Preparing for a DevOps Interview: Key Technical Questions and How to Answer Them
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by Sam Healy
Job Interview Preparation
As a recruiter, I often see candidates grappling with technical questions during interviews. It's essential to not only understand the questions but also to prepare answers that reflect your expertise, the role's seniority, and the specific tech stack. Employers are not there to catch you out or make things difficult for you. At the end of the day, they are hoping you are the right person for the job.
Some processes are tougher than others, they are usually designed as means to make sure that the person they are hiring is bang on what they need and want. So, preparing as best you can and being what that employer needs you to be is vital. I don’t mean be something else in order to get the job, be yourself but make the subtle adjustments needed to give yourself the best chance possible. Here's a curated list of common technical questions you might encounter, along with tips on preparation and typical answers to help you stand out and be the best version of yourself during your interviews.
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What is Infrastructure as Code (IaC)? Explain its importance in DevOps.
How to Prepare:
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Understand the Concept: Know what IaC is and why it’s crucial in a DevOps environment.
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Familiarise with Tools: Learn about common IaC tools like Terraform, Ansible, and CloudFormation.
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Real-World Examples: Be ready to discuss scenarios where IaC was beneficial in your experience.
Typical Answer:
"Infrastructure as Code (IaC) is the practice of managing and provisioning computing infrastructure through machine-readable configuration files, rather than through physical hardware configuration or interactive configuration tools. It is important in DevOps because it allows for consistent and repeatable deployments, reduces the risk of human error, and improves efficiency. For example, using Terraform, I have automated the deployment of cloud resources, ensuring that our staging and production environments are identical, which has significantly reduced deployment issues."
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How do you handle configuration management? Which tools have you used?
How to Prepare:
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Tool Proficiency: Gain hands-on experience with tools like Puppet, Chef, Ansible, or SaltStack.
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Configuration Management Strategies: Understand best practices and how these tools support them.
Typical Answer:
"Configuration management is essential for maintaining consistency across servers and ensuring that all environments are configured correctly. I have used Ansible extensively for this purpose. Ansible's playbooks allow for idempotent operations, meaning that I can run the same script multiple times without affecting the final state of the system. This has been particularly useful in ensuring that all servers are configured uniformly."
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Can you describe your experience with CI/CD pipelines?
How to Prepare:
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Pipeline Components: Understand the components of a CI/CD pipeline (source control, build, test, deploy).
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Tools and Practices: Familiarise yourself with tools like Jenkins, GitLab CI, Travis CI, and CircleCI.
Typical Answer:
"I have designed and maintained CI/CD pipelines using Jenkins. The pipeline automates the entire process from code commit to deployment. It integrates with Git for version control, runs unit and integration tests, and deploys the application to our staging environment. This setup has significantly reduced our time to market by enabling continuous feedback and rapid iteration."
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Image by vectorjuice on Freepik
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What strategies do you use for monitoring and logging in a production environment?
How to Prepare:
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Monitoring Tools: Learn about monitoring tools like Prometheus, Grafana, Nagios, and Datadog.
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Logging Practices: Understand logging best practices and tools like ELK Stack (Elasticsearch, Logstash, Kibana), Splunk, and Fluentd.
Typical Answer:
"Monitoring and logging are crucial for maintaining the health of production systems. I use Prometheus for monitoring because of its powerful query language and Grafana for visualisation. For logging, we utilise the ELK stack, which allows us to centralise and analyse logs from different services. This setup helps in quickly identifying and resolving issues, ensuring minimal downtime."
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Explain how you manage containerization and orchestration. Which tools do you use?
How to Prepare:-
Container Basics: Understand the basics of containerization with Docker.
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Orchestration Knowledge: Learn about orchestration tools like Kubernetes and Docker Swarm.
Typical Answer:
"Containerization allows for consistent environments across development, testing, and production. I use Docker for containerization and Kubernetes for orchestration. Kubernetes manages containerized applications across a cluster of machines, automating deployment, scaling, and operations. This has enabled us to deploy applications more efficiently and ensure high availability."
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What is your approach to managing secrets and sensitive information?
How to Prepare:
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Secret Management Tools: Familiarise yourself with tools like HashiCorp Vault, AWS Secrets Manager, and Kubernetes Secrets.
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Security Practices: Understand best practices for managing secrets securely.
Typical Answer:
"Managing secrets is critical for maintaining security. I use HashiCorp Vault to store and access secrets securely. Vault provides encryption as a service, allowing us to manage access and ensure that sensitive information is encrypted at rest and in transit. We also follow best practices such as rotating secrets regularly and using environment-specific secrets."
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How do you ensure high availability and disaster recovery in your infrastructure?
How to Prepare:
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High Availability Strategies: Understand concepts like load balancing, failover, and redundancy.
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Disaster Recovery Planning: Learn about backup strategies and recovery procedures.
Typical Answer:
"To ensure high availability, I implement load balancing using tools like HAProxy or AWS Elastic Load Balancing to distribute traffic across multiple instances. For disaster recovery, we maintain regular backups and use automated scripts to restore services quickly. We also conduct regular disaster recovery drills to ensure that our team is prepared for any scenario."
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Can you discuss a challenging incident you encountered and how you resolved it?
How to Prepare:
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Incident Details: Reflect on past incidents, focusing on the problem, your actions, and the outcome.
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Resolution Skills: Highlight your problem-solving skills and ability to work under pressure.
Typical Answer:
"One challenging incident involved a sudden spike in traffic that caused our application to crash. I quickly identified that the root cause was a misconfigured auto-scaling policy. I adjusted the scaling policy to handle higher loads and added more instances to the cluster. Additionally, I implemented better monitoring and alerting to prevent similar issues in the future. This experience reinforced the importance of proactive monitoring and having robust scaling policies."
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Preparing for a DevOps interview involves understanding both the theoretical concepts and practical applications of various tools and practices. Remember, the level of detail in your answers should match your experience and the role's seniority. Junior candidates should focus more on their learning and experiences, while senior candidates should demonstrate a deeper understanding and strategic thinking. Tailoring your answers to the specific tech stack and requirements of the job you're applying for will also make a significant difference.
Always study the job spec in the weeks leading into your interview, which was designed specifically for the role. And, as an even better solution to helping you prepare, work with a recruiter from an agency such as GemPool. My job is to help you as best I can through the whole process. We work specifically with hiring managers to understand what they need, so who wouldn’t want that person in their corner? If you’re looking for a new job at this moment, we’re hiring. Head over to our careers page now to explore.
Cover image credits: Image by macrovector on Freepik
