How do I resolve a 'unknown-host' error with Netflix Eureka service discovery?

Question

I am following a tutorial for the service discovery with Eureka. I downloaded my spring projects from start.spring.io. I have a Eureka server and two clients. My Eureka server picks up both services and show it on the web interface but when I try to send a get request to a service using the service name, I get the unknown host error. Here is my Eureka server:

I have already tried everything described in eureka unknownHostException in service discovery, but nothing worked

@SpringBootApplication
@EnableEurekaServer
public class DiscoveryServerApplication {

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

}

<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>2.7.12</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>io.javabrains</groupId>
    <artifactId>discovery-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>discovery-server</name>
    <description>Discovery Server</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>2021.0.7</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </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>

</project>

application.properties:

server.port=8761
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

movie-service-catalog:

<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>2.7.12</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>2021.0.7</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </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-starter-parent</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>

</project>

application.properties:

spring.application.name=movie-catalog-service
server.port=8081

@SpringBootApplication
@EnableEurekaClient
public class MovieCatalogServiceApplication {

    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }


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

}

@RestController
@RequestMapping("/catalog")
public class MovieCatalogResource {

    @Autowired
    private RestTemplate restTemplate;



    @RequestMapping("/{userId}")
    public List<CatalogItem> getCatalog(@PathVariable String userId){

        RestTemplate restTemplate = new RestTemplate();
        //get all rated movie IDs, movies user watched
        UserRating ratings = restTemplate.getForObject("http://ratings-data-service/ratingsdata/users/" + userId, UserRating.class);

        return ratings.getUserRating().stream().map(rating -> {
            //For each movie ID, call movie info service and details
            Movie movie = restTemplate.getForObject("http://movie-info-service/movies/" + rating.getMovieId(), Movie.class);
            //put them together
            return new CatalogItem(movie.getName(), "Test", rating.getRatings());
                }
        ).collect(Collectors.toList());



    }
}

ratings-data-service conf is same as movie-catalog-service enter image description here

Answer 1

According to my circumstances, I see several possibilities:

1. Make sure that your clients are configured to register with the Eureka server. In your client's configuration file make sure that you have set the following properties:

spring.application.name=name-of-your-service

eureka.client.serviceUrl.defaultZone=http://hostname:port/eureka/

2. Verify that your service names match what you have configured in your configuration files. The service name is the value of spring.application.name. Make sure that this value matches the name of the service you are trying to access.

3. try disabling any firewalls that may be blocking traffic between your Eureka server and client

4. Check the logs of Eureka server and clients to see if there are any errors. Look for messages related to registration and heartbeat.