Spring Cloud Starter Eureka Server Jar Download
If you are developing microservices with Spring Boot and Spring Cloud, you might have heard of Spring Cloud Netflix Eureka. It is a service discovery solution that allows you to register and discover your microservices without hard-coding their locations. In this article, we will show you how to download and install the spring-cloud-starter-eureka-server jar file, which is the dependency you need to set up a Eureka Server in your project. We will also show you how to register and discover services with Eureka Server, and how to access and monitor its dashboard.
spring-cloud-starter-eureka-server jar download
Introduction
Spring Cloud Netflix Eureka is a part of the Spring Cloud Netflix project, which provides integrations with Netflix OSS (Open Source Software) components. Eureka is one of these components, and it is responsible for service discovery.
Service discovery is a key feature in a microservices architecture, where you have multiple independent services that need to communicate with each other. Instead of hard-coding the hostnames and ports of these services, you can use a service registry, where each service can register itself with its location and metadata. Then, other services can query the registry to find and consume the registered services.
Eureka Server is the service registry component that you can set up in your project. It has the following features and benefits:
It is easy to use and configure with Spring Boot and Spring Cloud annotations and properties.
It supports both client-side and server-side load balancing, which means that each client can cache the registry information locally and use a load-balancing algorithm to choose the best service instance.
It is resilient to failures, as it can handle network errors, service outages, and registry replication issues.
It provides a web interface where you can view the registered services and their instances, as well as their health and status.
It integrates well with other Spring Cloud Netflix components, such as Zuul (a routing and filtering proxy), Hystrix (a circuit breaker and fallback mechanism), Ribbon (a client-side load balancer), and Feign (a declarative REST client).
How to Download and Install Eureka Server Jar
To set up a Eureka Server in your project, you need to download and install the spring-cloud-starter-eureka-server jar file, which is the dependency that contains all the required libraries and configurations. Here are the steps you need to follow:
Prerequisites and Dependencies
To use Eureka Server, you need to have the following prerequisites:
spring-cloud-starter-eureka-server maven dependency
spring-cloud-starter-eureka-server gradle dependency
spring-cloud-starter-eureka-server example
spring-cloud-starter-eureka-server configuration
spring-cloud-starter-eureka-server tutorial
spring-cloud-starter-eureka-server properties
spring-cloud-starter-eureka-server version
spring-cloud-starter-eureka-server github
spring-cloud-starter-eureka-server annotation
spring-cloud-starter-eureka-server port
spring-cloud-starter-eureka-server application.yml
spring-cloud-starter-eureka-server bootstrap.yml
spring-cloud-starter-eureka-server docker
spring-cloud-starter-eureka-server enable self preservation
spring-cloud-starter-eureka-server authentication
spring-cloud-starter-eureka-server ssl
spring-cloud-starter-eureka-server cluster
spring-cloud-starter-eureka-server peer awareness
spring-cloud-starter-eureka-server health check
spring-cloud-starter-eureka-server logging
spring-cloud-starter-eureka-server actuator
spring-cloud-starter-eureka-server swagger
spring-cloud-starter-eureka-server zuul
spring-cloud-starter-eureka-server ribbon
spring-cloud-starter-eureka-server hystrix
spring-cloud-starter-eureka-server feign
spring-cloud-starter-eureka-server load balancing
spring-cloud-starter-eureka-server retry mechanism
spring-cloud-starter-eureka-server fallback strategy
spring-cloud-starter-eureka-server circuit breaker
spring-cloud-starter-eureka-server cache refresh interval
spring-cloud-starter-eureka-server heartbeat interval
spring-cloud-starter-eureka-server registration interval
spring-cloud-starter-eureka-server eviction interval
spring-cloud-starter-eureka-server lease duration
spring-cloud-starter-eureka-server lease renewal interval
spring-cloud-starter-eureka-server lease expiration duration ratio
spring-cloud-starter-eureka-server prefer ip address over hostname
spring-cloud-starter-eureka-server prefer same zone eureka servers
spring-cloud-starter-eureka-server use dns for fetching service urls
spring-cloud-starter-eureka-server service url zone mapping
spring-cloud-starter-eureka-server default zone
spring-cloud-starter-eureka-server client region
spring-cloud-starter-eureka-server client filter only up instances
spring-cloud-starter-eureka-server client fetch registry
spring-cloud-starter-eureka-server client register with eureka
Java 8 or later
Maven or Gradle as your build tool
Spring Boot 2.x as your application frameworkTo use Eureka Server, you also need to add the following dependency to your pom.xml file if you are using Maven, or to your build.gradle file if you are using Gradle:
```xml
org.springframework.cloud
spring-cloud-starter-eureka-server
3.0.4
``` ```gradle implementation 'org.springframework.cloud:spring-cloud-starter-eureka-server:3.0.4' ``` You can find the latest version of the dependency on the .
Spring Initializr
A convenient way to generate a project template with the Eureka Server dependency is to use , which is a web-based tool that allows you to create and configure Spring Boot applications. You can follow these steps to use Spring Initializr:
Go to the and fill in the basic information, such as the project name, group ID, artifact ID, packaging, and Java version.
Select Spring Boot 2.x as the Spring Boot version.
Under the dependencies section, search for and select Eureka Server.
Click on the Generate button to download a zip file containing the project template.
Extract the zip file and open the project in your preferred IDE (Integrated Development Environment).
Eureka Server Configuration
After you have created and opened the project, you need to enable and configure Eureka Server in your Spring Boot application. You can do this by following these steps:
In the main class of your application, add the @EnableEurekaServer annotation above the class declaration. This annotation tells Spring Boot that this application is a Eureka Server and should start as one.
```java import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; @SpringBootApplication @EnableEurekaServer public class EurekaServerApplication public static void main(String[] args) SpringApplication.run(EurekaServerApplication.class, args); ``` In the application.properties file (or application.yml if you prefer YAML format), add some properties to configure Eureka Server. For example, you can set the server port, the application name, and whether to register itself with other Eureka Servers (if you have more than one). Here is an example of some basic properties:
```properties server.port=8761 spring.application.name=eureka-server eureka.client.register-with-eureka=false eureka.client.fetch-registry=false ``` You can find more properties and their descriptions on the .
Save and run your application. You should see some logs indicating that Eureka Server is up and running on port 8761.
How to Register and Discover Services with Eureka Server
Now that you have set up a Eureka Server in your project, you can use it to register and discover your microservices. To do this, you need to add the Eureka Client dependency to your microservice applications, and configure them to register with and query from Eureka Server. Here are the steps you need to follow:
Eureka Client Dependency and Annotation
To use Eureka Client in your microservice applications, you need to add the following dependency to your pom.xml file if you are using Maven, or to your build.gradle file if you are using Gradle:
```xml
org.springframework.cloud
spring-cloud-starter-eureka-client
3.0.4
``` ```gradle implementation 'org.springframework.cloud:spring-cloud-starter-eureka-client:3.0.4' ``` You can find the latest version of the dependency on the .
In addition, you need to add the @EnableEurekaClient annotation above the main class of your microservice application. This annotation tells Spring Boot that this application is a Eureka Client and should communicate with Eureka Server.
```java import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; @SpringBootApplication @EnableEurekaClient public class MicroserviceApplication public static void main(String[] args) SpringApplication.run(MicroserviceApplication.class, args); ``` Eureka Client Configuration and Registration
After you have added the Eureka Client dependency and annotation to your microservice application, you need to configure some properties to register it with Eureka Server. You can do this by adding some properties to your application.properties file (or application.yml if you prefer YAML format). For example, you can set the application name, the Eureka Server URL, and the instance ID. Here is an example of some basic properties:
```properties spring.application.name=microservice eureka.client.service-url.defaultZone= eureka.instance.instance-id=$spring.application.name:$random.value ``` You can find more properties and their descriptions on the .
Save and run your microservice application. You should see some logs indicating that it has registered with Eureka Server successfully.
Feign Client Configuration and Consumption
To consume a registered service from another microservice, you can use Spring Cloud Netflix Feign Client, which is a declarative REST client that simplifies the HTTP communication. To use Feign Client in your microservice application, you need to add the following dependency to your pom.xml file if you are using Maven, or to your build.gradle file if you are using Gradle:
```xml
org.springframework.cloud
spring-cloud-starter-openfeign
3.0.4
``` ```gradle implementation 'org.springframework.cloud:spring-cloud-starter-openfeign:3.0.4' ``` You can find the latest version of the dependency on the .
In addition, you need to add the @EnableFeignClients annotation above the main class of your microservice application. This annotation tells Spring Boot that this application can use Feign Clients to consume registered services.
```java import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.cloud.openfeign.EnableFeignClients; @SpringBootApplication @EnableEurekaClient @EnableFeignClients public class MicroserviceApplication public static void main(String[] args) SpringApplication.run(MicroserviceApplication.class, args); ``` To create a Feign Client for a registered service, you need to define an interface and annotate it with @FeignClient. The annotation takes the name of the service as a parameter, and optionally some configuration properties. Then, you can declare methods in the interface that correspond to the REST endpoints of the service, and annotate them with Spring MVC annotations, such as @GetMapping, @PostMapping, etc. Here is an example of a Feign Client for a service named hello-service that has a GET endpoint at /hello:
```java import org.springframework.cloud.openfeign.FeignClient; import org.springframework.web.bind.annotation.GetMapping; @FeignClient(name = "hello-service") public interface HelloServiceClient @GetMapping("/hello") String hello(); ``` To use the Feign Client in your microservice application, you can simply inject it as a bean and call its methods. For example, you can create a REST controller that uses the Feign Client to consume the hello-service:
```java import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class HelloController private final HelloServiceClient helloServiceClient; public HelloController(HelloServiceClient helloServiceClient) this.helloServiceClient = helloServiceClient; @GetMapping("/consume") public String consume() return helloServiceClient.hello(); ``` How to Access and Monitor Eureka Server Dashboard
Eureka Server provides a web interface where you can view the registered services and their instances, as well as their health and status. To access the dashboard, you can simply open your browser and go to the URL of your Eureka Server application. For example, if if your Eureka Server is running on port 8761 on your local machine, you can go to You should see a page like this:
The dashboard shows the following information:
The application name and the status of the Eureka Server.
The general info section, which displays the current time, environment, profiles, and server port.
The instances currently registered with Eureka section, which lists the names and URLs of the registered services and their instances. You can click on each instance to see more details, such as its metadata, status, and health check URL.
Spring Boot Actuator Endpoints
To monitor the health and status of your Eureka Server application, you can use Spring Boot Actuator, which is a sub-project of Spring Boot that provides production-ready features, such as metrics, audits, and health checks. To use Spring Boot Actuator in your Eureka Server application, you need to add the following dependency to your pom.xml file if you are using Maven, or to your build.gradle file if you are using Gradle:
```xml
org.springframework.boot
spring-boot-starter-actuator
2.5.6
``` ```gradle implementation 'org.springframework.boot:spring-boot-starter-actuator:2.5.6' ``` You can find the latest version of the dependency on the .
After you have added the dependency, you can access various endpoints that provide information about your Eureka Server application. For example, you can go to /actuator/health to see the health status of your application, or to /actuator/info to see some basic information about your application. You can also customize and configure the endpoints according to your needs. You can find more details and examples on the .
Conclusion
In this article, we have shown you how to download and install the spring-cloud-starter-eureka-server jar file, which is the dependency you need to set up a Eureka Server in your project. We have also shown you how to register and discover services with Eureka Server, and how to access and monitor its dashboard.
Eureka Server is a service discovery solution that allows you to register and discover your microservices without hard-coding their locations. It has many features and benefits, such as easy configuration, load balancing, resilience, web interface, and integration with other Spring Cloud Netflix components.
If you want to learn more about Eureka Server and how to use it in your microservices architecture, you can check out these links and resources:
FAQs
What are some alternatives to Eureka Server for service discovery?
Some alternatives to Eureka Server for service discovery are:
, which is a distributed service mesh that provides service discovery, configuration, and coordination.
, which is a centralized service for maintaining configuration information, naming, and providing distributed synchronization.
, which is a distributed key-value store that provides service discovery and configuration management.
, which is a container orchestration system that provides service discovery and load balancing for microservices.
How to enable security and authentication for Eureka Server?
To enable security and authentication for Eureka Server, you can use Spring Security, which is a framework that provides comprehensive security features for Spring applications. To use Spring Security in your Eureka Server application, you need to add the following dependency to your pom.xml file if you are using Maven, or to your build.gradle file if you are using Gradle:
```xml ```xml
org.springframework.boot
spring-boot-starter-security
2.5.6
``` ```gradle implementation 'org.springframework.boot:spring-boot-starter-security:2.5.6' ``` You can find the latest version of the dependency on the .
After you have added the dependency, you can configure some properties and beans to enable basic authentication for your Eureka Server application. For example, you can set the username and password in your application.properties file (or application.yml if you prefer YAML format):
```properties spring.security.user.name=admin spring.security.user.password=secret ``` You can also create a configuration class that extends WebSecurityConfigurerAdapter and overrides the configure method to allow Eureka Clients to bypass the authentication. Here is an example of such a class:
```java import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; import org.springframework.context.annotation.Configuration; import org.springframework.core.Ordered; import org.springframework.core.annotation.Order; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter; @Configuration @EnableEurekaServer @Order(Ordered.HIGHEST_PRECEDENCE) public class SecurityConfig extends WebSecurityConfigurerAdapter @Override protected void configure(HttpSecurity http) throws Exception http.csrf().disable() .authorizeRequests() .antMatchers("/eureka/").hasRole("ADMIN") .anyRequest().authenticated() .and() .httpBasic(); ``` You can find more details and examples on how to enable security and authentication for Eureka Server on the .
How to handle failures and fallbacks with Eureka Server?
To handle failures and fallbacks with Eureka Server, you can use Spring Cloud Netflix Hystrix, which is a circuit breaker and fallback mechanism that provides resilience and fault tolerance for microservices. To use Hystrix in your microservice applications, you need to add the following dependency to your pom.xml file if you are using Maven, or to your build.gradle file if you are using Gradle:
```xml
org.springframework.cloud
spring-cloud-starter-netflix-hystrix
2.2.9.RELEASE
``` ```gradle implementation 'org.springframework.cloud:spring-cloud-starter-netflix-hystrix:2.2.9.RELEASE' ``` You can find the latest version of the dependency on the .
After you have added the dependency, you need to enable Hystrix in your microservice application by adding the @EnableCircuitBreaker annotation above the main class of your application. This annotation tells Spring Boot that this application can use Hystrix to handle failures and fallbacks.
```java import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.cloud.netflix.hystrix.EnableCircuitBreaker; @SpringBootApplication @EnableEurekaClient @EnableCircuitBreaker public class MicroserviceApplication public static void main(String[] args) SpringApplication.run(MicroserviceApplication.class, args); ``` To use Hystrix in your Feign Client, you need to add the fallback attribute to the @FeignClient annotation, and specify a class that implements the Feign Client interface and provides fallback methods for each endpoint. Here is an example of a fallback class for the hello-service Feign Client:
```java import org.springframework.stereotype.Component; @Component public class HelloServiceFallback implements HelloServiceClient @Override public String hello() return "Hello service is unavailable"; ``` To use Hystrix in your REST controller, you need to add the @HystrixCommand annotation to each method that calls a Feign Client, and specify a fallback method that returns a default value or an error message. Here is an example of a REST controller that uses Hystrix:
```java import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class HelloController private final HelloServiceClient helloServiceClient; public HelloController(HelloServiceClient helloServiceClient) this.helloServiceClient = helloServiceClient; @GetMapping("/consume") @HystrixCommand(fallbackMethod = "consumeFallback") public String consume() return helloServiceClient.hello(); public String consumeFallback() return "Failed to consume hello service"; ``` You can find more details and examples on how to use Hystrix with Eureka Server on the .
How to scale and cluster Eureka Server for high availability?
To scale and cluster Eureka Server for high availability, you can run multiple instances of Eureka Server and configure them to communicate with each other. This way, if one instance goes down, the other instances can still serve the requests and maintain the registry information. To do this, you need to follow these steps:
Create a configuration file for each Eureka Server instance, and give them different names and ports. For example, you can create two files named application-peer1.properties and application-peer2.properties, and set the following properties:
```properties # application-peer1.properties server.port=8761 spring.application.name=eureka-server eureka.client.register-with-eureka=true eureka.client.fetch-registry=true eureka.client.service-url.defaultZone= eureka.instance.instance-id=$spring.application.name:$random.value # application-peer2.properties server.port=8762 spring.application.name=eureka-server eureka.client.register-with-eureka=true eureka.client.fetch-registry=true eureka.client.service-url.defaultZone= eureka.instance.instance-id=$spring.application.name:$random.value ``` The properties above tell each Eureka Server instance to register with and fetch from the other instance, creating a peer-to-peer relationship.
Run each Eureka Server instance with the corresponding configuration file. For example, you can use the following commands:
```bash java -jar eureka-server.jar --spring.profiles.active=peer1 java -jar eureka-server.jar --spring.profiles.active=peer2 ``` You should see some logs indicating that each Eureka Server instance has registered with and replicated from the other instance.
Register your microservice applications with both Eureka Server instances by adding both URLs to the eureka.client.service-url.defaultZone property in your application.properties file (or application.yml if you prefer YAML format). For example:
```properties eureka.client.service-url.defaultZone= ``` This way, your microservice applications can register with and query from both Eureka Server instances, ensuring high availability.
How to customize and extend Eureka Server functionality?
To customize and extend Eureka Server functionality, you can use some of the following options:
You can use Eureka Server Events, which are events that are triggered by various actions on Eureka Server, such as registry updates, status changes, and replication events. You can create listeners for these events and implement custom logic or behavior. For example, you can create a listener that sends an email notification when a service goes down. You can find more details and examples on how to use Eureka Server Events on the .
You can use Eureka Server Filters, which are filters that intercept the requests and responses between Eureka Server and its clients. You can create custom filters to modify or enhance the communication process. For example, you can create a filter that adds authentication headers to the requests or responses. You can find more details and examples on how to use Eureka Server Filters on the .
You can use Eureka Server Extensions, which are extensions that provide additional features or integrations for Eureka Server. You can create your own extensions or use some of the existing ones, such as .
I hope you have enjoyed reading this article and learned something new about Spring Cloud Starter Eureka 44f88ac181