Download Spring Cloud Netflix Eureka Server Jar and Start Building Scalable and Resilient Microservices
Spring Cloud Netflix Eureka Server: A Guide for Beginners
If you are developing microservices-based applications with Spring Boot, you might have heard of Spring Cloud Netflix Eureka Server. It is a service registry that allows your microservices to discover and communicate with each other without hard-coding their locations. In this article, we will learn what Spring Cloud Netflix Eureka Server is, why we should use it, and how to set it up and use it in our projects.
What is Spring Cloud Netflix Eureka Server and why use it?
Service discovery is one of the key challenges in a microservices architecture. It refers to the process of finding the network location of a service provider that can satisfy a given request. For example, if you have a microservice that needs to call another microservice, how do you know where to send the request?
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One way to solve this problem is to use a service registry. A service registry is a central database that keeps track of all the available service instances and their locations. Each service instance registers itself with the service registry when it starts up, and unregisters itself when it shuts down. The service registry also monitors the health of the registered instances and removes any unhealthy ones. The clients can query the service registry to find out which instances are available for a given service, and then choose one of them based on some load-balancing algorithm.
Netflix Eureka is a popular implementation of service discovery pattern. It consists of two components: Eureka Server and Eureka Client. The Eureka Server is the service registry that holds the information about all registered services. The Eureka Client is a Java-based library that simplifies the interaction with the Eureka Server. It provides methods for registering, unregistering, querying, and updating service instances.
Spring Cloud Netflix provides integration between Spring Boot applications and Netflix OSS components, including Eureka. With Spring Cloud Netflix, you can quickly enable and configure common patterns inside your application using annotations and properties. For example, you can create a Eureka Server by adding @EnableEurekaServer annotation to your @SpringBootApplication class, or create a Eureka Client by adding @EnableEurekaClient annotation.
Some of the main features of Spring Cloud Netflix Eureka Server are:
It supports both peer-to-peer and client-server modes of communication between Eureka instances.
It provides a web-based dashboard that shows the status of all registered services.
It supports multiple zones and regions for high availability and fault tolerance.
It supports secure communication using SSL.
It integrates well with other Spring Cloud components, such as Ribbon, Hystrix, and Zuul.
How to set up a Eureka Server for service registry?
Setting up a Eureka Server is very easy with Spring Boot and Spring Cloud Netflix. Here are the steps you need to follow:
Create a new Spring Boot project using your preferred tool, such as Spring Initializr, and add the spring-cloud-starter-netflix-eureka-server dependency. This dependency will pull in all the required libraries and configuration for creating a Eureka Server.
Add the @EnableEurekaServer annotation to your main application class. This annotation will enable the Eureka Server functionality in your application.
Configure some properties for your Eureka Server in the application.properties or application.yml file. The most important ones are:
eureka.client.register-with-eureka: This property determines whether the Eureka Server should register itself with another Eureka Server. If you have only one Eureka Server, you should set this to false.
eureka.client.fetch-registry: This property determines whether the Eureka Server should fetch the registry information from another Eureka Server. If you have only one Eureka Server, you should set this to false.
eureka.instance.hostname: This property specifies the hostname of your Eureka Server. You can use localhost for testing purposes, but you should use a proper domain name for production environments.
eureka.server.enable-self-preservation: This property controls the self-preservation mode of the Eureka Server. In this mode, the Eureka Server will not remove any service instances that have not sent a heartbeat for a long time, assuming that there is a network problem. This can prevent accidental removal of healthy instances, but it can also cause stale data in the registry. You can set this to false to disable this mode.
Run your application and open in your browser. You should see the Eureka dashboard with no registered services.
How to register Eureka Clients with the Eureka Server?
Now that you have a running Eureka Server, you can register your microservices as Eureka Clients. Here are the steps you need to follow:
Create a new Spring Boot project for your microservice and add the spring-cloud-starter-netflix-eureka-client dependency. This dependency will pull in all the required libraries and configuration for creating a Eureka Client.
Add the @EnableEurekaClient annotation to your main application class. This annotation will enable the Eureka Client functionality in your application.
Configure some properties for your Eureka Client in the application.properties or application.yml file. The most important ones are:
eureka.client.service-url.defaultZone: This property specifies the URL of your Eureka Server. You can use for testing purposes, but you should use a proper URL for production environments.
eureka.instance.appname: This property specifies the name of your microservice. This name will be used to identify your service in the registry and by other clients.
eureka.instance.instance-id: This property specifies the unique identifier of your service instance. You can use $spring.application.name:$spring.application.instance_id:$random.value as a default value, which will generate a random ID for each instance.
Run your application and refresh in your browser. You should see your microservice registered with the Eureka Server.
How to use Spring Cloud Netflix Feign Client to consume Eureka Clients?
Now that you have registered your microservices with the Eureka Server, you can consume them using a REST client. However, instead of using the hard-coded URLs of the service instances, you can use their logical names and let the Eureka Client resolve them dynamically. This way, you can achieve load balancing, failover, and resilience in your communication.
spring-cloud-netflix-eureka-server maven dependency
spring-cloud-netflix-eureka-server health check
spring-cloud-netflix-eureka-server client registration
spring-cloud-netflix-eureka-server custom data
spring-cloud-netflix-eureka-server load balancing
spring-cloud-netflix-eureka-server peer awareness
spring-cloud-netflix-eureka-server self preservation
spring-cloud-netflix-eureka-server heartbeat interval
spring-cloud-netflix-eureka-server renewal threshold
spring-cloud-netflix-eureka-server eviction duration
spring-cloud-netflix-eureka-server registry fetch interval
spring-cloud-netflix-eureka-server initial instance info replication interval
spring-cloud-netflix-eureka-server backup registry impl
spring-cloud-netflix-eureka-server aws access id and secret key
spring-cloud-netflix-eureka-server aws region and zone names
spring-cloud-netflix-eureka-server aws cloud formation stack name and vpc id
spring-cloud-netflix-eureka-server aws binding strategy and auto scaling group name
spring-cloud-netflix-eureka-server aws route53 domain name and hosted zone id
spring-cloud-netflix-eureka-server aws eip binding retry count and interval time in seconds
spring-cloud-netflix-eureka-server enable self registration and query cache update interval ms
spring-cloud-netflix-eureka-server enable delta and disable delta property value for remote regions
spring-cloud-netflix-eureka-server remote region urls with region name and url pairs
spring-cloud-netflix-eureka-server remote region registry fetch interval in seconds
spring-cloud-netflix-eureka-server remote region trust store file name and password
spring-cloud-netflix-eureka-server should use dns for fetching service urls
spring-cloud-netflix-eureka-server should fetch registry for remote regions
spring-cloud-netflix-eureka-server should filter only up instances
spring-cloud-netflix-eureka-server should on demand update status change
spring-cloud-netflix-eureka-server should enforce registration at startup