Most Asked Microservices Interview Questions & Answers – For Freshers & Experienced [2024]

Microservices are small, self-contained services that perform specific tasks. They are typically used to build large, complex applications. The advantages of microservices include increased scalability, improved reliability, and easier development and maintenance. 

Being familiar with microservices concepts and their implementation using Java and Spring Boot is important to secure a job in this sector. Read this blog discussing interview questions on microservices to sail through your microservices interview. 

Microservices Interview Questions and Answers

Microservices, or microservice architecture, is an asset to the latest software development methods like Agile and DevOps. Its ability to promptly deliver complex and large applications makes it a widely adopted architectural concept. This has resulted in a huge demand for professionals skilled in microservices. It is thus wise to prepare for microservices-based questions, ranging from the basics to technical areas, before applying for any software development-backed job role. Look at these microservices architecture interview questions curated both for freshers and experts to ace your upcoming interview.

Microservices Interview Questions and Answers for Freshers

Here is a list of interview questions on microservices that freshers must know to bolster their preparation.

1. What are microservices? How do they differ from monolithic architecture?

Microservices is an engineering style in which an application is broken down into small, loosely coupled services. These services are developed, deployed, and scaled independently. In contrast, a monolithic architecture tightly couples all components into a single unit.

Microservices offer several advantages over monolithic architectures, including better scalability, reliability, and faster development. Each microservice can be developed and deployed independently, making it easier to scale individual components as needed. Microservices are also more reliable because they are less likely to be affected by failures in other components. 

2. What are the advantages of using microservices?

The following are some of the advantages of using microservices:

• Increased scalability: Can be easily scaled up or down as needed, making them ideal for applications that experience fluctuating traffic.
• Improved reliability: More resilient to failure than monolithic applications because each service can be independently developed, tested, and deployed.
• Easier maintenance: Easier to maintain than monolithic applications because changes to one service do not affect other services.
• Increased flexibility: Can be easily reused in different applications, giving you greater flexibility in building your applications.

3. What are some common mistakes to avoid when designing microservices?

Some common mistakes to avoid when designing microservices include:

• Not having a clear architecture can lead to problems like difficulty scaling and maintaining your application. A clear architecture will help you design your microservices in a scalable, maintainable, and reliable way.
• Not using a microservices framework can make developing and managing your microservices difficult. A microservices framework can provide tools and libraries to help you develop and manage your microservices more easily.
• Not using a service mesh can lead to performance, reliability, and security issues. A service mesh can help you improve your microservices’ performance, reliability, and security by allowing them to communicate with each other.
• Not thoroughly testing your microservices can cause problems when deployed. Testing your microservices thoroughly will help you identify and fix any problems before they are deployed to production.
• Not monitoring your microservices may enable problems to slip through the cracks, which can affect the performance and reliability of your application. Monitoring your microservices will help you identify any problems so you can fix them quickly.

4. How do microservices communicate with each other?

Microservices can communicate via various protocols, including HTTP/HTTPS, REST, and messaging frameworks such as RabbitMQ or Apache Kafka. RESTful APIs are typically used for synchronous communication, while message queues are used for asynchronous communication between services.

5. How does Spring Cloud help in building microservices-based applications?
Spring Cloud is a set of tools that make it easier to develop, deploy, and manage microservices applications. It provides many features commonly used in microservices architectures, such as service discovery, load balancing, and fault tolerance. Spring Cloud also integrates with Spring Boot microservices, making it easy to start microservices development.

Here are some benefits of using Spring Cloud:

• Makes it easier to develop microservices applications.
• Provides several commonly used features in microservices architectures.
• Integrates with Spring Boot, making it easy to start microservices development.
• Is open-source and free to use.
• Well-documented and has a large community of users and contributors.

To learn more about microservices, programming languages and other aspects of software development, sign up for the Executive PG Programme in Full Stack Development from IIITB.

Microservices Interview Questions for Experienced

As with any interview, the questions asked of applicants with some experience differ from those of freshers. The questions are more technical, testing the interviewee’s practical knowledge. Here is a list of probable questions, including Spring Boot microservices interview questions that may come up in the interview:

1.Explain the role of a Service Library in a microservices architecture. How does Netflix Eureka help in this particular situation?

A service library is a crucial component in microservices that facilitates service discovery. It maintains a registry of all registered services and their locations, allowing services to find and communicate with each other dynamically.
Netflix Eureka is a popular implementation of the service library pattern in the Spring Boot ecosystem. It allows services to register with the library and query it to find other services during runtime.

2. In microservices, how do you ensure data consistency across multiple services in a transaction?

Ensuring data consistency in a distributed environment is a challenging task. One common approach is the Saga pattern, which breaks a transaction into smaller, atomic steps called “saga steps.” Each step corresponds to a local transaction within a service. If a step fails, compensating actions can be executed to roll back the changes made by previous steps. Tools like Apache Kafka can be used for event-based communication between services, supporting saga management.

3. Describe how API Gateways are used in microservices architecture? How can it help in addressing cross-cutting concerns?

An API Gateway is a single entry point for clients to interact with different microservices. It handles cross-cutting concerns such as authentication, rate limiting, caching, and request/response transformation. By centralising these concerns, API Gateways simplify the client-side code and reduce the complexity of microservices, allowing them to focus on business logic.

Check out our free technology courses to get an edge over the competition.

4. How would you execute logging and checking in a microservices-based application?

Logging and checking are indispensable for maintaining a healthy microservices environment. Tools like Spring Boot Actuator provide ready-to-use endpoints for monitoring and managing applications. Services can log events and metrics using libraries like Log4j or Slf4j, and aggregators like ELK stack (Elasticsearch, Logstash, and Kibana) can be used for unified logging and analysis.

5. Talk about the Circuit Breaker pattern concerning microservices. How can it improve system resilience?

The Circuit Breaker pattern is a way to prevent cascading failures in a microservices architecture. It works by monitoring the health of a service, and if it detects failures or abnormal behaviour, it opens the circuit. This means that subsequent requests to the failing service are not attempted, and a backup component or cached response is used instead. This approach improves system resilience by isolating the failure and preventing the system from becoming overwhelmed.

If you wish to build a career in cloud development and learn about microservices in-depth, join the Master of Science in Computer Science from LJMU by upGrad. Learn about the challenges of microservices, including communication between services and fault tolerance.

Technical Microservices Interview Questions

The rising adoption of microservices since its launch in 2011 is gradually leading to a surge in demand for professionals with fair technical knowledge of the architectural concept. The following list includes Java microservices interview questions that aspiring developers must know:

1. How would you deal with security in microservices architecture, especially while managing sensitive data?

Some techniques to secure microservices are:

• Authentication and authorisation: Appropriate authentication and authorisation mechanisms are implemented to control access to services and data.
• SSL/TLS: Communication between services is encrypted using SSL/TLS to prevent data interception attempts.
• Secret management: Sensitive data, such as database credentials, is stored in secure vaults like HashiCorp Vault or Kubernetes Secrets.
• OAuth 2.0: OAuth 2.0 is used for delegated authentication and secure service communication.
• Input validation and sanitisation: Input validation and data sanitisation are ensured to prevent injection attacks.

2. How do you handle distributed transactions in a microservices architecture?

Handling distributed transactions in a microservices architecture can be difficult due to the distributed nature of services. Traditional ACID transactions are unsuitable in this context as they may lead to two-phase commits and performance bottleneck issues. Instead, the Saga Pattern is commonly used.

The Saga Pattern breaks down a transaction into a sequence of smaller, localised transactions called saga steps. Each microservice involved in the transaction is responsible for its own local transaction and compensating actions if needed. If a step fails, compensating actions are executed to reverse the effects of the previously executed steps. Event-driven communication, such as a message broker like Apache Kafka, can help manage the sequence of saga steps and ensure that the overall transaction is eventually consistent.

Check Out upGrad’s Software Development Courses to upskill yourself.

3. How do you ensure data consistency and integrity in microservices architecture with eventual consistency?

In a microservices architecture, ensuring data consistency and integrity can be challenging due to the eventual consistency nature of distributed systems. Eventual consistency means that updates to data in one microservice may take some time to propagate to other services. To maintain data consistency, it is essential to follow certain practices:

• Idempotent operations: repeatable without changing results.
• Eventual consistency: data is consistent after a delay.
• CQRS pattern: separate read and write operations.
• Compensating actions: revert changes if a transaction fails.

It is crucial to carefully design the microservices and choose the appropriate level of consistency for each data interaction to balance data integrity and system performance.

Conclusion

Microservices architecture has transformed application development with scalability, reliability, and maintainability. However, it has challenges like communication, security, and debugging. Aspiring Java and Spring Boot developers should understand microservices concepts and best practices to build a successful career. 

upGrad’s Full Stack Software Development Bootcamp is perfect for professionals looking to upskill or transition from their current roles. The course offers project-based learning and helps prepare Java microservices interview questions to help aspirants secure their dream job.