Java Microservices Interview Questions for Experienced

21. How to Register Java Microservices Using Netflix Eureka?

The Eureka is the Netflix service discovery, consists of a discovery server and a client. The server can be configured and deployed to maximize performance, with each server copying the status of registered services to others. To Register and Discover Microservices Using Netflix Eureka we have to develop one Service Discovery and one Microservice.

• Developing Microservice or Eureka Client
• Developing Service Discovery or Eureka Server

For more details please refer to this article: How to Register Microservices Using Netflix Eureka?

22. What is Client Side Service Discovery in Java Microservices and Provide Some Examples of It?

In microservices, Service discovery refers to the process of dynamically locating and connecting to available services within a distributed system.

• In a microservice system, applications perform multiple tasks and that are composed of many independently deployable services.
• Service discovery is critical to facilitate communication between these different services.
• If we put Service Discovery in client side then we called it as Client Side Service Discovery.

Example:

• Netflix Eureka
• Zookeeper
• Consul

For more details please refer to this article: Client Side Service Discovery in Microservices

23. What is Server Side Service Discovery in Java Microservices and Provide Some Examples of It?

In microservices, Service discovery refers to the process of dynamically locating and connecting to available services within a distributed system.

• In a microservice system, applications perform multiple tasks and that are composed of many independently deployable services.
• Service discovery is critical to facilitate communication between these different services.
• If we put Service Discovery in server side then we called it as Server Side Service Discovery.

Example:

• NGNIX
• AWS ELB

For more details please refer to this article: Server Side Service Discovery in Microservices

24. Why Use Spring Cloud for Microservices Development?

Spring Cloud is a project under which we have many sub-projects. We can solve all these problems with those sub-projects.

• Spring Cloud Config Server
• Service registration and discovery using Eureka
• Spring Cloud LoadBalancer
• resilience4j-ratelimiter
• Circuit Breakers Pattern

For more details please refer to this article: Why Use Spring Cloud for Microservices Development?

25. Explain 5 Major Challenges and Solutions of Java Spring Boot Microservices Architecture.

There are 5 challenges are mentioned below with solutions that we might face while developing microservices applications.

• Challenge 1: Service Configuration Management
  • Solution: Spring Cloud Config Server centralizes configuration management for microservices.
• Challenge 2: Service Discovery and Registration
  • Solution: Eureka enables dynamic service discovery and registration.
• Challenge 3: Load Balancing Across Microservices
  • Solution: Spring Cloud LoadBalancer distributes traffic evenly among microservice instances.
• Challenge 4: Resilience and Fault Tolerance
  • Solution: resilience4j-ratelimiter implements rate limiting to maintain stability under heavy load.
• Challenge 5: Handling Failures and Circuit Breakers
  • Solution: Circuit Breaker pattern with tools like Hystrix provides fault isolation and fallback mechanisms.

For more details please refer to this article: 5 Major Challenges and Solutions of Microservices Architecture

26. Tell Some Major Reasons to Choose Spring Boot For Microservices Development.

Here are some major reason to Choose Spring Boot For Microservices Development.

• Embedded Server
• Support Load Balancer
• Auto Configuration
• Minimal Code using Annotations
• Loose Coupling
• Dependency Management
• Open Source

For more details please refer to this article: Major Reasons to Choose Spring Boot For Microservices Development

27. What is Circuit Breaker Pattern in Java Microservices?

Circuit Breaker pattern in microservices follows fault-tolerance mechanism. It monitors and controls the interaction between different services. It dynamically manages service availability by temporarily canceling requests for failed services, prevents system overloading, and ensures graceful degradation in distributed environments. Circuit Breaker pattern typically operates in three basic states: Closed, Open, and Half-Open.

Here are some Characteristics of Circuit Breaker pattern:

• Fault Tolerance
• Resilience
• Monitoring
• Failure Isolation
• Fallback Mechanism
• Automatic Recovery

28. Explain Different Deployment Techniques to Deploy Java Microservices.

There are different ways to deploy Microservices. Some of them are mentioned below:

• Single Machine, Multiple Services: Buy a server and run microservices as services.
• Multiple Machines, Multiple Services: When application exceeds the capacity of the server, we can upgrade the server by scaling up (Add more Servers).
• Containerization: Each microservices runs independently by enabling flexibility and scaling as per demand.
• Orchestrators: It distributes the workload of a container over a group of servers. (Ex: Kubernetes)
• Serverless Deployment: Processes or containers use cloud to run code on demand.

29. What is the Main role of Docker in Microservices and How to deploy microservices in Docker?

The main role of Docker in microservices is to provide containerization, which allows each microservice with its dependencies to coordinate with the runtime environment, ensuring stability in unique environments.

Steps to deploy microservices in Docker:

• Step 1: Containerize each microservice by creating a Dockerfile specifying the application’s dependencies and runtime configuration.
• Step 2: Build Docker images for each microservice using the docker build command.
• Step 3: Push the built Docker images to a Docker registry such as Docker Hub or a private registry.
• Step 4: Create Docker Compose or Kubernetes manifests defining the configuration for deploying and orchestrating the microservices.
• Step 5: Deploy the Dockerized microservices using Docker Compose or Kubernetes by running docker-compose up or applying the Kubernetes manifests respectively.
• Step 6: Monitor and manage the deployed microservices using Docker CLI commands or Kubernetes dashboard.

30. How to Deploy Java Spring Boot Microservices in AWS?

To deploy our microservices application in AWS (Amazon Web Services), we need to follow the below steps.

• Step 1: In the first step, open the AWS Management Console and then go to EC2.
• Step 2: After that, click on the Load Balancers and create a new Application Load Balancer. Also, create a new target group associated with that load balancer. Then define the target group targets (ECS instances) and health checks.
• Step 3: Now, in AWS Management Console, go to ECS and create a new ECS cluster.
• Step 4: Then choose the networking options and click on next.
  • Configure the cluster give name to the cluster.
  • Then create ECS Task and click on the repository.
  • Now, configure the repository and make sure it is private.
  • Lastly, create the Task Definitions.
• Step 5: Now update the ECS Task.

For more details please refer to this article: Deploy a Microservices Architecture with AWS

Microservices, also called Microservices Architecture, is a software development approach that involves building large applications as a collection of small functional modules. This architectural approach is widely adopted due to its ease of maintenance and faster development process.

Microservices with the Spring Boot framework break down complex applications into smaller services, loosely coupled services, each focusing on a specific business capability. This architecture promotes agility, scalability, and resilience, leveraging technologies like Docker, Kubernetes, and RESTful APIs for seamless communication and deployment in distributed environments.

Here, in this Java Microservices Interview Questions we have gathered a list of the Top 30 Java Microservices Interview Questions with Answers that are commonly asked in recent interviews. Whether you are a fresher or an experienced professional with 2, 5, 8, or 10 years of experience, going through these microservices interview questions will help you prepare for your upcoming technical interviews and increase your chances of succeeding.