DevOps Interview Prep Guide

This guide is designed to help mid-level DevOps candidates prepare for roles in London's thriving tech ecosystem.
It covers essential skills, tools, and topics commonly tested in interviews, tailored to the needs of startups, FinTechs, and enterprises.

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📋 Core Topics to Master

1. Cloud Platforms

Familiarise yourself with the top cloud platforms used in the UK:

• AWS: EC2, S3, RDS, Lambda, CloudFormation.
• Azure: Azure DevOps, AKS, Virtual Machines, Functions, App Services.
• Google Cloud Platform (GCP): GKE, BigQuery, Pub/Sub.
• Multi-Cloud Tools: Terraform, Pulumi.

Example Questions:

• "What are the trade-offs between using managed services versus self-hosted solutions?"
• "How do you implement a multi-cloud strategy for high availability?"

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2. Infrastructure as Code (IaC)

Learn how to automate infrastructure setup with:

• Tools: Terraform, Ansible, CloudFormation, Pulumi.
• Focus Areas: Modular templates, state management, and automation.

Example Questions:

• "How do you manage state files in Terraform for a multi-team environment?"
• "Explain the differences between Terraform and Ansible in a DevOps workflow."

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3. CI/CD Pipelines

Master continuous integration and delivery pipelines:

• Tools: Jenkins, GitLab CI/CD, CircleCI, Azure DevOps, ArgoCD.
• Key Concepts: Automated testing, rollback strategies, blue-green deployments.

Example Questions:

• "Describe how you set up a CI/CD pipeline for a microservices architecture."
• "How would you automate rollbacks for a failed deployment?"

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4. Containers and Orchestration

Understand how to manage containerised applications:

• Tools: Docker, Kubernetes (AKS, EKS, GKE), Helm, OpenShift.
• Key Skills: Deploy, scale, and troubleshoot applications.

Example Questions:

• "How do you troubleshoot a failing Kubernetes pod?"
• "What are the pros and cons of using Helm for managing Kubernetes applications?"

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5. Monitoring and Logging

Set up observability systems for distributed applications:

• Tools: Prometheus, Grafana, ELK Stack, Datadog, Splunk, New Relic.
• Focus: Dashboards, alerts, log aggregation, and distributed tracing.

Example Questions:

• "How would you design a monitoring solution for a highly distributed system?"
• "What are the key metrics you track for a Kubernetes-based application?"

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6. Networking and Security

DevOps professionals need solid networking and security knowledge:

• Networking: DNS, load balancers (NGINX, HAProxy), VPCs, subnets, VPNs.
• Security: IAM, TLS/SSL, firewalls, secrets management (e.g., HashiCorp Vault).
• Compliance: GDPR and secure pipelines.

Example Questions:

• "How do you securely manage API keys and other sensitive information in a CI/CD pipeline?"
• "Describe how you implement a Zero Trust Security model."

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7. Scripting and Automation

Proficiency in scripting is a must:

• Languages: Bash, Python, PowerShell.
• Focus Areas: Automating repetitive tasks, infrastructure provisioning.

Example Questions:

• "Write a script to automate the provisioning of EC2 instances with a specific configuration."
• "What are the benefits of using Python over Bash for automation?"

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🤔 Behavioral and Scenario-Based Questions

• "Describe a time when you resolved a critical production issue. What was your approach?"
• "Tell me about a time you improved the efficiency of a DevOps pipeline."
• "You are tasked with migrating a legacy system to Kubernetes. Walk us through your plan."
• "How do you handle conflicts when working with developers or operations teams?"

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🎓 Recommended Certifications

Certifications that stand out in the UK market:

• AWS Certified DevOps Engineer – Professional
• Microsoft Certified: Azure DevOps Engineer Expert
• Certified Kubernetes Administrator (CKA)
• HashiCorp Terraform Associate

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📚 Study Resources

Books

• "The Phoenix Project" by Gene Kim.
• "Kubernetes Up and Running" by Kelsey Hightower.
• "Terraform: Up & Running" by Yevgeniy Brikman.

Courses

• A Cloud Guru – AWS, Azure, Kubernetes.
• KodeKloud – Hands-on Kubernetes and DevOps.
• Udemy – DevOps and IaC.

Hands-On Practice

• Instruqt: DevOps challenges.
• Katacoda: Kubernetes labs.
• GitHub: Create projects showcasing pipelines, Terraform modules, or Kubernetes deployments.

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🔥 Tips for the London Market

1. Understand Compliance Needs: Be familiar with GDPR and how it impacts DevOps workflows.
2. Showcase Cost Optimization Skills: Many UK companies prioritize cost-efficient solutions, especially startups.
3. Prepare for Cultural Fit Questions: Highlight teamwork and collaboration in diverse, international teams.
4. Adapt to Startup vs. Enterprise: Startups expect end-to-end ownership, while enterprises look for specialisation in tools like Azure DevOps or Kubernetes.

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🙌 Contribute

Have suggestions or improvements? Feel free to submit a pull request or open an issue!

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This guide is a living document. It will be updated regularly to reflect the latest industry trends and tools. Good luck with your interview preparation! 🚀