Top 20 Frequently Asked Microservices Interview Questions

The rise of the digital era has brought technical advancement, which simplifies the lifestyle of human beings. Several applications were launched in this phase, and many more are on the way to provide comfort to customers and enhance business. Developing applications have many architectural patterns, each with built-in services that rely on APIs. With this relayed process making changes in a single service in an application becomes a tidy job, so here comes microservices. 

Microservices is an application development method in which developers develop one application by integrating multiple tiny individual services. Here, each service can be deployed independently by a docker on a cluster of machines, which helps developers focus on the service that is high in demand or needs improvisation.

As a developer, I have applied this method and have been very satisfied with the result. I’m sharing some microservices interview questions and answers that a company expects you to know. The knowledge of the questions can showcase your professional skills on the job. These are 20 microservices interview questions and answers frequently asked by an interviewer.

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20 Microservices Interview Questions and Answers

1] What are Microservices?

Ofcourse you can expect what is microservices in microservices interview questions. Microservices is an architectural pattern that helps developers build applications. These applications are loosely connected to multiple services, and each service can be developed and deployed independently. Let us understand this concept with an example, suppose you developed an e-commerce app and found that the wishlist section consumes more memory. To fix this issue, you can solely work on this particular section rather than covering all services, so this architectural style is known as Microservices. 

2] Can You Explain The Working Process of Microservices?

An application comprises several modules, including a database, logging, and business logic, and making a simple update or scaling any function becomes a complex task. So, microservices have come into play by replacing service-oriented architecture (SOA), which enables the developer to work on an individual function seamlessly. 

Every function in an application resides in a container. Docker further deploys the containers into the supported OS, which scales and manages the functions and allows you to interact with them. Thus, such a task is completely automated, reducing time and work and giving the utmost result. 

To explain the working methodology during microservices interview questions, you can describe the components of microservices architecture design, which includes resilience, decentralized, data separation, API, and automation. Covering these sections will help the interviewer to know your microservices knowledge. 

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3] Can you define the key components involved in the Microservices?

Microservices comprise several components, such as Containers, Load balancers, Circuit breakers, API Gateway, Cloud Infrastructure, Continuous Deployment, Service monitoring, Service orchestration, and  Decentralization. An experienced panel may seek an answer to this question and expect this in microservices interview questions. So be ready with the above answers and, if possible, explain each component.

4] Explain the pros and cons of Microservices.

In this section, I strongly believe that you should cover the prime benefits of microservices in application development and share some insights that companies are facing due to their presence.

Pros

• Microservices enable the team to work independently on a service of a high-demand application. This feature helps management determine the cost of scaling a service.

• Microservices support the CI/CD concept, which enables developers to experiment with new ideas and remove services that are not in use.

• Microservices provide a fault-isolation feature, which helps developers fix a service error without stopping an application. This means that working in an isolated service and troubleshooting the issue in such a service is easier than finding and fixing the problem in a complete set of services. 

• It comes with a range of programming stacks, including languages, databases, and many more, helping developers create a function based on the stacks, which is favorable for such a service.  

Cons

• Microservices architecture provides a multi-cloud environment to the services so that a developer can work on each service independently. But, during the process, each service has to communicate with the API, and they face security threats due to the lack of a security layer.

• Microservices enable services to run on multiple hosts, resulting in the collection of log messages. If an issue arises in any function, it is very hard for developers to find the logs from those hosts to fix the problem.

• In microservices, each service can be developed and deployed independently, but at the final stage, they are aggregated to form an application. This means services have some interconnection, and if any changes are made in a service, then it will be tough for a developer to track the effects on other services.

5]  Does Docker have any role in the Microservices?

Yes, it has a very important role because microservices are cloud-native architectures in which Dockers deploy the containers that contain functions to the respective OS (mostly Linux). It also helps scale the functions to fulfill demands quickly. Since Docker is idle and runs separately from the main code base, microservices can be launched quickly. Automation and integration are a part of Docker usage, making it essential for microservices. Still, it has wide roles to play in the microservice architecture of applications.

6] What is the role of API Gateway in Microservices?

Each service microservices interacts with each other through an API, which is the source that allows clients to interact with the services. As per the microservices working procedure, when a client interacts with an application, the respective queries are sent by the API to the concerned services, and thereafter, the API gathers all the responses from the services and delivers them to the clients. API gateway also plays a role in authentication, and control access, to avoid any threats.  

7] Which law is microservices architecture based on?

Microservices architecture is based on Conway’s law, which states that the internal structure of an organization should be directly proportional to the software architecture. This means that the architecture of microservices can be assigned based on the team’s expertise. For instance, if there are two teams whose areas of expertise are different, then the architecture of microservices will be designed based on the expertise of each team so that they can perform the task well. 

8] What is the difference between service registry and service discovery in microservices?

These two play an important role in maintaining communication between the services. A service registry is like a starting point, where the microservice registers itself by providing essential information, such as API, network location, and more. At the same time, service discovery pushes the service registry to locate a network location for effective communication with another service. 

9] How do Microservices and Serverless Architecture differ from each other?

In a microservices architecture, the application is divided into multiple services, and each service can be developed and deployed independently. Each service is a function that resides in a container and is further deployed by a docker into the cluster of machines. Such an infrastructure is provided by an organization or a cloud service provider. Another interesting fact about microservices is the scaling factor that is done by a developer manually. 

In the case of serverless architecture, developers just need to write code to create a function, and the rest of the jobs are done by the cloud service provider. In this architecture, developers don’t have to take the stress of infrastructure as everything is provided by a cloud service provider. Still, he/she needs to pay the money based on the instances of the functions. Moreover, the scaling process is automatic, and developers don’t have to do anything. The interesting part of serverless architecture is that the functions are triggered based on the events. For instance, the triggering events in Amazon ECS are Amazon S3, CloudWatch, and more.

10] Can you explain Command Query Responsibility Segregation (CQRS) and its execution process in Microservices?

Command Query Responsibility Segregation is a software architecture pattern that ensures that the reading and writing codes are separated to simplify data logic. In microservices, the writing part of data in CQRS handles commands, and the reading part is responsible for handling queries. Application logic is used to separates the commands and queries in the microservices. 

11] Explain Domain-driven Design (DDD), and is there any relation between DDD and Microservices?

Every business needs software that gives users a clear picture of the business so that they can build trust in the products/services provided by the businesses. Domain-driven design helps such businesses a lot because it brings a developer and business niche expert into the same platform to design an application/software that matches all the business criteria.  

DDD's goal is to create an application, and thus, this method follows some principles that align with microservices. For instance, one such principle is Bounded text, an application is divided into multiple functions, each function being developed independently. The same case applies to applications that use the microservice architecture.

12] What’s your understanding about Blue-Green Deployment?

Blue-Green deployment is a strategy developers apply to roll back the application effectively with zero downtime. In a broader sense, a developer creates two identical environments for an application where one, i.e., blue, denotes the current version of an application and the one more, i.e., green, signifies the latest version, which is under the testing process. So, this deployment process enables the developers to switch the traffic from blue to green to increase the application availability, and once the green environment is ready for users, then entire traffic will be diverted from blue to green.

13] How is Auto-scaling performed in Microservices?

Auto-scaling is an automatic process where the demand for a specific service of an application is met, container-retaining functions are docked by a docker, and compute resources are provided by a cloud provider based on the demand. So, this type of auto-scaling is performed in microservices to enhance the application’s performance.

14] List some tools that are used in Microservices architecture.

AWS Lambda, API Fortress, Prometheus, Docker, Kong, and Kubernetes are popular tools for building software/applications using a microservices architecture.

15] What is the Saga Design Pattern in Microservices?

I recommend that you start explaining distributed transactions before answering these types of microservices interview questions. In microservices, a distributed transaction is a type of transaction that has a separate database and is spread across various networks. 

A saga design pattern manages these distributed transactions. It isolates the transaction known as the saga, and thereafter, Saga Orchestration comes into play, triggering the Saga to perform in the microservices. The performance of these Sagas is monitored, and if all the distributed transactions perform well, then Saga Orchestration will mark them as completed successfully. 

16] Can you differentiate between SAGA and CQRS design patterns in Microservices architecture?

Saga and CQRS are two different design patterns used in Microservices. In the former, the SAGA is responsible for managing distributed transactions, while the CQRS separates the data based on command and query.

17] Can you explain the bulkhead pattern in Microservices?

The bulkhead pattern is commonly used in application design. This pattern enhances the system's resilience by enabling developers to isolate a non-functional service from a pool so that the rest of the services can perform smoothly. It is named after the watertight compartments used on ships.

18] What are the common types of microservices architectures that are widely used?

Three types of microservices architectures are widely used in creating applications: domain, integration, and unit-of-work microservices.

19] Can you list out the best-supported frameworks for Microservices?

The microservices framework is a very important utility that consists of tools and structures that help developers build an application. So, the most popular microservices frameworks are:

• Express.js

• Micronaut

• Eclipse MicroProfile

• FastAPI

• Lagom

• Spring Boot

20] Can you tell me about the 3C’s of Microservices?

It is one of the most prominent microservices interview questions that an interviewer asks. To answer this question, you should start with a microservices architecture and define the 3C’s that are widely used among the developers: Componentizing, Collaborate, and connecting. The componentizing refers to the degree of freedom of modules during deployment, and it’s completely independent, whereas Collaborate signifies the synchronization of services and ensures that they work together. The last one, i.e., Connect, ensures the services are connected to the API.

Also Read: What Are The Microservices Architecture?

Conclusion

The above-mentioned microservices interview questions and answers will help you find a developer or DevOps job easily. While mentioning the microservices interview questions, I tried to pour down all the relevant questions asked in the interviews. However, you should also focus on the fundamentals of Microservices architecture and how it replaced the Monolithic software architecture pattern.

Understanding the concept of microservices, design patterns, and frameworks will help you adapt this new development environment. However, you may need to dive deeper into this segment. In that case, you should opt for DevOps Certification, and this certification will give you an in-depth knowledge of Agile principles, and more that will help you develop quality software using a microservices architecture effectively.