eureka.client.register-with-eureka |
Whether to register the Eureka Server itself as a service. |
false |
eureka.client.fetch-registry |
Whether to fetch the registry information from other Eureka Servers. |
false |
eureka.client.service-url.defaultZone |
The URL of the default zone where the Eureka Server is located. |
http://localhost:8761/eureka/ |
eureka.instance.hostname |
The hostname of the Eureka Server instance. |
The IP address of the instance. |
eureka.server.enable-self-preservation |
Whether to enable the self-preservation mode, which prevents the server from expiring services when there is a network partition. |
true |
eureka.server.eviction-interval-timer-in-ms |
The interval in milliseconds to check for expired services and remove them from the registry. |
60000 |
eureka.server.renewal-percent-threshold |
The percentage of renewals from services that are expected in a given period. If the renewals drop below this threshold, the self-preservation mode is triggered. |
0.85 |
How to Register and Discover Services with Eureka Server
Registering Services with Eureka Server
To register your microservices with Eureka Server, you need to add the @EnableDiscoveryClient annotation to your main application class. For example:
import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; @SpringBootApplication @EnableDiscoveryClient public class ProductServiceApplication { public static void main(String[] args) { SpringApplication.run(ProductServiceApplication.class, args); } }
You also need to add the Eureka Client dependency to your project. You can use the Spring Initializr website or the following Maven or Gradle snippets:
<!-- Maven --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> // Gradle implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-client'
Finally, you need to specify the Eureka Server URL in your application.properties or application.yml file. For example:
# application.properties eureka.client.service-url.defaultZone=http://localhost:8761/eureka/ # application.yml eureka: client: service-url: defaultZone: http://localhost:8761/eureka/
Now, you can run your microservice as a normal Spring Boot application and it will automatically register itself with Eureka Server. You can verify this by checking the Eureka Server dashboard and seeing your service name and instance ID.
Discovering Services with Eureka Server
To discover other services registered with Eureka Server, you can use the DiscoveryClient interface provided by Spring Cloud. You can inject it into your service class and use its methods to get the information about other services. For example:
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.cloud.client.ServiceInstance; import org.springframework.cloud.client.discovery.DiscoveryClient; import org.springframework.stereotype.Service; @Service public class ProductService { @Autowired private DiscoveryClient discoveryClient; public String getInventoryServiceUrl() { List<ServiceInstance> instances = discoveryClient.getInstances("inventory-service"); if (instances != null && !instances.isEmpty()) { return instances.get(0).getUri().toString(); } return null; } }
You can also use the @LoadBalanced annotation on a RestTemplate bean to enable client-side load balancing and use the service name instead of the URL when making REST calls. For example:
import org.springframework.cloud.client.loadbalancer.LoadBalanced; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.web.client.RestTemplate; @Configuration public class RestConfig { @Bean @LoadBalanced public RestTemplate restTemplate() { return new RestTemplate(); } }
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.web.client.RestTemplate; @Service public class ProductService { @Autowired private RestTemplate restTemplate; public int getInventory(String productId) { return restTemplate.getForObject("http://inventory-service/inventory/" + productId, Integer.class); } }
Alternatives to Eureka Server
Some Popular Alternatives to Eureka Server
Eureka Server is not the only option for service discovery. There are other tools that offer similar or different features and capabilities. Some of the popular alternatives are:
- Zookeeper: A distributed coordination service that provides service registry, configuration management, leader election, and more.
- Consul: A distributed service mesh that provides service discovery, configuration, health checks, encryption, and more.
- Etcd: A distributed key-value store that provides service discovery, configuration, locking, and more.
- Nacos: A dynamic service discovery, configuration, and service management platform that supports cloud-native applications.
- Kubernetes: A container orchestration system that provides service discovery, load balancing, configuration, health checks, and more.
How to Choose the Best Service Discovery Tool for Your NeedsHow to Choose the Best Service Discovery Tool for Your Needs
There is no one-size-fits-all solution for service discovery. The best tool for your needs depends on various factors, such as:
- The size and complexity of your system: How many services do you have? How often do they change? How dynamic and scalable is your system?
- The features and requirements of your system: What kind of service discovery do you need? Do you need configuration, health checks, encryption, or other features? Do you have any performance, reliability, or security requirements?
- The compatibility and integration of your system: What technologies and frameworks are you using? How well do they integrate with the service discovery tool? Do you need to migrate from an existing tool or system?
- The cost and maintenance of your system: How much time and money are you willing to spend on setting up and running the service discovery tool? How easy is it to monitor, troubleshoot, and update the tool?
To help you choose the best service discovery tool for your needs, you can use the following steps:
- List down your service discovery needs and priorities.
- Research and compare the features, pros, and cons of different service discovery tools.
- Test and evaluate the tools that meet your criteria.
- Select the tool that best suits your system and budget.
Conclusion
In this article, we have shown you how to download and use Eureka Server for service discovery. We have also explained what Eureka Server is, why you need it, and what are some alternatives to it.
Eureka Server is a simple and resilient service registry that integrates well with other Netflix OSS and Spring Cloud components. It allows you to register and discover microservices in a distributed system with minimal configuration and dependencies.
However, Eureka Server is not the only option for service discovery. There are other tools that offer similar or different features and capabilities. You should choose the best service discovery tool for your needs based on various factors such as size, complexity, features, requirements, compatibility, integration, cost, and maintenance of your system.
We hope this article has helped you learn more about Eureka Server and service discovery. If you have any questions or feedback, please feel free to leave a comment below.
FAQs
What is the difference between Eureka Server and Eureka Client?
Eureka Server is the service registry that maintains the information about all the registered services. Eureka Client is the library that enables the services to register themselves with Eureka Server and discover other services through it.
How can I secure my Eureka Server?
You can secure your Eureka Server by using Spring Security or Spring Cloud Security. You can configure authentication and authorization rules for accessing the Eureka Server dashboard or API. You can also enable SSL/TLS encryption for the communication between Eureka Server and clients.
How can I scale my Eureka Server?
You can scale your Eureka Server by running multiple instances of it in different zones or regions. You can configure them to communicate with each other using peer-to-peer replication or a central registry. You can also use a load balancer or a DNS server to route the requests to the available Eureka Servers.
How can I monitor my Eureka Server?
You can monitor your Eureka Server by using Spring Boot Actuator or Spring Cloud Netflix Turbine. You can expose various metrics and endpoints for checking the health, status, configuration, and performance of your Eureka Server. You can also use external tools such as Prometheus or Grafana to visualize and analyze the data.
How can I troubleshoot my Eureka Server?
You can troubleshoot your Eureka Server by using Spring Boot DevTools or Spring Cloud Netflix Hystrix. You can enable logging, tracing, debugging, and testing features for your Eureka Server. You can also use external tools such as Zipkin or Sleuth to track and trace the requests across your microservices.
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