Google Kubernetes Engine Interview Questions and Answers for 7 years experience

1. What is Kubernetes?

   • Answer: Kubernetes is an open-source container orchestration system for automating deployment, scaling, and management of containerized applications. It groups containers that make up an application into logical units for easy management and discovery.

2. Explain the core concepts of Kubernetes: Pods, Deployments, Services, Namespaces.

   • Answer: Pods are the smallest deployable units in Kubernetes, containing one or more containers. Deployments manage the desired state of a set of Pods, handling updates and rollouts. Services provide a stable IP address and DNS name for a set of Pods, enabling communication. Namespaces provide logical separation of resources within a cluster.

3. Describe different Kubernetes deployment strategies.

   • Answer: Common strategies include rolling updates (gradual replacement of old pods with new ones), blue/green deployments (running two versions simultaneously), canary deployments (releasing a new version to a small subset of users), and Recreate (terminating all old pods before deploying new ones).

4. How does Kubernetes handle scaling?

   • Answer: Kubernetes automatically scales applications based on resource utilization (CPU, memory) or custom metrics using Horizontal Pod Autoscaler (HPA). Manual scaling is also possible by adjusting the replica count in deployments.

5. Explain Kubernetes networking. How do pods communicate with each other?

   • Answer: Kubernetes uses a network plugin to provide networking for pods. Pods communicate through their IP addresses, which are assigned by the network plugin. Services provide a stable endpoint for accessing pods, abstracting away the underlying pod IP addresses.

6. What are Kubernetes Persistent Volumes (PVs) and Persistent Volume Claims (PVCs)?

   • Answer: PVs represent storage resources provisioned by the cluster administrator, while PVCs are requests by pods for storage. They provide persistent storage for stateful applications.

7. What are ConfigMaps and Secrets in Kubernetes?

   • Answer: ConfigMaps store configuration data, and Secrets store sensitive information like passwords and API keys. Both are used to externalize application configuration, making deployments more secure and manageable.

8. How do you troubleshoot a Kubernetes pod that's not running?

   • Answer: Check pod logs using `kubectl logs `, examine the pod's events using `kubectl describe pod `, verify resource limits and requests, check the node status, and analyze network connectivity.

9. Explain the role of a Kubernetes controller.

   • Answer: Controllers are responsible for maintaining the desired state of the cluster. They constantly monitor the state of the cluster and take actions to reconcile any discrepancies between the desired and actual state. Examples include Deployment Controller, ReplicaSet Controller, and StatefulSet Controller.

10. What are different ways to access your applications running in GKE?

    • Answer: Through a LoadBalancer service (exposes application externally), Ingress controller (provides routing and load balancing), NodePort (exposes service on each node's IP), or directly via kubectl port-forward.

11. Describe how to manage Kubernetes secrets securely.

    • Answer: Use Kubernetes Secrets, avoid hardcoding secrets in application code, leverage secret management tools like HashiCorp Vault or Google Cloud Secret Manager, and use least privilege access controls.

12. Explain the concept of Kubernetes RBAC (Role-Based Access Control).

    • Answer: RBAC allows you to control access to Kubernetes resources based on roles and permissions, enhancing security and limiting the impact of compromised credentials.

13. What is a StatefulSet in Kubernetes? When would you use it?

    • Answer: A StatefulSet manages stateful applications that require persistent storage and stable network identities. Use it for databases, message queues, or other applications requiring persistent data and consistent network names.

14. What is a DaemonSet in Kubernetes? Give an example use case.

    • Answer: A DaemonSet ensures that every node in a cluster runs a copy of a pod. Use cases include running system daemons, logging agents, or network plugins.

15. Explain the difference between a Deployment and a ReplicaSet.

    • Answer: A Deployment manages a ReplicaSet, providing declarative updates and rollouts. ReplicaSets manage the desired number of pod replicas based on a selector.

16. What are some best practices for designing Kubernetes applications?

    • Answer: Design for microservices architecture, use immutable infrastructure, implement proper logging and monitoring, use appropriate resource limits and requests, design for fault tolerance and high availability, and leverage Kubernetes features like RBAC and namespaces.

17. How do you monitor the health of your GKE cluster?

    • Answer: Use Google Cloud Monitoring, Prometheus, Grafana, or other monitoring tools to track node health, pod status, resource utilization, and application performance.

18. Describe different methods for backing up and restoring Kubernetes data.

    • Answer: Methods include using etcd backups (for cluster state), backing up persistent volumes (for application data), and leveraging cloud-native backup solutions.

19. How do you secure a GKE cluster?

    • Answer: Implement RBAC, enable strong authentication mechanisms (like Google Cloud IAM), use network policies to restrict pod communication, regularly patch nodes and components, and audit cluster activity.

20. Explain the different GKE node pools and their purpose.

    • Answer: GKE allows creating multiple node pools with different machine types, allowing for optimization of resource allocation for different workloads. This helps manage costs and performance effectively.

21. What are Autopilot and its benefits in GKE?

    • Answer: GKE Autopilot is a fully managed node management service. It simplifies cluster management and operations while optimizing performance and resource utilization. It handles node provisioning, scaling, and updates automatically.

22. How do you manage and update Kubernetes configurations (e.g., using YAML files)?

    • Answer: Use `kubectl apply -f ` to apply configurations and `kubectl edit ` to edit them directly. Version control is crucial for managing configurations.

23. Explain the concept of Kubernetes resource quotas and limits.

    • Answer: Resource quotas control the amount of resources (CPU, memory, etc.) a namespace can consume. Resource limits enforce constraints on individual pods, preventing resource starvation.

24. How would you troubleshoot a network connectivity issue between Kubernetes pods?

    • Answer: Examine pod logs for networking errors, verify network policies, check the service definitions, and use `kubectl describe pod` and `kubectl describe service` to gather more information. Tools like `tcpdump` or Wireshark might be necessary.

25. What are some common Kubernetes performance bottlenecks and how can you address them?

    • Answer: Bottlenecks include insufficient CPU/memory, network congestion, slow storage, and inefficient application code. Solutions involve adjusting resource requests/limits, optimizing application code, upgrading hardware, and investigating network issues.

26. How does Kubernetes handle pod failures and ensure high availability?

    • Answer: Kubernetes monitors pod health and restarts failed pods automatically. ReplicaSets ensure that the desired number of pods are running, and features like liveness and readiness probes help determine pod health.

27. What are the benefits of using Helm in Kubernetes?

    • Answer: Helm simplifies packaging, deploying, and managing Kubernetes applications. It uses charts to define application dependencies and configurations, making deployments easier to manage and reproduce.

28. Describe your experience with different cloud providers' Kubernetes offerings (besides GKE).

    • Answer: [Candidate should describe their experience with AWS EKS, Azure AKS, or other Kubernetes services. Details should be tailored to their specific experience.]

29. How would you migrate an existing application to GKE? What are the key steps?

    • Answer: Key steps include containerizing the application, creating Kubernetes manifests (YAML files), deploying the application to GKE, testing the deployment, and monitoring application performance. Consider a phased migration approach for large applications.

30. What are some common challenges you've faced working with GKE, and how did you overcome them?

    • Answer: [Candidate should describe specific challenges they faced and the steps taken to resolve them. This should demonstrate problem-solving skills and practical experience.]

31. Explain your experience with using Kubernetes APIs.

    • Answer: [Candidate should detail their experience using the Kubernetes API, either directly or through tools like kubectl, to manage and interact with the cluster. Examples of tasks performed should be given.]

32. What are your preferred tools and techniques for monitoring and logging in a GKE environment?

    • Answer: [Candidate should specify their preferred tools, such as Google Cloud Logging, Prometheus, Grafana, Fluentd, etc. Their answer should include a rationale for their choices and describe how these tools integrate with their workflows.]

33. How do you ensure the security and compliance of your GKE deployments?

    • Answer: [Candidate should describe their approach to security and compliance, including practices like RBAC, network policies, secrets management, auditing, and adherence to industry standards and regulations.]

34. Describe your experience with automating Kubernetes deployments using CI/CD pipelines.

    • Answer: [Candidate should describe their experience with CI/CD tools like Jenkins, GitLab CI, CircleCI, or others, and how they have used them to automate building, testing, and deploying applications to GKE.]

35. What are your experiences with different GKE pricing models and how do you optimize costs?

    • Answer: [Candidate should discuss their understanding of GKE pricing, including node pools, preemptible instances, and other cost-saving features. They should also describe their strategies for optimizing costs in their deployments.]

36. How do you handle application rollbacks in GKE?

    • Answer: [Candidate should explain how to use Kubernetes features like deployments' rollback capabilities to revert to previous versions of applications in case of failures or issues.]

37. Explain your understanding of Kubernetes resource limits and requests. How do you determine appropriate values?

    • Answer: [Candidate should articulate their understanding of resource limits and requests and describe their process for determining suitable values based on application requirements and historical usage data.]

38. How do you troubleshoot issues related to GKE networking, including ingress and service configurations?

    • Answer: [Candidate should outline their troubleshooting methodology, including using kubectl commands, checking logs, and reviewing network configuration files, to identify and fix networking problems.]

39. Describe your experience with different storage solutions within GKE, such as Persistent Volumes and Cloud Storage.

    • Answer: [Candidate should discuss their experience with different storage options and their suitability for various application needs. They should also mention their expertise in managing persistent volumes and claims.]

40. How do you manage and scale your GKE clusters effectively?

    • Answer: [Candidate should discuss their approach to cluster scaling, including horizontal pod autoscaling, manual scaling, node pool management, and cluster autoscaling, and highlight their strategies for maintaining optimal performance and cost efficiency.]

41. What are your experiences with using Istio or other service meshes within GKE?

    • Answer: [Candidate should share their knowledge of service meshes, including their purpose and benefits, and their experience using Istio or other similar tools within GKE. If no experience, they should honestly state that and describe their understanding of the concept.]

42. How do you ensure high availability and disaster recovery for your GKE deployments?

    • Answer: [Candidate should describe their strategies for ensuring high availability and disaster recovery, including multi-region deployments, using managed services, and implementing backup and restore procedures.]

43. Discuss your experience with troubleshooting and resolving issues related to GKE node failures.

    • Answer: [Candidate should describe their troubleshooting process for node failures, including using monitoring tools, checking logs, and taking appropriate actions such as replacing failed nodes or investigating root causes.]

44. What is your understanding of Kubernetes custom resource definitions (CRDs)?

    • Answer: [Candidate should describe their knowledge of CRDs and their use in extending the Kubernetes API to manage custom resources and operators.]

45. Describe your experience with Kubernetes operators.

    • Answer: [Candidate should describe their understanding and experience with Kubernetes operators, including their purpose, implementation, and use in managing complex stateful applications.]

46. How do you approach performance tuning and optimization in GKE environments?

    • Answer: [Candidate should describe their strategies for performance tuning, including using profiling tools, optimizing application code, adjusting resource requests and limits, and using efficient storage solutions.]

47. What are some of the security best practices you follow when working with GKE?

    • Answer: [Candidate should outline their security practices, including network policies, RBAC, secrets management, image scanning, and vulnerability management.]

48. Describe your experience with managing and upgrading GKE clusters.

    • Answer: [Candidate should describe their process for managing and upgrading GKE clusters, including planning, testing, and executing upgrades, as well as handling potential issues during upgrades.]

49. What are your experiences with different logging and monitoring tools in GKE, and how do you correlate logs and metrics for troubleshooting?

    • Answer: [Candidate should describe their experience with various logging and monitoring tools, and their techniques for correlating logs and metrics to effectively troubleshoot issues.]

50. How do you handle unexpected downtime or outages in your GKE deployments?

    • Answer: [Candidate should describe their approach to handling downtime, including their process for identifying the root cause, implementing temporary workarounds, and preventing future occurrences.]

51. Describe a complex technical challenge you faced while working with GKE and how you solved it.

    • Answer: [Candidate should describe a specific challenge, outlining the problem, their approach to solving it, the solution they implemented, and the outcome.]

52. How do you stay up-to-date with the latest advancements and best practices in Kubernetes and GKE?

    • Answer: [Candidate should describe their methods for staying current, including following blogs, attending conferences, participating in online communities, and reading official documentation.]

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