Top 20 Microservices Interview Questions and Answers

Getting ready for a job interview that’s all about microservices? Well, you’re in the right place. We’ve gathered the top 20 microservices interview questions and paired them with detailed answers to help you shine in that interview room. Whether you’re a seasoned pro in the world of microservices or just starting out, these questions and answers are here to boost your confidence and knowledge. Let’s dive in and get you all set to impress your potential employers with your microservices expertise.

Top 20 Microservices Interview Questions

Q1) What are Microservices?

Microservices, also known as Microservices Architecture, is a software development approach that involves constructing complex applications by assembling smaller, independent functional modules. Think of it as building a large, intricate system from smaller, self-contained building blocks.

For instance, imagine a modern e-commerce platform. Instead of creating one monolithic application to handle everything from product listings to payments, you can use microservices. Each function, like product catalog, shopping cart, user authentication, and payment processing, becomes a separate microservice. They work together as a cohesive unit, with each microservice responsible for its specific task.

This approach offers benefits such as flexibility, scalability, and ease of maintenance. If one microservice needs an update or experiences issues, it can be modified or fixed without affecting the entire system. It’s like having a toolkit of specialized tools that can be swapped in or out as needed, making software development more efficient and adaptable.

Q2) What are the main features of Microservices?

Decoupling: Modules are independent and do not rely on each other.

Componentization: Applications are divided into small, manageable components.

Business Capabilities: Modules correspond to specific business functions.

Autonomy: Each module can function independently.

Continuous Delivery(CI/CD): Frequent updates and releases are possible.

Responsibility: Each module is responsible for its functionality.

Decentralized Governance: Decision-making is distributed across modules.

Agility: Adaptability and responsiveness to changes are key attributes.

Q3) What are the key parts of Microservices?

Microservices rely on various elements to work effectively. Some of the main components include:

• Containers, Clustering, and Orchestration: These tools help manage and organize microservices within a software environment.

• Infrastructure as Code (IaC): IaC involves using code to automate and control infrastructure setup and configuration.

• Cloud Infrastructure: Many microservices are hosted on cloud platforms, which provide the necessary computing resources.

• API Gateway: An API Gateway acts as a central entry point for various microservices, making it easier for them to communicate with each other.

• Enterprise Service Bus: This component facilitates efficient communication and integration between different microservices and applications.

• Service Delivery: Ensuring that microservices are delivered effectively to end-users and seamlessly integrated into the software system.

These components work together to support the operation of microservices and enhance the scalability and flexibility of a software system.

Q4) Explain the working of microservices?

Microservices Architecture:

Client Request: The process begins when a client, such as a web browser or mobile app, sends a request to the application. This request could be anything from fetching data to performing specific tasks.

API Gateway: The client’s request is initially intercepted by the API Gateway, acting as the application’s point of entry. Think of it as the first stop for incoming requests.

Service Discovery (Eureka Server): To find the right microservice to fulfill the request, the API Gateway checks in with the Eureka Server. This server plays a crucial role by maintaining a directory of where different microservices are located.

Routing: With information from the Eureka Server in hand, the API Gateway directs the request to the specific microservice that’s best suited to handle it. This ensures that each request goes to the right place.

Circuit Breaker: Inside the microservice, a Circuit Breaker is at work, keeping an eye on the request and the microservice’s performance. If the microservice faces issues or becomes unresponsive, the Circuit Breaker can temporarily halt additional requests to prevent further problems.

Microservice Handling: The designated microservice takes the reins, processing the client’s request, and interacting with databases or other services as needed.

Response Generation: After processing the request, the microservice generates a response. This response might include requested data, an acknowledgment, or the results of the task requested by the client.

Ribbon Load Balancing: On the client’s side, Ribbon comes into play. It’s responsible for balancing the load when multiple instances of the microservice are available. Ribbon ensures that the client connects to the most responsive instance, enhancing performance and providing redundancy.

API Gateway Response: The response generated by the microservice is sent back to the API Gateway.

Client Response: Finally, the API Gateway returns the response to the client. The client then receives and displays this response. It could be the requested information or the outcome of a task, allowing the user to interact with the application seamlessly.

Q5) What are the differences between Monolithic, SOA and Microservices Architecture?

Q6: What is  Service Orchestration and Service Choreography in Microservices?

Service orchestration and service choreography are two different approaches for managing the dance of microservices. Here’s how they groove:

• Service Orchestration: This is like having a conductor in an orchestra. There’s a central component that’s the boss, controlling and coordinating the movements of all microservices. It’s a tightly organized performance with everything in sync.
• Service Choreography: Think of this as a group of dancers who know the steps and dance together without a choreographer. In service choreography, microservices collaborate directly with each other, no central controller in sight. It’s a bit more like a jam session, where each service has its own rhythm.
• Comparison: Service orchestration offers a more controlled and well-coordinated dance, where every step is planned. Service choreography, on the other hand, is like a dance-off where individual services have the freedom to show their moves. It’s more flexible, but it can get a bit wild.

Q7) What is the role of an actuator in Spring Boot?

In Spring Boot, an actuator is a project that offers RESTful web services to access the real-time status and information about an application running in a production environment. It allows you to monitor and manage the usage of the application without the need for extensive coding or manual configuration. Actuators provide valuable insights into the application’s health, metrics, and various operational aspects, making it easier to maintain and troubleshoot applications in a production environment.

Q8) How to Customize Default Properties in Spring Boot Projects?

Customizing default properties in a Spring Boot project, including database properties, is achieved by specifying these settings in the application.properties file. Here’s an example that explains this concept without plagiarism:

Example: Database Configuration

Imagine you have a Spring Boot application that connects to a database. To tailor the database connection to your needs, you can define the following properties in the application.properties file:

spring.datasource.url = jdbc:mysql://localhost:3306/bd-name
spring.datasource.username = user-name
spring.datasource.password = password

By setting these properties in the application.properties file, you can easily adjust the database configuration of your Spring Boot application. This flexibility allows you to adapt your project to different database environments or specific requirements without the need for extensive code modifications

Q9) What is Cohesion and Coupling in Software Design?

Cohesion refers to the relationship between the parts or elements within a module. It measures how well these elements work together to serve a common purpose. When a module exhibits high cohesion, its elements collaborate efficiently to perform a specific function, and they do so without requiring constant communication with other modules. In essence, high cohesion signifies that a module is finely tuned for a specific task, which, in turn, enhances the overall functionality of that module.

For example, consider a module in a word-processing application that handles text formatting. It exhibits high cohesion by focusing solely on tasks like font styling, paragraph alignment, and spacing adjustments without being entangled in unrelated tasks.

Coupling signifies the relationship between different software modules, like Modules A and B. It assesses how much one module relies on or interacts with another. Coupling can be categorized into three main types: highly coupled (high dependency), loosely coupled, and uncoupled. The most favorable form of coupling is loose coupling, which is often achieved through well-defined interfaces. In a loosely coupled system, modules maintain a degree of independence and can be modified or replaced with minimal disruption to other modules.

For instance, think of an e-commerce application where the product catalog module and the shopping cart module are loosely coupled. They communicate through a clear interface, allowing each to function independently. This facilitates future changes or upgrades to either module without causing significant disturbances in the overall system.

In summary, cohesion and coupling are fundamental principles in software design that influence how modules are organized and interact within a software system. High cohesion and loose coupling are typically sought after because they lead to more efficient, maintainable, and adaptable software systems.

Q10) What Defines Microservice Design?

Microservice design is guided by a set of core principles that distinguish it from traditional monolithic architectures:

• Business-Centric Approach: Microservices are organized around specific business capabilities or functions. Each microservice is responsible for a well-defined task, ensuring alignment with the organization’s core business objectives.
• Product-Oriented Perspective: Unlike traditional projects, microservices are treated as ongoing products. They undergo continuous development, maintenance, and improvement to remain adaptable to evolving business needs.
• Effective Messaging Frameworks: Microservices rely on robust messaging frameworks to facilitate seamless communication. These frameworks enable microservices to exchange data and coordinate tasks efficiently.
• Decentralized Governance: Microservices advocate decentralized governance, granting autonomy to each microservice team. This decentralization accelerates development and decision-making processes.
• Distributed Data Management: Data management in microservices is typically decentralized, with each microservice managing its data store. This approach fosters data isolation, scalability, and independence.
• Automation-Driven Infrastructure: Automation plays a pivotal role in microservices. Infrastructure provisioning, scaling, and maintenance are automated, reducing manual effort and minimizing downtime.
• Resilience as a Design Principle: Microservices are designed with the expectation of failures. Consequently, they prioritize resilience. When one microservice encounters issues, it should not disrupt the entire system, ensuring uninterrupted service availability.

These principles collectively contribute to the agility, scalability, and fault tolerance that make microservices a popular choice in modern software development. They reflect a strategic shift towards building software systems that are more responsive to the dynamic demands of today’s businesses.

Q11: What’s the Purpose of Spring Cloud Config and How Does It Work?

let’s simplify this for a clear understanding:

Purpose: Spring Cloud Config is like the command center for configuration properties in microservices. Its main job is to make sure all the configurations are well-organized, consistent, and easy to access.

How It Works:

• Version-Controlled Repository: All your configuration info is stored in a special place that keeps a history of changes. Think of it as a well-organized filing cabinet for configurations.
• Configuration Server: Inside Spring Cloud Config, there’s a designated server that takes care of your configuration data. It’s like the trustworthy guard of your valuable information.
• Dynamic and Centralized: The cool part is that microservices can request their configuration details from this server on the spot, while they’re running. This means any changes or updates to the configurations are instantly shared with all the microservices. It’s like having a super-efficient communication channel for all your configurations.

Q12) How Do Independent Microservices Communicate?

Picture a world of microservices, each minding its own business. Yet, they need to talk to each other, and they do it quite ingeniously:

• HTTP/REST with JSON or Binary Protocols: It’s like sending letters or emails. Microservices make requests to others, and they respond. They speak a common language, often in formats like JSON or more compact binary codes. This works well when one service needs specific information or tasks from another.
• Websockets for Streaming: For those real-time conversations, microservices use Websockets. Think of it as talking on the phone, but not just in words – they can share data continuously. It’s ideal for things like live chats, streaming updates, or interactive applications.
• Message Brokers: These are like message relay stations. Services send messages to a central point (the broker), and it ensures messages get to the right recipients. There are different types of brokers, each specialized for specific communication scenarios. Apache Kafka, for instance, is like the express courier for high-throughput data.
• Backend as a Service (BaaS): This is the “hands-free” option. Microservices can use platforms like Space Cloud, which handle a bunch of behind-the-scenes tasks. It’s like hiring someone to take care of your chores. BaaS platforms can manage databases, handle authentication, and even run serverless functions.

In this interconnected world, microservices pick the best way to chat based on what they need to say. It’s all about keeping them independent yet harmoniously communicating in the vast landscape of microservices.

Q13) What is Domain-Driven Design (DDD)?

Domain-Driven Design, often abbreviated as DDD, is an approach to software development that centers on a few key principles:

• Focus on the Core Domain and Domain Logic: DDD places a strong emphasis on understanding and honing in on the most critical and valuable aspects of a project, which is often referred to as the “core domain.” This is where the primary business or problem-solving logic resides. DDD aims to ensure that the software accurately represents and serves this core domain.
• Analyze Domain Models for Complex Designs: DDD involves in-depth analysis of the domain models. By doing so, it seeks to uncover intricate designs and structures within the domain that may not be immediately apparent. This analysis helps in creating a software design that faithfully mirrors the complexity and nuances of the real-world domain.
• Continuous Collaboration with Domain Experts: DDD encourages regular and close collaboration between software development teams and domain experts. These domain experts are individuals who possess in-depth knowledge of the problem domain (the industry or field in which the software will be used). By working together, they refine the application model, ensuring it effectively addresses emerging issues and aligns with the evolving domain requirements.

In essence, Domain-Driven Design is a holistic approach that promotes a deep understanding of the problem domain, leading to software solutions that are more accurate, relevant, and adaptable to the ever-changing needs of the domain they serve.

Q14). What is OAuth?

Think of OAuth as the key to the world of one-click logins. It’s what allows you to use your Facebook or Google account to access various websites and apps without creating new usernames and passwords.

Here’s the magic:

• No More New Accounts: Imagine you stumble upon a cool new app, and it asks you to sign up. With OAuth, you can skip that part. Instead, you click “Log in with Facebook” or another platform you trust.
• Sharing Just What’s Needed: You don’t have to share your Facebook password with the app. Instead, the app asks Facebook, “Is this person who they claim to be?” Facebook says, “Yep, it’s them!” and you’re in.
• Secure and Convenient: OAuth makes logging in more secure because you’re not giving out your password to every app you use. It’s like showing your ID card to get into a party without revealing all your personal info.

So, next time you see the option to log in with Google or some other platform, you’ll know that OAuth is working behind the scenes to make your life simpler and safer on the internet.

 Q15) Why Reports and Dashboards Matter in Microservices?

Reports and dashboards play a pivotal role in the world of microservices for several key reasons:

• Resource Roadmap: Imagine reports and dashboards as your detailed map of the microservices landscape. They show you which microservices handle specific tasks and resources. It’s like having a GPS for your system’s functionality.
• Change Confidence: When changes happen (and they do in software), reports and dashboards step in as your security net. They tell you exactly which services might be impacted. Think of it as a warning system that prevents surprises.
• Instant Documentation: Forget digging through files or searching for the latest documents. Reports and dashboards are your instant, always-up-to-date documentation. Need info on a specific service? It’s just a click away.
• Version Control: In the microservices world, keeping tabs on different component versions is a bit like tracking your app updates. Reports and dashboards help you stay on top of what’s running where and if any part needs an upgrade.
• Quality Check: They’re your quality control inspectors. They help you assess how mature and compliant your services are. It’s like checking the quality of ingredients before cooking a meal – you want everything to be up to the mark.

So, reports and dashboards are your trustworthy companions, helping you navigate the intricacies of microservices, ensuring you’re in control and making informed decisions in this dynamic software world.

Q16) What are Reactive Extensions in Microservices?

Reactive Extensions, or Rx, is a design approach within microservices that coordinates multiple service calls and combines their results into a single response. These calls can be blocking or non-blocking, synchronous or asynchronous. In the context of distributed systems, Rx operates in a manner distinct from traditional workflows.

Q17) Types of Tests Commonly Used in Microservices?

Testing in the world of microservices can be quite intricate due to the interplay of multiple services. To manage this complexity, tests are categorized based on their level of focus:

• Unit Tests: These tests zoom in on the smallest building blocks of microservices – individual functions or methods. They validate that each function performs as expected in isolation.
• Component Tests: At this level, multiple functions or components within a single microservice are tested together. Component tests ensure that the internal workings of a microservice function harmoniously.
• Integration Tests: Integration tests go further by examining how different microservices collaborate. They validate that when multiple microservices interact, the system behaves as anticipated.
• Contract Tests: These tests check the agreements or contracts between microservices. They ensure that the communication between services adheres to predefined standards, preventing unintended disruptions.
• End-to-End (E2E) Tests: E2E tests assess the entire application’s functionality, simulating user journeys. They validate that all microservices work cohesively to provide the desired user experience.
• Load and Performance Tests: These tests evaluate how microservices perform under varying loads. They help identify bottlenecks and performance issues to ensure the system can handle real-world demands.
• Security Tests: Security tests scrutinize the microservices for vulnerabilities and ensure data protection measures are effective.
• Usability Tests: Usability tests assess the user-friendliness and accessibility of the microservices. They focus on the overall user experience.

Q18) What are Containers in Microservices?

Containers are a powerful solution for managing microservices. They excel in efficiently allocating and sharing resources, making them the preferred choice for developing and deploying microservice-based applications. Here’s the essence of containers in the world of microservices:

• Resource Allocation: Containers excel in efficiently distributing computing resources. They ensure each microservice has the right amount of CPU, memory, and storage to function optimally.
• Isolation: Containers create a secure boundary for each microservice. They operate independently, preventing conflicts or interference between services, which is crucial in microservices architecture.
• Portability: Containers package microservices and their dependencies into a single, portable unit. This means you can develop a microservice on your local machine and deploy it in various environments, ensuring consistency.
• Efficient Scaling: Containers make scaling microservices a breeze. You can replicate and deploy containers as needed, responding quickly to changing workloads.
• Simplified Management: Container orchestration platforms like Kubernetes provide centralized management for deploying, scaling, and monitoring microservices in a containerized environment.

Q19) The Core Role of Docker in Microservices?

• Containerizing Applications: Docker acts as a container environment where you can place your microservices. It not only packages the microservice itself but also all the necessary components it relies on to function seamlessly. These bundled packages are aptly called “Docker containers.”
• Streamlined Management: With Docker containers, managing microservices becomes straightforward. You can effortlessly start, stop, or move them around, akin to organizing neatly labeled boxes for easy transport.
• Resource Efficiency: Docker ensures that each microservice receives the appropriate amount of computing resources, like CPU and memory. This ensures that they operate efficiently without monopolizing or underutilizing system resources.
• Consistency: Docker fosters uniformity across different stages, such as development, testing, and production. No longer will you hear the excuse, “It worked on my machine.” Docker guarantees consistency, a valuable asset in the world of microservices.

Q20): What are tools used to aggregate microservices log files?

In the world of microservices, managing log files can be a bit of a juggling act. To simplify this essential task, here are some reliable tools at your disposal:

• ELK Stack (Elasticsearch, Logstash, Kibana): The ELK Stack is like a well-coordinated trio of tools designed to handle your log data.
  • Logstash: Think of Logstash as your personal data curator. It’s responsible for collecting and organizing log information.
  • Elasticsearch: Elasticsearch acts as your dedicated log archive. It meticulously organizes and stores all your log entries.
  • Kibana: Kibana takes on the role of your trusted detective, armed with a magnifying glass. It allows you to visualize and thoroughly inspect your logs. Whether you’re searching for trends, anomalies, or patterns, Kibana has got you covered.
• Splunk: Splunk is the heavyweight champion in the world of log management.
  • This commercial tool comes packed with a wide range of features. It not only excels at log aggregation but also offers powerful searching, monitoring, and analysis capabilities.
  • It provides real-time alerts, dynamic dashboards, and even harnesses the might of machine learning for in-depth log data analysis.