Here’s the next article in a series of “Quick Guide to…”. This time we will discuss and run examples of Spring Boot microservices on Kubernetes. The structure of that article will be quite similar to this one Quick Guide to Microservices with Spring Boot 2.0, Eureka and Spring Cloud, as they are describing the same aspects of applications development. I’m going to focus on showing you the differences and similarities in development between for Spring Cloud and for Kubernetes. The topics covered in this article are:
- Using Spring Boot 2.0 in cloud-native development
- Providing service discovery for all microservices using Spring Cloud Kubernetes project
- Injecting configuration settings into application pods using Kubernetes Config Maps and Secrets
- Building application images using Docker and deploying them on Kubernetes using YAML configuration files
- Using Spring Cloud Kubernetes together with Zuul proxy to expose a single Swagger API documentation for all microservices
Spring Cloud and Kubernetes may be threaten as a competitive solutions when you build microservices environment. Such components like Eureka, Spring Cloud Config or Zuul provided by Spring Cloud may be replaced by built-in Kubernetes objects like services, config maps, secrets or ingresses. But even if you decide to use Kubernetes components instead of Spring Cloud you can take advantage of some interesting features provided throughout the whole Spring Cloud project.
The one raelly interesting project that helps us in development is Spring Cloud Kubernetes (https://github.com/spring-cloud-incubator/spring-cloud-kubernetes). Although it is still in incubation stage it is definitely worth to dedicating some time to it. It integrates Spring Cloud with Kubernetes. I’ll show you how to use implementation of discovery client, inter-service communication with Ribbon client and Zipkin discovery using Spring Cloud Kubernetes.
Before we proceed to the source code, let’s take a look on the following diagram. It illustrates the architecture of our sample system. It is quite similar to the architecture presented in the already mentioned article about microservices on Spring Cloud. There are three independent applications (employee-service
, department-service
, organization-service
), which communicate between each other through REST API. These Spring Boot microservices use some build-in mechanisms provided by Kubernetes: config maps and secrets for distributed configuration, etcd for service discovery, and ingresses for API gateway.
Let’s proceed to the implementation. Currently, the newest stable version of Spring Cloud is Finchley.RELEASE
. This version of spring-cloud-dependencies
should be declared as a BOM for dependency management.
<dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>Finchley.RELEASE</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement>
Spring Cloud Kubernetes is not released under Spring Cloud Release Trains. So, we need to explicitly define its version. Because we use Spring Boot 2.0 we have to include the newest SNAPSHOT
version of spring-cloud-kubernetes
artifacts, which is 0.3.0.BUILD-SNAPSHOT
.
The source code of sample applications presented in this article is available on GitHub in repository https://github.com/piomin/sample-spring-microservices-kubernetes.git.
Pre-requirements
In order to be able to deploy and test our sample microservices we need to prepare a development environment. We can realize that in the following steps:
- You need at least a single node cluster instance of Kubernetes (Minikube) or Openshift (Minishift) running on your local machine. You should start it and expose embedded Docker client provided by both of them. The detailed intruction for Minishift may be found there: Quick guide to deploying Java apps on OpenShift. You can also use that description to run Minikube – just replace word ‘minishift’ with ‘minikube’. In fact, it does not matter if you choose Kubernetes or Openshift – the next part of this tutorial would be applicable for both of them
- Spring Cloud Kubernetes requires access to Kubernetes API in order to be able to retrieve a list of address of pods running for a single service. If you use Kubernetes you should just execute the following command:
$ kubectl create clusterrolebinding admin --clusterrole=cluster-admin --serviceaccount=default:default
If you deploy your microservices on Minishift you should first enable admin-user addon, then login as a cluster admin, and grant required permissions.
$ minishift addons enable admin-user $ oc login -u system:admin $ oc policy add-role-to-user cluster-reader system:serviceaccount:myproject:default
- All our sample microservices use MongoDB as a backend store. So, you should first run an instance of this database on your node. With Minishift it is quite simple, as you can use predefined templates just by selecting service Mongo on the Catalog list. With Kubernetes the task is more difficult. You have to prepare deployment configuration files by yourself and apply it to the cluster. All the configuration files are available under kubernetes directory inside sample Git repository. To apply the following YAML definition to the cluster you should execute command
kubectl apply -f kubernetes\mongo-deployment.yaml
. After it Mongo database would be available under the namemongodb
inside Kubernetes cluster.
apiVersion: apps/v1 kind: Deployment metadata: name: mongodb labels: app: mongodb spec: replicas: 1 selector: matchLabels: app: mongodb template: metadata: labels: app: mongodb spec: containers: - name: mongodb image: mongo:latest ports: - containerPort: 27017 env: - name: MONGO_INITDB_DATABASE valueFrom: configMapKeyRef: name: mongodb key: database-name - name: MONGO_INITDB_ROOT_USERNAME valueFrom: secretKeyRef: name: mongodb key: database-user - name: MONGO_INITDB_ROOT_PASSWORD valueFrom: secretKeyRef: name: mongodb key: database-password --- apiVersion: v1 kind: Service metadata: name: mongodb labels: app: mongodb spec: ports: - port: 27017 protocol: TCP selector: app: mongodb
1. Inject configuration with Config Maps and Secrets
When using Spring Cloud the most obvious choice for realizing distributed configuration in your system is Spring Cloud Config. With Kubernetes you can use Config Map. It holds key-value pairs of configuration data that can be consumed in pods or used to store configuration data. It is used for storing and sharing non-sensitive, unencrypted configuration information. To use sensitive information in your clusters, you must use Secrets. An usage of both these Kubernetes objects can be perfectly demonstrated basing on the example of MongoDB connection settings. Inside Spring Boot application we can easily inject it using environment variables. Here’s fragment of application.yml
file with URI configuration.
spring: data: mongodb: uri: mongodb://${MONGO_USERNAME}:${MONGO_PASSWORD}@mongodb/${MONGO_DATABASE}
While username or password are a sensitive fields, a database name is not. So we can place it inside config map.
apiVersion: v1 kind: ConfigMap metadata: name: mongodb data: database-name: microservices
Of course, username and password are defined as secrets.
apiVersion: v1 kind: Secret metadata: name: mongodb type: Opaque data: database-password: MTIzNDU2 database-user: cGlvdHI=
To apply the configuration to Kubernetes cluster we run the following commands.
$ kubectl apply -f kubernetes/mongodb-configmap.yaml $ kubectl apply -f kubernetes/mongodb-secret.yaml
After it we should inject the configuration properties into application’s pods. When defining container configuration inside Deployment YAML file we have to include references to environment variables and secrets as shown below
apiVersion: apps/v1 kind: Deployment metadata: name: employee labels: app: employee spec: replicas: 1 selector: matchLabels: app: employee template: metadata: labels: app: employee spec: containers: - name: employee image: piomin/employee:1.0 ports: - containerPort: 8080 env: - name: MONGO_DATABASE valueFrom: configMapKeyRef: name: mongodb key: database-name - name: MONGO_USERNAME valueFrom: secretKeyRef: name: mongodb key: database-user - name: MONGO_PASSWORD valueFrom: secretKeyRef: name: mongodb key: database-password
2. Building service discovery with Kubernetes
We usually running microservices on Kubernetes using Docker containers. One or more containers are grouped by pods, which are the smallest deployable units created and managed in Kubernetes. A good practice is to run only one container inside a single pod. If you would like to scale up your microservice you would just have to increase a number of running pods. All running pods that belong to a single microservice are logically grouped by Kubernetes Service. This service may be visible outside the cluster, and is able to load balance incoming requests between all running pods. The following service definition groups all pods labelled with field app
equaled to employee
.
apiVersion: v1 kind: Service metadata: name: employee labels: app: employee spec: ports: - port: 8080 protocol: TCP selector: app: employee
Service can be used for accessing application outside Kubernetes cluster or for inter-service communication inside a cluster. However, the communication between microservices can be implemented more comfortable with Spring Cloud Kubernetes. First we need to include the following dependency to project pom.xml
.
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-kubernetes</artifactId> <version>0.3.0.BUILD-SNAPSHOT</version> </dependency>
Then we should enable discovery client for an application – the same as we have always done for discovery Spring Cloud Netflix Eureka. This allows you to query Kubernetes endpoints (services) by name. This discovery feature is also used by the Spring Cloud Kubernetes Ribbon or Zipkin projects to fetch respectively the list of the pods defined for a microservice to be load balanced or the Zipkin servers available to send the traces or spans.
@SpringBootApplication @EnableDiscoveryClient @EnableMongoRepositories @EnableSwagger2 public class EmployeeApplication { public static void main(String[] args) { SpringApplication.run(EmployeeApplication.class, args); } // ... }
The last important thing in this section is to guarantee that Spring application name would be exactly the same as Kubernetes service name for the application. For application employee-service
it is employee
.
spring: application: name: employee
3. Building microservice using Docker and deploying on Kubernetes
There is nothing unusual in our sample microservices. We have included some standard Spring dependencies for building REST-based microservices, integrating with MongoDB and generating API documentation using Swagger2.
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger2</artifactId> <version>2.9.2</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-mongodb</artifactId> </dependency>
In order to integrate with MongoDB we should create interface that extends standard Spring Data CrudRepository
.
public interface EmployeeRepository extends CrudRepository { List findByDepartmentId(Long departmentId); List findByOrganizationId(Long organizationId); }
Entity class should be annotated with Mongo @Document
and a primary key field with @Id
.
@Document(collection = "employee") public class Employee { @Id private String id; private Long organizationId; private Long departmentId; private String name; private int age; private String position; // ... }
The repository bean has been injected to the controller class. Here’s the full implementation of our REST API inside employee-service.
@RestController public class EmployeeController { private static final Logger LOGGER = LoggerFactory.getLogger(EmployeeController.class); @Autowired EmployeeRepository repository; @PostMapping("/") public Employee add(@RequestBody Employee employee) { LOGGER.info("Employee add: {}", employee); return repository.save(employee); } @GetMapping("/{id}") public Employee findById(@PathVariable("id") String id) { LOGGER.info("Employee find: id={}", id); return repository.findById(id).get(); } @GetMapping("/") public Iterable findAll() { LOGGER.info("Employee find"); return repository.findAll(); } @GetMapping("/department/{departmentId}") public List findByDepartment(@PathVariable("departmentId") Long departmentId) { LOGGER.info("Employee find: departmentId={}", departmentId); return repository.findByDepartmentId(departmentId); } @GetMapping("/organization/{organizationId}") public List findByOrganization(@PathVariable("organizationId") Long organizationId) { LOGGER.info("Employee find: organizationId={}", organizationId); return repository.findByOrganizationId(organizationId); } }
In order to run our microservices on Kubernetes we should first build the whole Maven project with mvn clean install
command. Each microservice has Dockerfile placed in the root directory. Here’s Dockerfile definition for employee-service
.
FROM openjdk:8-jre-alpine ENV APP_FILE employee-service-1.0-SNAPSHOT.jar ENV APP_HOME /usr/apps EXPOSE 8080 COPY target/$APP_FILE $APP_HOME/ WORKDIR $APP_HOME ENTRYPOINT ["sh", "-c"] CMD ["exec java -jar $APP_FILE"]
Let’s build Docker images for all three sample microservices.
$ cd employee-service $ docker build -t piomin/employee:1.0 . $ cd department-service $ docker build -t piomin/department:1.0 . $ cd organization-service $ docker build -t piomin/organization:1.0 .
The last step is to deploy Docker containers with applications on Kubernetes. To do that just execute commands kubectl apply
on YAML configuration files. The sample deployment file for employee-service
has been demonstrated in step 1. All required deployment fields are available inside project repository in kubernetes
directory.
$ kubectl apply -f kubernetes\employee-deployment.yaml $ kubectl apply -f kubernetes\department-deployment.yaml $ kubectl apply -f kubernetes\organization-deployment.yaml
4. Communication between microservices with Spring Cloud Kubernetes Ribbon
All the microservice are deployed on Kubernetes. Now, it’s worth to discuss some aspects related to inter-service communication. Application employee-service
in contrast to other microservices did not invoke any other microservices. Let’s take a look on to other microservices that calls API exposed by employee-service
and communicates between each other (organization-service
calls department-service
API).
First we need to include some additional dependencies to the project. We use Spring Cloud Ribbon and OpenFeign. Alternatively you can also use Spring @LoadBalanced
RestTemplate
.
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-kubernetes-ribbon</artifactId> <version>0.3.0.BUILD-SNAPSHOT</version> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency>
Here’s the main class of department-service
. It enables Feign client using @EnableFeignClients
annotation. It works the same as with discovery based on Spring Cloud Netflix Eureka. OpenFeign uses Ribbon for client-side load balancing. Spring Cloud Kubernetes Ribbon provides some beans that forces Ribbon to communicate with Kubernetes API through Fabric8 KubernetesClient
.
@SpringBootApplication @EnableDiscoveryClient @EnableFeignClients @EnableMongoRepositories @EnableSwagger2 public class DepartmentApplication { public static void main(String[] args) { SpringApplication.run(DepartmentApplication.class, args); } // ... }
Here’s implementation of Feign client for calling method exposed by employee-service
.
@FeignClient(name = "employee") public interface EmployeeClient { @GetMapping("/department/{departmentId}") List findByDepartment(@PathVariable("departmentId") String departmentId); }
Finally, we have to inject Feign client’s beans to the REST controller. Now, we may call the method defined inside EmployeeClient
, which is equivalent to calling REST endpoints.
@RestController public class DepartmentController { private static final Logger LOGGER = LoggerFactory.getLogger(DepartmentController.class); @Autowired DepartmentRepository repository; @Autowired EmployeeClient employeeClient; // ... @GetMapping("/organization/{organizationId}/with-employees") public List findByOrganizationWithEmployees(@PathVariable("organizationId") Long organizationId) { LOGGER.info("Department find: organizationId={}", organizationId); List departments = repository.findByOrganizationId(organizationId); departments.forEach(d -> d.setEmployees(employeeClient.findByDepartment(d.getId()))); return departments; } }
5. Building API gateway using Kubernetes Ingress
An Ingress is a collection of rules that allow incoming requests to reach the downstream services. In our microservices architecture ingress is playing a role of an API gateway. To create it we should first prepare YAML description file. The descriptor file should contain the hostname under which the gateway will be available and mapping rules to the downstream services.
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: gateway-ingress annotations: nginx.ingress.kubernetes.io/rewrite-target: / spec: backend: serviceName: default-http-backend servicePort: 80 rules: - host: microservices.info http: paths: - path: /employee backend: serviceName: employee servicePort: 8080 - path: /department backend: serviceName: department servicePort: 8080 - path: /organization backend: serviceName: organization servicePort: 8080
You have to execute the following command to apply the configuration visible above to the Kubernetes cluster.
$ kubectl apply -f kubernetes\ingress.yaml
For testing this solution locally we have to insert the mapping between IP address and hostname set in ingress definition inside hosts
file as shown below. After it we can services through ingress using defined hostname just like that: http://microservices.info/employee
.
192.168.99.100 microservices.info
You can check the details of created ingress just by executing command kubectl describe ing gateway-ingress
.
6. Enabling API specification on gateway using Swagger2
Ok, what if we would like to expose single swagger documentation for all microservices deployed on Kubernetes? Well, here the things are getting complicated… We can run container with Swagger UI, and map all paths exposed by the ingress manually, but it is rather not a good solution…
In that case we can use Spring Cloud Kubernetes Ribbon one more time – this time together with Spring Cloud Netflix Zuul. Zuul will act as gateway only for serving Swagger API.
Here’s the list of dependencies used in my gateway-service
project.
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-zuul</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-kubernetes</artifactId> <version>0.3.0.BUILD-SNAPSHOT</version> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-kubernetes-ribbon</artifactId> <version>0.3.0.BUILD-SNAPSHOT</version> </dependency> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger-ui</artifactId> <version>2.9.2</version> </dependency> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger2</artifactId> <version>2.9.2</version> </dependency>
Kubernetes discovery client will detect all services exposed on cluster. We would like to display documentation only for our three microservices. That’s why I defined the following routes for Zuul.
zuul: routes: department: path: /department/** employee: path: /employee/** organization: path: /organization/**
Now we can use ZuulProperties
bean to get routes addresses from Kubernetes discovery, and configure them as Swagger resources as shown below.
@Configuration public class GatewayApi { @Autowired ZuulProperties properties; @Primary @Bean public SwaggerResourcesProvider swaggerResourcesProvider() { return () -> { List resources = new ArrayList(); properties.getRoutes().values().stream() .forEach(route -> resources.add(createResource(route.getId(), "2.0"))); return resources; }; } private SwaggerResource createResource(String location, String version) { SwaggerResource swaggerResource = new SwaggerResource(); swaggerResource.setName(location); swaggerResource.setLocation("/" + location + "/v2/api-docs"); swaggerResource.setSwaggerVersion(version); return swaggerResource; } }
Application gateway-service
should be deployed on cluster the same as other applications. You can the list of running service by executing command kubectl get svc
. Swagger documentation is available under address http://192.168.99.100:31237/swagger-ui.html
.
Conclusion
I’m actually rooting for Spring Cloud Kubernetes project, which is still at the incubation stage. Kubernetes popularity as a platform is rapidly growing during some last months, but it still has some weaknesses. One of them is inter-service communication. Kubernetes doesn’t give us many mechanisms out-of-the-box, which allows configure more advanced rules. This a reason for creating frameworks for service mesh on Kubernetes like Istio or Linkerd. While these projects are still relatively new solutions, Spring Cloud is stable, opinionated framework. Why not to use to provide service discovery, inter-service communication or load balancing? Thanks to Spring Cloud Kubernetes it is possible.
This is really great informative blog. Keep sharing.
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Thanks 🙂
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This sample Spring Cloud K8S integration is no long available. Is there a problem with it? https://github.com/piomin/sample-spring-microservices-kubernetes.git.
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No there is no problem since it has been moved to Spring repository
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Out of curiosity – is there any alternative to suggested service-discovery, apart from RBAC changes?
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Yes, there are some alternatives. For example , you can use Consul or Spring Cloud Eureka as a discovery server.
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Firstly, Thank you in advance for your sharing. I have a small question
I got error when deploy gateway-service :
“`
io.fabric8.kubernetes.client.KubernetesClientException: Failure executing: GET at: https://kubernetes.default.svc/api/v1/namespaces/default/services. Message: Forbidden!Configured service account doesn’t have access. Service account may have been revoked. services is forbidden: User “system:serviceaccount:default:default” cannot list services in the namespace “default”.
“`
Although I’ve enabled ingress in minikube:
minikube addons enable ingress
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I found this on Stackoverflow :
https://stackoverflow.com/questions/47973570/kubernetes-log-user-systemserviceaccountdefaultdefault-cannot-get-services
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This usually happens when the proper authorizations are missing for User “system:serviceaccount:default:default” in your Kubernetes cluster.
See https://github.com/fabric8io/fabric8/issues/6840#issuecomment-307560275 (comment) for a solution.
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As I have mentioned in my article, you have to run the command: $ kubectl create clusterrolebinding admin –clusterrole=cluster-admin –serviceaccount=default:default on your minikube instance to enable an access to Kubernetes API from your pods.
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Hi Piotr,
I followed your blog and when I start pods with department / employee service I am getting following error (Did you maybe encounter something similar):
2019-02-07 16:08:38 ERROR [-,,,] Application run failed
java.lang.AbstractMethodError: null
at org.springframework.core.OrderComparator.findOrder(OrderComparator.java:142) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.annotation.AnnotationAwareOrderComparator.findOrder(AnnotationAwareOrderComparator.java:65) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.getOrder(OrderComparator.java:125) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.getOrder(OrderComparator.java:113) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.doCompare(OrderComparator.java:82) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.compare(OrderComparator.java:68) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at java.util.TimSort.countRunAndMakeAscending(TimSort.java:360) ~[na:1.8.0_191]
at java.util.TimSort.sort(TimSort.java:220) ~[na:1.8.0_191]
at java.util.Arrays.sort(Arrays.java:1512) ~[na:1.8.0_191]
at java.util.ArrayList.sort(ArrayList.java:1462) ~[na:1.8.0_191]
at org.springframework.boot.SpringApplication.asUnmodifiableOrderedSet(SpringApplication.java:1313) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.getListeners(SpringApplication.java:1222) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.context.event.EventPublishingRunListener.contextLoaded(EventPublishingRunListener.java:85) ~[spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.SpringApplicationRunListeners.contextLoaded(SpringApplicationRunListeners.java:66) ~[spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.prepareContext(SpringApplication.java:384) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:325) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
at pl.piomin.services.employee.EmployeeApplication.main(EmployeeApplication.java:28) [classes!/:1.0-SNAPSHOT]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [employee-service-1.0-SNAPSHOT.jar:1.0-SNAPSHOT]
at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [employee-service-1.0-SNAPSHOT.jar:1.0-SNAPSHOT]
at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) [employee-service-1.0-SNAPSHOT.jar:1.0-SNAPSHOT]
at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) [employee-service-1.0-SNAPSHOT.jar:1.0-SNAPSHOT]
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Hi, how didyou run it? Which version of kubernetes you are using?
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Im getting same problem, how did you fix this?
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I didn’t fix it, because I haven’t got such an issue
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Great article!
The source repo link is wrong to Spring instead of k8s.
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Thanks 🙂 The source repo is ok – https://github.com/spring-cloud/spring-cloud-kubernetes
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I get same problem when deploying pretty much all the services,:
2019-03-01 08:25:47.001 INFO [-,,,] 1 — [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@4f4a7090: startup date [Fri Mar 01 08:25:46 GMT 2019]; root of context hierarchy
2019-03-01 08:25:47.351 INFO [-,,,] 1 — [ main] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 ‘javax.inject.Inject’ annotation found and supported for autowiring
2019-03-01 08:25:47.431 INFO [-,,,] 1 — [ main] trationDelegate$BeanPostProcessorChecker : Bean ‘org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration’ of type [org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration$$EnhancerBySpringCGLIB$$b5dc3fbb] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
. ____ _ __ _ _
/\\ / ___’_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | ‘_ | ‘_| | ‘_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
‘ |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.0.RELEASE)
2019-03-01 08:25:47 INFO [-,,,] The following profiles are active: kubernetes
2019-03-01 08:25:47 ERROR [-,,,] Application run failed
java.lang.AbstractMethodError: null
at org.springframework.core.OrderComparator.findOrder(OrderComparator.java:142) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.annotation.AnnotationAwareOrderComparator.findOrder(AnnotationAwareOrderComparator.java:65) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.getOrder(OrderComparator.java:125) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.getOrder(OrderComparator.java:113) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.doCompare(OrderComparator.java:82) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at org.springframework.core.OrderComparator.compare(OrderComparator.java:68) ~[spring-core-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
at java.util.TimSort.countRunAndMakeAscending(TimSort.java:360) ~[na:1.8.0_191]
at java.util.TimSort.sort(TimSort.java:220) ~[na:1.8.0_191]
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Hello
Do we still need to use the netflix api for ribbon and gateway? Or could we use spring cloud gateway and spring cloud load balancer?
Thanks
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Hello,
Although Spring Cloud Ribbon has been moved to the maintenance mode in the end of past year it is still the default client-side load balancer for all Spring Cloud projects. The development of Spring Cloud Loadbalancer is in progress, but I don’t think it has been finished yet. There is no any article about that, except my post on blog: https://piotrminkowski.wordpress.com/2019/04/05/the-future-of-spring-cloud-microservices-after-netflix-era/. If you need API gateway you can always use Kubernetes Ingress. In case you need Swagger API documentation you can probably use Spring Cloud Gateway. The only problem with that during writing this article was the lack of support for SpringFox Swagger project since Spring Cloud Gateway is based on asynchronous Netty server. However, I have already heard that this support has been implemented (I didn’t check it by myself).
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This is really a nice and informative article. I tried this example with Google Kubernetes Engine. When I am deploying mongodb on it, it is getting failed.
Error logs in mongo pod:
E QUERY [js] Error: couldn’t add user: Error preflighting normalization: U_STRINGPREP_PROHIBITED_ERROR :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
DB.prototype.createUser@src/mongo/shell/db.js:1491:15
@(shell):1:1
Can you help me with this?
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Hello, I didn’t try to deploy on GKE. But it’s the standard Mongo template
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Great article. Thanks a lot Piotr for putting this together making it easy for us to follow
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Un excellent article
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I think the kubernetes directory is missing from repo. I couldn’t find it on github and had to create it on my own.
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It is present: https://github.com/piomin/sample-spring-microservices-kubernetes/tree/master/kubernetes
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Hi Piotr,
I could make the pods, services and deployments running on my Windows 10 (enterprise) laptop. And I had added the IP – DNS mapping to C:\Windows\System32\drivers\etc\hosts. However for some reason it is not working as expected. So I have a couple of questions as below –
1> Do we need to set up this IP address and DNS mapping in the hosts file? If yes, which IP address should I map to “microservices.info” in the hosts file. Currently I mapped the one which is returned by IP Config.
2> I am using the Kubernetes engine that comes packed with Docker for Desktop (windows installer). I could not run Minikube (though I could install it ), because my laptop does not have sufficient memory. Can your project be deployed and tested, with this constraint ?
Sorry about my ignorance. Please help. Thank you!
Mandar
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Hi,
1. You need to map your VM with Kubernetes ip address. I don’t know what’s ip address when you use Docker Desktop (maybe localhost?), but for minikube it is returned by commany minikube ip.
2. Generally the applications require around 300-400 MB to start. There are 3 apps and Mongo, what gives us around 1.2 GB. Assuming it you can start minikube with minimum RAM requirement – 2gb. Of course you should also be able to run them on Kubernetes in Docker Desktop
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