Microservices Interview Questions for AWS Candidates

by | May 11, 2022 | Hiring

Microservices interview questions should be an essential part of your hiring process for AWS engineers. In this post, we’ll cover the importance and benefits of microservices and provide you with some interview question ideas.

When you’re ready to put what you’ve learned into practice, hop on over to our AWS talent solutions page. re solution, Nerdly, makes it easy to find and interview cloud professionals for hourly, project, contract, and contract-to-hire positions. If you’re looking to hire full-time, our team of cloud recruitment consultants is ready to help fill your candidate pipeline with top talent.

The importance of microservices

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Before we jump into some microservices interview questions, it’s important to understand why you’re asking them. If you work in a technical role or come from a technical background, feel free to skip ahead. But if you don’t have technical experience, take a moment to orient yourself.

Microservices are small, loosely-coupled software services connected via well-defined APIs that can be independently deployed and easily reused. They’re an integral part of building your cloud infrastructure according to the AWS Well-Architected Framework. As opposed to tightly-coupled, monolithic infrastructures that can crumble when one service breaks, infrastructures built with microservices use loose coupling for more resilient cloud environments.

An illustration of a monolithic vs microservices architecture.

In a monolithic architecture, software services are bound by custom integrations. This can result in rigid and brittle infrastructures that have to scale up to meet demand.

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But with a microservice design, software services are loosely-coupled via well-defined APIs, with a focus on creating reusable and interchangeable components. Using microservices leads to a more complex environment, but taking this approach offers numerous advantages over traditional architectures.

The benefits of using microservices

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In addition to making for more resilient cloud infrastructures, microservices offer a number of benefits, including:

  • Scalability. Because microservices can run independently and distribute tasks across multiple machines, using them makes for faster, easier horizontal scaling. This can also save you money, since scaling out is less expensive than scaling up.
  • High availability. Increased scalability translates to high availability. You can deploy microservices independently, freeing you up to make changes to other software components or the server itself without taking down an application. This paired with fault isolation makes for reduced downtime for end users.
  • Easier deployment. Unlike monolithic architectures, microservice architectures pose less risk for dependency conflicts. This lets you take advantage of containers and gives you access to multiple deployment options instead of just one.
  • Easier code maintenance and testing. Compared to monolithic architectures, microservices don’t require large, siloed teams of developers. Smaller, self-contained development teams can test software changes and conduct maintenance more easily.

Of course, microservices come with a variety of other benefits that I either didn’t mention above or that might be specific to your organization. Regardless, most good AWS engineer candidates should be able to speak to these four benefits in an interview.

Microservices interview questions

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Now that you have some more context around microservices, let’s look at some questions you might ask a candidate in an interview.

1. What are microservices?

Microservices are an approach to software development where small, loosely-coupled services communicate with each other. Microservices can be deployed independently and usually focus on creating reusable and interchangeable software components. Unlike monolithic architectures, microservices are connected by well-defined APIs instead of custom integrations.

2. What are the benefits of microservices?

Refer to the previous section. Microservices offer numerous benefits, including but not limited to: scalability, agility, resiliency, ease of deployment, operational efficiency, and availability.

3. Explain containers to me. How do they relate to microservices?

Containers are lightweight packages for your microservices-based applications, whereas microservices are a way to build applications. Microservices are what you’d use to make an application. Containers are what you’d use to deploy the application.

4. What’s the advantage of using AWS Lambda instead of EC2 to develop microservices?

Lambda is serverless, meaning you don’t have to worry about managing servers—just writing code. While Auto Scaling is available for Amazon EC2, Lambda scales automatically by default.

5. What is Amazon ECS? Which is better to use for maximum integration with other AWS services—ECS or Kubernetes?

ECS stands for Elastic Container Service. It’s a container orchestration service with Docker support that lets you run your containerized applications on AWS. You can also run containerized applications on AWS using Kubernetes, but ECS offers deeper integration with other AWS services. If you still want to use Kubernetes for container orchestration but don’t want to deal with your own cluster management infrastructure, you could also use Elastic Kubernetes Service (AWS EKS).

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6. What’s the difference between microservices and SOA?

Microservice architecture is closely related to service-oriented architecture (SOA). In fact, microservices evolved out of SOA. But while SOA is focused on software development for the organization as a whole across multiple applications, microservices are focused on software development for an application. Both emphasize loose coupling and reusable software components.

7. In a microservice architecture, what is the function of API Gateways?

API Gateways manage requests from the client, usually from a mobile or web application.

8. What’s the advantage of using API Gateways over direct client-to-microservice communication?

You might hear a variety of responses for this, but one important consideration is that a direct client-to-microservice architecture usually results in a lot of back end requests, increasing latency and ultimately slowing down your application. If it’s a smaller microservice-based app, you might get by okay with a direct client-to-microservice infrastructure, but otherwise it’s best to use API Gateways.

9. Explain bounded context to me.

According to Microsoft, a bounded context is “…the boundary within a domain where a particular domain model applies.” Bounded context is a central concept of domain-driven design (DDD).

10. What is Spring? Why is it important to microservices?

Spring is an open source Java framework developed by VMware. It offers at least two modules that are useful for building microservice-based applications: Spring Boot and Spring Cloud. Spring Boot provides a platform for developers to quickly build standalone Spring applications. Spring Cloud is an integration tool that lets you integrate your microservices with external systems.

11. What design pattern would you use for microservices that don’t need to communicate with each other in a certain order?

The design pattern that makes the most sense here is an asynchronous messaging design pattern. Unlike a chain or chain of responsibility design pattern, asynchronous messaging lets a client make requests to multiple services simultaneously to produce a faster output. Services in this design pattern can still communicate with each other—they just don’t have to do so sequentially.

What not to ask candidates

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You want to ensure the candidate you’re interviewing has a firm understanding of microservices, but that doesn’t necessarily mean it’s a good idea to try stumping them with basic or highly technical questions.

Posing very basic microservices questions to a good candidate is a waste of time for both parties. Interviewers sometimes include these questions in an attempt to weed out rookies, but the truth is, most of those candidates likely won’t have made it past an initial phone interview, anyway.

Best case scenario, you don’t learn anything meaningful about the candidate. Worst case scenario, you frustrate the candidate and possibly turn them off from wanting to work at your company.

Highly technical questions can also prove unhelpful. No developer knows everything there is to know about microservices, and that’s okay. In fact, they don’t need to. Rather than really putting a developer’s knowledge to the test, highly technical questions tend to be impractical and tedious.

Often these questions are so obscure that they only apply in specific (usually one-off) situations. The internet is full of reference resources for microservices, and it’s perfectly fine for developers to make use of them—especially if the information in question isn’t useful to remember most of the time.

Find the right fit with NerdRabbit

Knowing which interview questions you’ll ask a candidate is a small piece of the hiring puzzle. At NerdRabbit, we’re pros at helping you find the right talent for your open positions. Post an opportunity to our online platform, Nerdly, to interview, hire, and pay hourly, project, and contract workers. Or let our cloud recruitment consultants fill your full-time candidate pipeline for you.

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Hourly, contract, contract-to-hire, full-time—we've got you covered. Explore our cloud talent solutions today to get the help you need.

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About Forrest Brown
Forrest Brown is the Content Manager at NerdRabbit. An AWS Certified Cloud Practitioner, he lives in Atlanta with his wife and two cats.

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