DevOps is emerging fast as a great way to build and deploy applications on-site and cloud alike. Are you hiring or interviewing for a DevOps role? If so, be sure you know the answer to these top DevOps interview questions.
In this article, we will cover some of the most common questions you will see in a typical DevOps interview. Know these answers and base your studies around these questions to put yourself in the best position to get hired!
Use these questions as a springboard for further learning. Use these questions to get a feel for the types of questions you may see in an interview.
DevOps and Business Value
Above all else, DevOps exists because it brings value to an organization. It does this in a few different key ways. Above all, know how DevOps brings business value!
Describe your definition of DevOps
Many people have varying degrees of what DevOps means. But, in a nutshell, DevOps aims to bridge the gap between the development and operations teams. It does this by improving productivity, lowering costs, reducing risk, and shortening cycle times.
DevOps is the collaboration between individuals, processes, and technologies to deliver value to consumers while increasing market agility continuously. It is a collection of cultural philosophies, processes, and tools that quickly improve an organization’s capacity to provide technologies and services.
DevOps can vary based on what organization you’re interviewing at. It can be an organization practicing the true DevOps philosophy or an organization stamping DevOps on a release engineer/platform engineer role. It’s important to understand these distinctions and ask during the interview.
You can ask this question in two ways:
- What does DevOps mean to X company?
- What’s the daily ritual of DevOps in X company?
You can also find this information based on other DevOps employees who work at the company via LinkedIn.
Why would an organization choose to adopt a DevOps model?
An organization may choose to ‘do the DevOps’ based on:
- Improved speed – DevOps enables organizations to build high-quality software through a process of continuous testing, deployment, feedback, and developer bug fixes/changes. This improves the chances of faster time to market.
- Improved collaboration – DevOps facilitates collaboration between team members. If successful, many of the inter-departmental silos are broken down.
- Better security – DevOps promotes integrating security into the development process. Spawning from DevOps, know the term DevSecOps.
- Better feedback – DevOps promotes a full feedback system where customers provide feedback directly to developers.
- Reliability – Through continuous testing, DevOps ensures quality all the way throughout the lifecycle.
Name some situations that would prevent a successful DevOps transformation
If the organization fails at DevOps, be sure to bring about each of these situations, especially with this common DevOps interview question.
- Thinking DevOps is a process. DevOps is not actually a process. It is a philosophy, and it varies from organization to organization.
- Agile and DevOps are the same – Agile is a software development methodology; it does not include people and culture like DevOps does.
- More silos – A department or organizational silo is a mindset that prevents team members from sharing their knowledge with other teams in the organization.
- Responsibility not properly defined – Understanding who is doing what on a team is crucial. Otherwise, the DevOps philosophy will not work.
- Resistance to change – DevOps heavily relies on continuously improving, and doing that requires consistently rethinking what is possible.
- A low-risk tolerance – At least initially, DevOps can introduce more risk to important systems in various ways. If organizations have a conservative management approach, a full-on DevOps rollout will not be successful.
- Thinking that DevOps is build/release – Some organizations typically think DevOps is just a release engineer. You can have an organization practicing the true DevOps philosophy or an organization stamping DevOps on a release engineer/platform engineer role.
Source/Version Control
When a company decides to implement DevOps, finding the right tools for the entire life cycle and providing training to help a team get up to speed with those tools is critical. Be sure you speak to source and version control with these DevOps interview questions.
Out of the suite of tools involved in DevOps, source/version control is most important. Know how to answer these questions!
What is version control?
Developers need a “stake in the ground” when delivering applications to customers. They need a way to label code that is at a specific point. Version control provides them this benefit.
Version control also allows developers to assign versions to a codebase’s state and refer to those versions over time.
What is the source control?
Sometimes used interchangeable, source and version control are similar technologies but serve different purposes. Source control goes farther than simply assigning a number to a state of code.
Source control is a technology that allows developers to communicate and manage all changes made to a codebase efficiently. It does this by tracking all changes to the code and who made that change.
What are some benefits of a source/version control system?
A source/version control system allows you to:
- Compare files, identify differences in the content of files, and merge the changes if needed before committing any code.
- Provide a history of all changes – the change, who changed it, the timestamp, etc.
Explain some branching strategies
Branching is a common DevOps interview question you must come across. It is a strategy used in source/version control to facilitate parallel development. Instead of many developers working on a single codebase together potentially conflicting, they create clones or branches of the main codebase.
Developers then work on their copy of the code and, when complete, merge their code back into the main codebase with everyone else.
A branching strategy is a defined methodology that a team agrees to on how and when to branch and merge code back into the main codebase. Some popular types of branches are:
- Hotfix – Short-term branches meant to fix an issue right away and get merged into the main codebase.
- Feature – A set of changes potentially across more than one developer, all representing a single new feature of a product.
- Develop – A large set of changes across many developers that represent all working changes to a codebase. This branch will eventually be merged with the main codebase as one.
Automated Build and Release Pipelines
One of the most important parts of a DevOps engineer’s job is to manage the automation that delivers the products of code to customers. That automation can be boiled down to build and release pipelines. A pipeline is a workflow that ensures all required actions are taken from the time a developer checks in code to source control when the customer is using that code.
Build and release pipelines have various stages such as development, testing and deployment, and delivery. Each of these stages typically has ‘continuous’ in front of the name because DevOps is about continuously delivering value to customers.
What is a pipeline?
A pipeline is a set of practices used by development and operations teams to plan, track, build, and deliver software. A pipeline is a strictly defined, sequential set of tasks that execute every time a change is detected in code.
A pipeline can have various software development stages to deploy new versions of software to production environments called continuous integration, continuous deployment, and continuous delivery. Each of these pipelines represents how far an organization chooses to automate and define strict processes leading up to the deployment of code into a production environment.
What are the different phases of a DevOps deployment pipeline?
To deliver software to customers, DevOps organizations do this in six general phases.
- Plan – There should be a plan in place that outlines the type of application that is to be built.
- Code – The developers write code as per the requirements of the end-user.
- Build – The code is transformed into packages to deploy to the end customer.
- Test – The code goes through unit testing to ensure no bugs are found.
- Deploy – The application is deployed to an environment – either on-premise or at the cloud where it is tested.
- Monitor – Application performance is monitored, and any changes needed are communicated to the respective developers. Monitoring in a CI/CD pipeline is typically referred to as Continuous Monitoring to ensure what you are expecting throughout the lifecycle is valid.
What is your best description of Continuous Integration, Continuous Deployment, and Continuous Delivery?
Continuous Integration (CI) is a software development practice that requires developers to integrate code changes into a shared, central repository frequently. After the changes are merged, automated tests and builds are run to validate each check-in, allowing teams to detect problems early.
Continuous Delivery integrates all CI provides and also automatically deploys changes to test environments and performs automated testing of those deployment changes. Continuous Delivery is a “manual” effort in the way that it’s not automatically deploying the software to the production environment.
Continuous Deployment automates the final leg of a software journey by automating software deployment directly to production environments.
What is Continuous Testing?
One of DevOps’ core tenants is testing. Developers and build/release engineers must test services continuously. DevOps encourages continuous testing or automated tests that run in just about every part of a pipeline rather than manually testing services.
Continuous testing:
- Enables faster delivery of the software by detecting problems earlier in the software development lifecycle.
- Reduces bugs by making automated testing priority #1
- Provides useful feedback – Feedback is received earlier in the life cycle, which helps build high-quality software.
Explain a few types of testing
Since testing is so paramount in DevOps, DevOps practitioners must segment out various categories of testing. Software and the processes that deliver that software must be tested constantly.
Know these types of testing for any DevOps interview question.
- Unit testing – Unit testing is a testing methodology that tests units of code to check if they conform to the stated requirements. Unit tests are executed during the build process. During unit testing, functionality is commonly mocked or replaced the dummy information to segment out various functionality.
- Integration/Smoke/Verification Testing
Once the code itself has been testing, the code must be integrated into an environment. It must be deployed to a system and ran. Testing this functionality has many different names but most commonly is referred to as integration testing.
Integration tests are performed at the integration of the compiled code and a testing environment.
- Acceptance Testing
During a deployment pipeline, the last phase of testing is known as acceptance testing. Acceptance does not test the code nor the fact that it was integrated correctly into an environment. Acceptance testing tests the final outcome of the software.
For example, an acceptance might test whether or not a web server returns an HTTP/200 message or a web page displays a correct page.
Configuration Management
Code must have somewhere to run on, and that somewhere needs to be configured to a proper specification and stay there. This is where configuration management comes in.
What is configuration management and why is it important?
Software must be deployed to an environment. It must run on a server of some kind. That server then has various configuration items to configure it as an organization expects, such as patching, files, services running, etc. Configuration management handles all of that.
Configuration Management is a system engineering process that builds and maintains configuration items and establishes and maintains a product’s consistency over its life cycle.
Configuration Management process provides the following benefits and may just be your next DevOps interview question.
- Reduces risk – through proper detection and correction of improper configurations, risk factors are reduced and your business can benefit from improved business agility and faster problem resolution
- Improves reliability – Supports better change management and faster restoration of your services in the event of a process failure
- Reduces cost – Knowledge of all elements of the configuration helps eliminate unnecessary duplication of effort.
What is Infrastructure as Code and why is it important?
Infrastructure-as-Code (IaC) is a way to define infrastructure and services as code. You can think of IaC as configuration as code. It defines the instructions infrastructure-provisioning tools can then carry out to build the infrastructure organizations need.
IaC helps in a few different ways:
- Quicker infrastructure provisioning – Using automated tools, organizations can build infrastructure much quicker than doing it manually.
- Consistency – Using automated tooling like IaC tools ensures infrastructure is provisioned the same way every time.
- Reduced management overhead – IaC promotes shorter feedback loops and effective change management since it’s defined in code.
Containerization and Virtualization
When it comes to infrastructure in a DevOps world, you won’t get away from some virtualization technology. We once had virtual machines that virtualized servers, but now we have faster, more lightweight, and more efficient containers.
What are containers?
No DevOps interview question is complete without one on containers. A container is a lightweight, virtualized operating system that rides on top of a host sharing the host’s kernel. A container encapsulates a service’s dependencies in a single package to ensure that software can run on many different environments.
Containerization bundles the code and all its necessary dependencies that are needed for the application to run. Containers enable “portable” applications to be written once and run anywhere.
What is the difference between containers and virtual machines?
A container is an isolated, lightweight silo that runs a program on the host operating system and provides a lightweight means of addressing virtualization. Containerization runs on a layer right above the hardware itself, unlike a virtual machine (VM).
A VM is a software application that emulates the features of actual hardware or a computational device and runs on top of the host’s operating system. Although virtual machines provide isolation from the host operating system, containers provide lightweight isolation from the host and other containers.
What are the advantages of containerization over virtualization?
While virtualization enables the running of multiple operating systems on a single physical server, containerization enables the running of multiple applications on a single virtual machine, running the same operating system.
The main advantages of containerization are:
- Flexibility – Light-weight and can be started and stopped in seconds
- Security – Support for isolation provides better security
- Portability – Enables you to deploy anywhere – even in hybrid environments
- Agility – You don’t actually need an OS to run. Containers are a good choice for tasks that have a much shorter lifecycle.
- Fault isolation – Each containerized application is separate from one another and runs independently. The failure of one container doesn’t have any impact on the function of the other containers.
What is Docker and why is it important?
Docker is a popular software platform for developing containerized applications. It is the de-facto standard for developing and sharing containerized applications.
Docker is basically a container engine that builds containers on top of an operating system using Linux Kernel features like namespaces and control groups.
Even though container technology has been around for many years before Docker, Docker changed the game because it made containers more accessible. It enabled everyone to take advantage of containers and allow users to manage containers more easily.
What is Kubernetes and why it is important?
Kubernetes is an open-source container orchestration tool used to simplify activities such as containerized configuration management, testing, scaling, and deployment. It is used to efficiently handle several containers, allowing for the discovery and management of logical units.
Kubernetes is a cluster technology that consists of servers and services running on those servers known as nodes. Each node has a specific purpose, such as a master node to act as the orchestrator to worker nodes that actually run the containers.
How do Docker and Kubernetes compare against each other?
Docker is a container lifecycle management system that uses a Docker image to create runtime containers. Kubernetes, on the other hand, is a solution for managing those containers.
Docker Swarm is a competing product with Kubernetes. Docker Swarm is used for clustering and scheduling Docker containers. Kubernetes supports auto-scaling while Docker Swarm doesn’t. Unlike Docker Swarm, Kubernetes has built-in resources for logging and tracking.
