Microservices Interview Questions and Answers

In this post we will take an overview of most important questions regarding the Microservices from basic to depth which will help you in cracking any difficult interview. So, there is no need to worry for your next interview test, because Codingcompiler is here to help you!

Microservices Interview Questions 

Q1) What is Microservices?
Q2)What Is Spring Cloud?
Q3) What Is Spring Boot?
Q4) How Do You Override a Spring Boot Project’s Default Properties?
Q5) List down the advantages of Microservices Architecture.

Q6) What do you know about Microservices?
Q7) What are the features of Microservices?
Q8) What do you understand by Microservices?
Q9) What are the main components of Microservices? 
Q10) What are the major principles of Microservices?

Microservices Interview Questions and Answers

Q) What is Microservices?

Microservices are a software development technique —a variant of the service-oriented architecture (SOA) structural style— that arranges an application as a collection of loosely coupled services. In a microservices architecture, services are fine-grained and the protocols are lightweight.

Q)What Is Spring Cloud?

 Spring Cloud, in microservices, is a system that provides integration with external systems. It is a short-lived framework that builds an application, fast. Being associated with the finite amount of data processing, it plays a very important role in microservice architectures.

For typical use cases, Spring Cloud provides the out of the box experiences and a sets of extensive features mentioned below:

  • Versioned and distributed configuration.
  • Discovery of service registration.
  • Service to service calls.
  • Routing.
  • Circuit breakers and load balancing.
  • Cluster state and leadership election.
  • Global locks and distributed messaging.

Q) What Is Spring Boot?

Spring boot is a major topic under the umbrella of microservices interview questions.

With the new functionalities that have been added, Spring got more complex. Whenever you are starting a new project it is mandatory to add a new build path or Maven dependencies. In short, you will need to do everything from scratch. Spring Boot is the solution that will help you to avoid all the code configurations. Explaining by a real time example is better while answering this common microservices interview question. If you are cooking a dish, the ingredients can be considered to be Spring. While Spring Boot is the completely cooked recipe.

Q) How Do You Override a Spring Boot Project’s Default Properties?

This can be done by specifying the properties in the application.properties file.

For example, in Spring MVC applications, you have to specify the suffix and prefix. This can be done by entering the properties mentioned below in the application.properties file.

For suffix – spring.mvc.view.suffix: .jsp

For prefix – spring.mvc.view.prefix: /WEB-INF/

Q) List down the advantages of Microservices Architecture.

A: Relatively small components/services

  1. Easier for a developer to understand
  2. Application starts faster
  3.   Speeds up deployments

Ease for deployment

  1. Each service can be deployed independently of other services

Easier to scale development

  1. Enables the ability to organize the development effort around multiple teams
  2. Each team can develop, deploy and scale their services independently of other teams

Improved fault isolation

  1. Any fault in one service will only impact that one — other services will continue to handle requests

Scale Independently 

  1. A microservice can scale independently using X-axis cloning and Z-axis partitioning based upon their need

No long-term commitment to any stack

Technology agnostic services

It enables rewriting the service using better languages and technologies

Microservices Interview Questions and Answers

Q) What do you know about Microservices?

  • Microservices, aka Microservice Architecture, is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.
  • In layman terms, you must have seen how bees build their honeycomb by aligning hexagonal wax cells.
  • They initially start with a small section using various materials and continue to build a large beehive out of it.
  • These cells form a pattern resulting in a strong structure which holds together a particular section of the beehive.
  • Here, each cell is independent of the other but it is also correlated with the other cells.
  • This means that damage to one cell does not damage the other cells, so, bees can reconstruct these cells without impacting the complete beehive.

Q) What are the features of Microservices?

  • Decoupling – Services within a system are largely decoupled. So the application as a whole can be easily built, altered, and scaled
  • Componentization – Microservices are treated as independent components that can be easily replaced and upgraded
  • Business Capabilities – Microservices are very simple and focus on a single capability
  • Autonomy – Developers and teams can work independently of each other, thus increasing speed
  • Continous Delivery – Allows frequent releases of software, through systematic automation of software creation, testing, and approval
  • Responsibility – Microservices do not focus on applications as projects. Instead, they treat applications as products for which they are responsible
  • Decentralized Governance – The focus is on using the right tool for the right job. That means there is no standardized pattern or any technology pattern. Developers have the freedom to choose the best useful tools to solve their problems
  • Agility – Microservices support agile development. Any new feature can be quickly developed and discarded again.

Q) What do you understand by Microservices?

A: Microservices or more appropriately Microservices Architecture is an SDLC approach based on which large applications are built as a collection of small functional modules. These functional modules are independently deployable, scalable, target specific business goals, and communicate with each other over standard protocols.  Such modules can also be implemented using different programming languages, have their databases, and deployed on different software environments. Each module here is minimal and complete.

Q) What are the main components of Microservices? 

A: The main components for a Microservice Architecture are:

  • Containers, Clustering, and Orchestration
  • IaC [Infrastructure as Code Conception] 
  • Cloud Infrastructure
  • API Gateway
  • Enterprise Service Bus
  • Service Delivery

Q) What are the fundamental characteristics of a Microservices Design?

  1. Domain Driven Design
  2. Hide Implementation Details
  3. Decentralization
  4. Failure Isolation
  5. Continuous Delivery through DevOps Culture

Frequently Asked Microservices Interview Questions and Answers for Beginners

Q) What Do You Mean By End-To-End Testing Of Microservices?

A: End to End testing validates all the processes in the workflow to check if everything is working properly as expected. It also ensures that the system works in a unified manner, thereby satisfying the business requirement.

Q) What are Microservices in Java?

A: Microservices are a form of service-oriented architecture style (one of the most important skills for Java developers) wherein applications are built as a collection of different smaller services rather than one whole app.

Q) What Are the Benefits of Microservices?

A: There are several benefits to using microservices. For one, because these smaller applications are not dependent on the same coding language, the developers can use the programming language that they are most familiar with. That helps developers come up with a program faster with lower costs and fewer bugs. The agility and low costs can also come from being able to reuse these smaller programs on other projects, making it more efficient.

Benefits of using microservices architecture?

Embracing microservices architecture brings many benefits compared to using monolith architecture in your application, including:

Autonomous Deployments

The decentralized teams working on individual microservices are mostly independent of each other, so changing a service does not require coordination with other teams. This can lead to significantly faster release cycles. It is very hard to achieve the same thing in a realistic monolithic application where a small change may require regression of the entire system.

Culture Shift

Microservices style of system architecture emphasizes on the culture of freedom, single responsibility, autonomy of teams, faster release iterations and technology diversification.

Technology Diversification

Unlike in monolithic applications, microservices are not bound to one technology stack (Java, .Net, Go, Erlang, Python, etc). Each team is free to choose a technology stack that is best suited for its requirements. For example, we are free to choose Java for a microservice, c++ for others and Go for another one.

DevOps Culture

The term comes from an abbreviated compound of “development” and “operations”. It is a culture that emphasizes effective communication and collaboration between product management, software development, and operations team. DevOps culture, if implemented correctly can lead to shorter development cycles and thus faster time to market.

Q) What Is Semantic Monitoring?

A: It combines monitoring of the entire application along with automated tests. The primary benefit of Semantic Monitoring is to find out the factors which are more profitable to your business.

Semantic monitoring along with service layer monitoring approaches monitoring of microservices from a business point of view. Once an issue is detected, they allow faster isolation and bug triaging, thereby reducing the main time required to repair. It triages the service layer and transaction to figure out the transactions affected by availability or poor performance.

Q) SOA vs. Microservices

A: “Wait a minute,” some of you may be murmuring over your morning coffee, “isn’t this just another name for SOA?”  Service-Oriented Architecture (SOA) sprung up during the first few years of this century, and microservice architecture (abbreviated by some as MSA) bears a number of similarities.  Traditional SOA, however, is a broader framework and can mean a wide variety of things. Some microservices advocates reject the SOA tag altogether, while others consider microservices to be simply an ideal, refined form of SOA.  In any event, we think there are clear enough differences to justify a distinct “microservice” concept (at least as a special form of SOA, as we’ll illustrate later).

The typical SOA model, for example, usually has more dependent ESBs, with microservices using faster messaging mechanisms.  SOA also focuses on imperative programming, whereas microservices architecture focuses on a responsive-actor programming style.  Moreover, SOA models tend to have an outsized relational database, while microservices frequently use NoSQL or micro-SQL databases (which can be connected to conventional databases).  But the real difference has to do with the architecture methods used to arrive at an integrated set of services in the first place.

Since everything changes in the digital world, agile development techniques that can keep up with the demands of software evolution are invaluable.  Most of the practices used in microservices architecture come from developers who have created software applications for large enterprise organizations, and who know that today’s end users expect dynamic yet consistent experiences across a wide range of devices.  Scalable, adaptable, modular, and quickly accessible cloud-based applications are in high demand. And this has led many developers to change their approach.

Advanced Microservices Interview Questions and Answers for Experienced

Q) What is cohesion in Microservices?

The whole point of microservices is to update or deploy one service while keeping other services intact. In a loosely coupled system, one service knows little about others. Sot this makes the key idea possible.

High cohesion means related logic is kept in one service. Otherwise, different services need to be chatty to each other across service boundary. This will hurt the overall performance.

Q) What are Microservices in AWS?

Microservices are an architectural and organizational approach to software development where software is composed of small independent services that communicate over well-defined APIs. These services are owned by small, self-contained teams.

Q) What is Spring Cloud in the realm of Microservices?

It is that kind of a feature in the realm of Microservices which would provide integration with the outside systems. It is also known as a short-lived Microservices framework that has the ability to build applications in a quick fashion. Moreover, it plays an important function in Microservices as it is associated with finite amounts of processing of data.

Q) : What are the different Microservices Design Patterns?

  • The different Microservices Design Patterns are –
  • Aggregator Microservice Design Pattern
  • API Gateway Design Pattern
  • Chain of Responsibility Design Pattern
  • Branch Microservice Design Pattern
  • Circuit Breaker Design Pattern
  • Asynchronous Messaging Design Pattern

Q) When should one consider microservice kind of architecture?

There are two cases.

Case i) If you already have a monolith application and it grows to an extent where there are problems in scaling or we are not able to reutilize the components/modules/services across different projects/platforms and there is a need to do so. As well as at the same time implementing new features is painful and more error-prone and it is difficult to scale further.

Case ii) For new applications where implementation has not started yet started, we can think of a business case to be efficiently implemented, which can be easily maintainable, testable and scalable in the future and might be used across other projects/products/platforms at the same time.

Q) How would you test microservice based architecture?

One should have unit and integration tests where all the functionality of a microservice can be tested. One should also have component based testing.

One should have contract tests to assert that the expectations by the client is not breaking. End-to-end test for the microservices, however, should only test the critical flows as these can be time-consuming. The tests can be from two sides, consumer-driven contract test and consumer-side contract test.

You can also leverage Command Query Responsibility Segregation to query multiple databases and get a combined view of persisted data.

Q) How does Microservice Architecture work?

  • Clients – Different users from various devices send requests.
  • Identity Providers – Authenticates user or clients identities and issues security tokens.
  • API Gateway – Handles client requests.
  • Static Content – Houses all the content of the system.
  • Management – Balances services on nodes and identifies failures.
  • Service Discovery – A guide to find the route of communication between microservices.
  • Content Delivery Networks – Distributed network of proxy servers and their data centers.
  • Remote Service – Enables the remote access information that resides on a network of IT devices.

Q) What is the difference between Monolithic, SOA and Microservices Architecture?

Monolithic Architecture is similar to a big container wherein all the software components of an application are assembled together and tightly packaged.

A Service-Oriented Architecture is a collection of services which communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity.

Microservice Architecture is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.

Q) What is a Gateway in microservice?

Customers don’t call on microservices directly, they go via the Gateway. The Gateway calls the microservices and returns the answer to the customer. The Gateway separates the customer’s microservices. It also offers authentication, logging, load balancing and so on.

Q) How do you monitor microservices?

The Spring Boot Controller is a decent instrument monitor statistics for individual microservices. However, it is hard to track them independently when you have multiple microservices. We could use opensource tools such as Prometheos, Kibana or Graphana for this purpose. Prometheous is a pull-based surveillance tool. It contains, shows and can activate notifications at certain intervals. Kibana or Grafana are dashboard instruments for data visualization and surveillance. As there are many dependencies in microservices, AppDynamics, Dynatrace and New Relics can be applied, which pull dependence between microservices.

Q) When designing Microservices, what are the best practices to follow?

These are the industry standards each programmer must follow in the design of Microservices:

  • Every microservice will often keep the information store separate.
  • When designing Microservices it is important that the code must be organised at the same intelligence level.
  • For each Microservice, a separate development should also be designed.
  • We should make sure that each development should be used in containers.
  • While designing the microservices it is always necessary to treat the server as stateless.

Q) Explain three types of Tests for Microservices

In Microservices architecture tests are categorized into three types:

  • We can conduct a particular test such as quality and unit tests at the lower level test. Such tests are fully automated.
  • We can conduct exploratory tests at the mid – level, such as stress tests and accessibility tests.
  • We can perform acceptance tests at the highest level that are mainly less numerical. It enables investors to understand the various software characteristics.

Top Microservices Interview Questions and Answers

Q) Shed light on the basic need of Microservices in today’s context of application development

In the field of software development, micro services are also recognised as a new pattern. It has taken on importance because it can increase efficiency and speed. It is also able to efficiently maintain software and services. Some people also call it a method and culture solution that gives greater business performance. It actually plays an extremely vital role in today’s software development, as it is able to be deployed efficiently in the production of a monolithic application.

Q) What is Coupling and Cohesion?

The coupling can be seen as the intensity calculation between the module reliance. A fine software design for Microservices often comprises of high cohesion and low coupling. When you are asked questions of microservices, it is important to remember that a structure of low coupling alongside high cohesion is an essential component in designing microservices. A service understands very little about another when it is loosely coupled. The services are therefore preserved. All pertaining reasoning can be maintained in a service in a higher level of cohesion. In other cases, the services will attempt and influence overall quality to interact with each other.

Q)Spring Cloud annotations and configuration?

@EnableServer annotation allows us to register microservices to the spring cloud.

@EnableDiscoveryClient annotation also allows us to query Discovery server to find miroservices.

Spring provide smart RestTemplate for service discovery and load balancing by using @LoadBalanced annotation with RestTemplate instance.

Q) How do you setup Service Discovery?

  • Spring Cloud support several ways to implement service discovery but for this I am going to use Eureka created by Netflix. Spring Cloud provide several annotation to make it use easy and hiding lots of complexity. 

Q) How do you access a RESTful microservice?

Load Balanced RestTemplate
If there are multiple RestTemplate you get the right one.
It can used to access multiple microservices

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