Building a simple microservice using Spring Boot version 3.1.3, which has two services one is api-gateway and another fisherman-service. API-Gateway is using cloud-gateway, eureka-cient and openfeign and the fisherman-service is a spring boot application that has exposed certain REST endpoins. While trying to access fisherman-service via feign-client service, getting exception.
pom.xml - Feign Client
<?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>3.1.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.techverse</groupId>
<artifactId>api-gateway-with-feign-and-eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>api-gateway-with-feign-and-eureka</name>
<description>api-gateway-with-feign-and-eureka</description>
<properties>
<java.version>17</java.version>
<spring-cloud.version>2022.0.4</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>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</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>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>
application.yml file: Feign Client
server:
port: 8089
spring:
application:
name: api-gateway-3
cloud:
gateway:
discovery:
locator:
enabled: true
eureka:
client:
register-with-eureka: true
fetch-registry: true
serviceUrl:
defaultZone: http://localhost:8761/eureka/
appication file: Feign-Client
@EnableFeignClients
@SpringBootApplication
@EnableDiscoveryClient
public class ApiGatewayWithFeignAndEurekaApplication {
public static void main(String[] args) {
SpringApplication.run(ApiGatewayWithFeignAndEurekaApplication.class, args);
}
}
Feign-Client interface
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.*;
@FeignClient(name = "FISHERMAN-SERVICE")
public interface FishermanClient {
@GetMapping("fm/msg")
String msg();
}
Feign-Client controller class
@RequestMapping(path = "/feign")
@RestController
public class FismermanCallingController {
@Autowired
private FishermanClient fishermanClient;
@GetMapping("/msg")
public String msg(){
String msg = fishermanClient.msg();
return msg;
}
}
Fisherman Service Controller Class:
@RestController
@RequestMapping(path = "/fm")
public class FishermanController {
private FishermanService fishermanService;
@Autowired
FishermanController(FishermanService fishermanService) {
this.fishermanService = fishermanService;
}
@GetMapping("/msg")
public String msg(){
return "Hello from Fisherman Service";
}
}
The fisherman service is up and running on the port 8082 and gives proper response while hitting the uri from postman or chrome.
URI: localhost:8082/fm/msg
Response: Hello from Fisherman Service
But when we try to access the same via feign client we get an exception.
URI: localhost:8089/feign/msg
Exception:
2023-09-02T20:56:56.287+05:30 ERROR 7944 --- [ctor-http-nio-7] a.w.r.e.AbstractErrorWebExceptionHandler : [72f710ac-3] 500 Server Error for HTTP GET "/feign/msg"
java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-7
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:86) ~[reactor-core-3.5.9.jar:3.5.9]
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
*__checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
*__checkpoint ⇢ HTTP GET "/feign/msg" [ExceptionHandlingWebHandler]
Original Stack Trace:
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:86) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Mono.block(Mono.java:1712) ~[reactor-core-3.5.9.jar:3.5.9]
at org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient.choose(BlockingLoadBalancerClient.java:163) ~[spring-cloud-loadbalancer-4.0.4.jar:4.0.4]
at org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient.execute(FeignBlockingLoadBalancerClient.java:118) ~[spring-cloud-openfeign-core-4.0.4.jar:4.0.4]
at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:100) ~[feign-core-12.4.jar:na]
at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:70) ~[feign-core-12.4.jar:na]
at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:96) ~[feign-core-12.4.jar:na]
at jdk.proxy2/jdk.proxy2.$Proxy109.msg(Unknown Source) ~[na:na]
at com.techverse.apigatewaywithfeignandeureka.controllers.FismermanCallingController.msg(FismermanCallingController.java:22) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
at org.springframework.web.reactive.result.method.InvocableHandlerMethod.lambda$invoke$0(InvocableHandlerMethod.java:145) ~[spring-webflux-6.0.11.jar:6.0.11]
at reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:152) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoFlatMap.subscribeOrReturn(MonoFlatMap.java:53) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:57) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:240) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.onComplete(MonoIgnoreThen.java:203) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onComplete(MonoFlatMap.java:189) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Operators.complete(Operators.java:137) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoZip.subscribe(MonoZip.java:121) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Mono.subscribe(Mono.java:4495) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:263) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:51) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:165) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:74) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:82) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.innerNext(FluxConcatMapNoPrefetch.java:258) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:863) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:180) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2545) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.request(MonoPeekTerminal.java:139) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:171) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.request(Operators.java:2305) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.request(FluxConcatMapNoPrefetch.java:338) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoNext$NextSubscriber.request(MonoNext.java:108) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2341) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2215) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoNext$NextSubscriber.onSubscribe(MonoNext.java:70) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.onSubscribe(FluxConcatMapNoPrefetch.java:164) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:201) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:83) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.Mono.subscribe(Mono.java:4495) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:263) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:51) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.core.publisher.MonoDeferContextual.subscribe(MonoDeferContextual.java:55) ~[reactor-core-3.5.9.jar:3.5.9]
at reactor.netty.http.server.HttpServer$HttpServerHandle.onStateChange(HttpServer.java:1052) ~[reactor-netty-http-1.1.10.jar:1.1.10]
at reactor.netty.ReactorNetty$CompositeConnectionObserver.onStateChange(ReactorNetty.java:710) ~[reactor-netty-core-1.1.10.jar:1.1.10]
at reactor.netty.transport.ServerTransport$ChildObserver.onStateChange(ServerTransport.java:481) ~[reactor-netty-core-1.1.10.jar:1.1.10]
at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:647) ~[reactor-netty-http-1.1.10.jar:1.1.10]
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:114) ~[reactor-netty-core-1.1.10.jar:1.1.10]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:238) ~[reactor-netty-http-1.1.10.jar:1.1.10]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346) ~[netty-codec-4.1.97.Final.jar:4.1.97.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318) ~[netty-codec-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.97.Final.jar:4.1.97.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.97.Final.jar:4.1.97.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.97.Final.jar:4.1.97.Final]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
And the fisherman-service is correctly registered at Eureka server with name "FISHERMAN-SERVICE"
