DnsQueryContext.tryFailure(DnsQueryContext.java:256) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.resolver.dns.DnsQueryContext$4.run(DnsQueryContext.java:208) ~[netty-resolver-dns-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.PromiseTask.runTask(PromiseTask.java:98) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:153) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:174) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:167) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:470) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:503) ~[netty-transport-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.79.Final.jar:4.1.79.Final]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]
Caused by: io.netty.resolver.dns.DnsNameResolverTimeoutException: [/xxxxxxx] query via UDP timed out after 5000 milliseconds (no stack trace available)
*
Application.yml file of DepartmentService
server:
port: 9001
spring:
application:
name: DEPARTMENT-SERVICE
eureka:
client:
register-witheureka: true
fetch-registry: true
service-url:
defaultZone: http://localhost:8761/eureka/
instance:
hostname: localhost
prefer-ip-address: true

Answer 1

I solved it by adding eureka.instance.prefer-ip-address=true and eureka.instance.prefer-ip-address=true in application.properties of all the microservices which are using the gateway service.