20 Eureka Service Discovery Interview Questions and Answers

Eureka is a service discovery tool used in a distributed environment. It is responsible for maintaining a list of available services and their associated IP addresses. When a service is unavailable, Eureka will remove it from the list. In a job interview, you may be asked questions about how Eureka works and how it can be used in a microservices architecture. Answering these questions confidently can help you earn the position you want.

Eureka Service Discovery Interview Questions and Answers

Here are 20 commonly asked Eureka Service Discovery interview questions and answers to prepare you for your interview:

1. What is Eureka?

Eureka is a service discovery tool for distributed systems. It allows for the registration and discovery of services, and also provides some basic load balancing capabilities. Eureka is often used in conjunction with a load balancer such as HAProxy or NGINX.

2. What are some of the core components and features of Eureka?

Eureka has a number of core components, including a server, a client, and a registry. The server is responsible for maintaining a list of all the clients that are registered with it, as well as their current status. The client is responsible for sending periodic heartbeat messages to the server to let it know that it is still alive and available. The registry is a database that stores all the information about the clients that are registered with the server.

3. Can you explain what a service registry is in context with Eureka?

A service registry is a database that stores information about all of the services that are available on a network. This information can include the location of the service, the type of service, and any other relevant information. Eureka is a service discovery tool that uses this service registry to help clients find the services that they need.

4. How does Eureka work?

Eureka is a service discovery tool that allows for the registration and discovery of services. It uses a client-server architecture, with the server maintaining a registry of all the services that have been registered with it. When a client wants to discover a service, it contacts the server and requests a list of all the services that have been registered. The server then responds with a list of all the services that match the client’s request.

5. What’s your understanding of load balancing in the context of Eureka?

In Eureka, load balancing is handled by the client side load balancer. This is a software component that is responsible for distributing requests among the various Eureka instances that are registered with the service. The load balancer uses a variety of algorithms to determine how to distribute the requests, and can be configured to work with different types of applications.

6. What are the benefits of using Eureka?

Eureka is a great tool for service discovery because it is highly available and scalable. It is also easy to use, making it a good choice for many applications. Additionally, Eureka can be used to discover services that are running on different ports, which can be helpful in a microservices environment.

7. Where can I find more information about Eureka?

The best place to find more information about Eureka is on the Netflix website. Netflix has open-sourced the Eureka project, and provides a wealth of information on their website, including documentation, tutorials, and a mailing list.

8. What are the advantages of using Eureka over other services discovery tools like Zookeeper, etcd, or Consul?

Eureka has a number of advantages over other service discovery tools. First, it is very easy to set up and use. Second, it has built-in support for service registration and discovery, which makes it ideal for use in microservices architectures. Third, it is highly scalable and can handle large numbers of service instances with ease. Finally, it is very reliable and has been battle-tested in production environments.

9. Why do we need service discovery tools when software engineering already has built-in solutions for this problem?

Service discovery tools help to automate the process of finding and connecting to services, which can be particularly helpful in distributed systems where services are spread out across multiple machines. Additionally, service discovery tools can provide features such as monitoring and load balancing, which can be difficult to implement on your own.

10. How would you go about setting up Eureka server to run on port 8761?

You would need to set up a Eureka server to run on port 8761 by adding the following configuration to your application.yml file:

eureka:
instance:
hostname: localhost
port: 8761
client:
registerWithEureka: false
fetchRegistry: false

11. How do you make use of client-side load balancing in the context of Eureka?

Eureka uses client-side load balancing to route requests from clients to the appropriate service instance. When a client makes a request, Eureka will use a load balancing algorithm to determine which instance of the service to route the request to. This ensures that requests are evenly distributed across all available service instances, and that each instance is not overloaded with requests.

12. When should you avoid using Eureka?

Eureka is a great tool for service discovery, but it does have its limitations. One major limitation is that it can only be used with services that are written in Java. Additionally, it can be difficult to set up and configure, so if you are not familiar with it, it might not be the best tool for you.

13. Is it possible to register an existing Spring Boot application with Eureka server? If yes, then how?

Yes, it is possible to register an existing Spring Boot application with Eureka server. You will need to add the @EnableEurekaClient annotation to your Spring Boot application, and then configure your application to point to the Eureka server.

14. Does Eureka support multiple instances of the same microservice running simultaneously?

Yes, Eureka can support multiple instances of the same microservice running simultaneously. This is useful for things like blue/green deployments, where you can have two versions of a service running at the same time and route traffic to the appropriate version based on conditions.

15. What happens if there is a failure on one of the servers in the cluster?

If one of the servers in the cluster fails, then the Eureka service discovery will automatically remove that server from the list of available servers. This ensures that only healthy servers are used in the cluster, and that no requests are sent to a server that may be down.

16. What happens if a new instance of a particular microservice starts before being registered with the Eureka server?

If a new instance of a microservice starts before being registered with the Eureka server, then it will not be able to communicate with other microservices that are registered with the server. This can cause problems with the overall functionality of the microservice, as well as with the stability of the system as a whole.

17. What is the difference between local and remote regions on Eureka server?

The local region is the region where the Eureka server is deployed. The remote region is any other region that is not the local region.

18. What is the role of hystrix as part of Netflix OSS stack?

Hystrix is a library that helps to control the interactions between microservices, and prevent failures when one service is unavailable. It does this by providing a fallback option, and by monitoring the health of services.

19. Should every node be configured with a copy of the database used by the Eureka server?

No, every node does not need to be configured with a copy of the database used by the Eureka server. The Eureka server is responsible for maintaining a registry of all of the services that are available, and each node can query the server to find out what services are available and where they are located.

20. What is the best way to ensure that clients periodically renew their lease with the Eureka server?

The best way to ensure that clients periodically renew their lease with the Eureka server is to use a lease renewal scheduler. This scheduler will send a renew message to the Eureka server at the appropriate time, and the server will then update the lease accordingly. This ensures that the client’s lease is always up-to-date, and that the Eureka server always knows the client’s current status.