spring.cloud.kubernetes.discovery-server-url must be specified and a valid URL

[dpandipperuma]

Hi, i'm a newbie and i'm developing a sample spring cloud gateway application and i'm trying to access my microservices via service name. Below i have added my dependencies.

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.6</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>11</java.version>
        <spring-cloud.version>2021.0.6</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-circuitbreaker-resilience4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-kubernetes -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-kubernetes</artifactId>
            <version>1.1.5.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-actuator -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
            <version>3.0.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-kubernetes-ribbon -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-kubernetes-ribbon</artifactId>
            <version>1.1.5.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-loadbalancer -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
            <version>4.0.2</version>
        </dependency>

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

Then my application yaml file looks like below.

spring:
  application.name: gateway
  cloud:
    kubernetes:
      discovery:
        enabled: true
        all-namespaces: false
        include-not-ready-addresses: true
    gateway:
      discovery:
        locator:
          enabled: true
          lowerCaseServiceId: true

server:
  port: 8088
logging:
  level:
    org.springframework.cloud.gateway: TRACE
    org.springframework.cloud.loadbalancer: TRACE
management:
  endpoints:
    web:
      exposure:
        include: '*'
  endpoint:
    health:
      enabled: true
    info:
      enabled: true

I added the @EnableDiscoveryClient annotation like below in my main file.

@SpringBootApplication
@EnableDiscoveryClient
@RestController
public class DemoApplication {

    @Autowired
    private DiscoveryClient discoveryClient;

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

    @GetMapping("/services")
    public List<String> services() {
        return this.discoveryClient.getServices();
    }
}

But when i try to clean install, it gives below error.

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2023-04-11 13:03:56.489 ERROR 8096 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'discoveryClientRouteDefinitionLocator' defined in class path resource [org/springframework/cloud/gateway/discovery/GatewayDiscoveryClientAutoConfiguration$ReactiveDiscoveryClientRouteDefinitionLocatorConfiguration.class]: Unsatisfied dependency expressed through method 'discoveryClientRouteDefinitionLocator' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'reactiveCompositeDiscoveryClient' defined in class path resource [org/springframework/cloud/client/discovery/composite/reactive/ReactiveCompositeDiscoveryClientAutoConfiguration.class]: Unsatisfied dependency expressed through method 'reactiveCompositeDiscoveryClient' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'kubernetesReactiveDiscoveryClient' defined in class path resource [org/springframework/cloud/kubernetes/discovery/KubernetesDiscoveryClientAutoConfiguration$Reactive.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.client.discovery.ReactiveDiscoveryClient]: Factory method 'kubernetesReactiveDiscoveryClient' threw exception; nested **exception is org.springframework.cloud.kubernetes.discovery.DiscoveryServerUrlInvalidException: spring.cloud.kubernetes.discovery-server-url must be specified and a valid URL.**
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:541) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:953) ~[spring-beans-5.3.18.jar:5.3.18]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.18.jar:5.3.18]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.18.jar:5.3.18]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:740) ~[spring-boot-2.6.6.jar:2.6.6]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:415) ~[spring-boot-2.6.6.jar:2.6.6]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) ~[spring-boot-2.6.6.jar:2.6.6]
    at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:136) ~[spring-

I saw there is a configuration like this -> kubernetes.discovery.discovery-server-url: "". But what i cant understand is what should i put as the server-url here. Please note - I'm using minikube to locally deploy my applications.

What am i missing here ?

[wind57]

sorry for the late reply.

I am not exactly sure what you are trying to do here, but first of all the dependencies that you have are really old and un-supported anymore. For example: spring-cloud-starter-kubernetes-ribbon is not part of our repo anymore.

Now the exception that you get:

spring.cloud.kubernetes.discovery-server-url must be specified and a valid URL

is thrown by the kubernetesReactiveDiscoveryClient as seen in the logs. The exception is thrown here:

https://github.com/spring-cloud/spring-cloud-kubernetes/blob/main/spring-cloud-kubernetes-discovery/src/main/java/org/springframework/cloud/kubernetes/discovery/KubernetesReactiveDiscoveryClient.java#L36..#L38

But what is that property supposed to be? Well, in order to understand that, you need to understand what spring-cloud-kubernetes-discoveryserver docker image is, you can read more about it here

In very simple terms, that is an image that will discover kubernetes services and expose those to some endpoint. You can then query those endpoints (via the spring-cloud-kubernetes-discovery - which throws the Exceptino in your case) and get the information needed.

So the spring.cloud.kubernetes.discovery-server-url property is how you can reach the pod that encapsulates spring-cloud-kubernetes-discoveryserver docker image. Usually, this is via the service name.

We have an integration test that uses this property you could take a look at: https://github.com/spring-cloud/spring-cloud-kubernetes/blob/main/spring-cloud-kubernetes-integration-tests/spring-cloud-kubernetes-discoveryclient-it/src/test/java/org/springframework/cloud/kubernetes/discoveryclient/it/DiscoveryClientFilterNamespaceIT.java

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