Google Kubernetes Engine Interview Questions and Answers for 10 years experience

1. What is Kubernetes?

   • Answer: Kubernetes is an open-source container orchestration platform designed to automate deployment, scaling, and management of containerized applications across a cluster of hosts. It groups containers that make up an application into logical units for easy management and scaling.

2. Explain the architecture of a Kubernetes cluster.

   • Answer: A Kubernetes cluster consists of a control plane (master nodes) and worker nodes. The control plane manages the cluster state and worker nodes run the pods. Key components include the kube-apiserver, etcd (for persistent storage), kube-controller-manager, kube-scheduler, and worker nodes with kubelet and kube-proxy.

3. What are Pods, Deployments, and StatefulSets? Explain the differences.

   • Answer: Pods are the smallest deployable units in Kubernetes, representing a running instance of an application. Deployments manage pods, ensuring a desired number of pods are running and handling updates. StatefulSets are used for applications requiring persistent storage and unique identities, crucial for databases or stateful services.

4. What are Services in Kubernetes? Explain different types.

   • Answer: Services provide a stable IP address and DNS name for a set of Pods. Types include ClusterIP (internal), NodePort (external via node IPs), LoadBalancer (cloud provider managed), and Ingress (for external access with advanced routing).

5. Explain Kubernetes Namespaces.

   • Answer: Namespaces provide a way to logically separate resources within a single cluster. This allows for better organization, resource isolation, and access control. Different teams or projects can use namespaces to avoid conflicts.

6. What are ConfigMaps and Secrets?

   • Answer: ConfigMaps store non-sensitive configuration data, while Secrets store sensitive information like passwords and API keys. Both allow configuration data to be managed separately from application code, improving security and maintainability.

7. How does Kubernetes handle scaling?

   • Answer: Kubernetes uses Horizontal Pod Autoscaler (HPA) to automatically scale the number of Pods based on metrics like CPU utilization or custom metrics. Manual scaling is also possible through deployments.

8. Describe the Kubernetes rolling update process.

   • Answer: Rolling updates gradually replace older Pods with newer versions without causing downtime. Kubernetes creates new Pods with the updated image, waits for them to become healthy, and then terminates the old Pods.

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

   • Answer: PVs represent storage that Kubernetes can manage. PVCs are requests for storage by Pods, which are then bound to PVs. This allows Pods to access persistent storage across their lifecycle.

10. Explain Kubernetes Ingress.

    • Answer: Ingress is an API object that manages external access to services in a cluster. It typically uses a reverse proxy like Nginx or HAProxy to route traffic based on hostname or path.

11. What is a Kubernetes Job?

    • Answer: A Job runs a finite number of Pods and ensures a specific number of them successfully complete. Used for batch processing or one-off tasks.

12. What is a CronJob?

    • Answer: A CronJob schedules Jobs to run periodically based on a cron expression, similar to Unix crontab.

13. What are DaemonSets?

    • Answer: DaemonSets ensure a single instance of a Pod is running on each node in a cluster. Useful for system daemons or agents that need to run on every node.

14. What are Network Policies in Kubernetes?

    • Answer: Network Policies control communication between Pods within a cluster, providing network-level isolation and security.

15. Explain Kubernetes RBAC (Role-Based Access Control).

    • Answer: RBAC allows granular control over access to Kubernetes resources. Users and groups are assigned roles that define their permissions.

16. What is a Pod Disruption Budget (PDB)?

    • Answer: A PDB limits the number of Pods that can be deleted at the same time, ensuring availability during updates or node maintenance.

17. How do you troubleshoot a Kubernetes cluster?

    • Answer: Troubleshooting involves using kubectl commands to check logs, describe resources, check events, inspect resource status and utilize monitoring tools to understand system health.

18. Explain the concept of Kubernetes resource quotas.

    • Answer: Resource quotas limit the amount of resources (CPU, memory, storage) that can be consumed by namespaces, preventing resource exhaustion and ensuring fairness.

19. What are Limit Ranges in Kubernetes?

    • Answer: Limit Ranges define minimum and maximum resource requests and limits for containers within a namespace.

20. How do you monitor a Kubernetes cluster?

    • Answer: Monitoring involves using tools like Prometheus, Grafana, Datadog, or Cloud Monitoring to track metrics, logs, and events, enabling proactive identification of issues.

21. Explain the concept of Kubernetes operators.

    • Answer: Operators automate the management of complex applications on Kubernetes. They use custom controllers to manage the state of the application and handle tasks like deployments, scaling, and upgrades.

22. What are Helm charts?

    • Answer: Helm charts are packages of Kubernetes resources that simplify deployment and management of applications. They define templates for various Kubernetes objects.

23. How do you manage secrets securely in Kubernetes?

    • Answer: Use Kubernetes Secrets to store sensitive data. Employ strong encryption, leverage external secret management solutions, and limit access using RBAC.

24. Explain the concept of Kubernetes auto-scaling.

    • Answer: Auto-scaling automatically adjusts the number of Pods based on resource utilization or custom metrics, ensuring optimal resource usage and application performance.

25. What are some best practices for designing Kubernetes deployments?

    • Answer: Use immutable infrastructure, design for failure, implement proper logging and monitoring, use namespaces effectively, and enforce security best practices (RBAC, network policies).

26. How do you handle different environments (dev, test, prod) in Kubernetes?

    • Answer: Use separate namespaces for each environment to isolate resources and configurations. Employ different configuration values using ConfigMaps and Secrets.

27. Explain the importance of container images in Kubernetes.

    • Answer: Container images are the foundation of Kubernetes deployments. They package applications and their dependencies into portable, consistent units for efficient deployment and scaling.

28. How do you ensure high availability in a Kubernetes cluster?

    • Answer: Deploy multiple master nodes, utilize etcd replication, configure high-availability for worker nodes, and use strategies like replication controllers or stateful sets.

29. What are the different types of Kubernetes storage?

    • Answer: Kubernetes supports various storage types, including local storage, cloud-provider storage (e.g., GCS, AWS EBS), network-attached storage (NAS), and more.

30. Describe how to use kubectl to manage Kubernetes resources.

    • Answer: Kubectl is the command-line tool used to interact with a Kubernetes cluster. It allows creating, deleting, updating, and inspecting Kubernetes objects.

31. What is the role of the kube-apiserver?

    • Answer: The kube-apiserver is the central control plane component that exposes the Kubernetes API, allowing users and other components to interact with the cluster.

32. What is etcd and its importance in Kubernetes?

    • Answer: Etcd is a distributed key-value store that acts as the persistent data store for the Kubernetes cluster state.

33. Explain the kube-scheduler's function.

    • Answer: The kube-scheduler is responsible for selecting the optimal node for scheduling new Pods.

34. What is the kubelet's role in Kubernetes?

    • Answer: The kubelet is an agent running on each node that is responsible for managing containers and interacting with the Kubernetes control plane.

35. What is kube-proxy's purpose?

    • Answer: Kube-proxy is a network proxy that runs on each node and implements the Kubernetes service concept.

36. How does Kubernetes handle node failures?

    • Answer: Kubernetes detects node failures and automatically reschedules Pods running on failed nodes to healthy nodes.

37. Explain the concept of liveness and readiness probes in Kubernetes.

    • Answer: Liveness probes check if a container is healthy and should be restarted if unhealthy. Readiness probes determine if a container is ready to receive traffic.

38. Describe different strategies for deploying applications to Kubernetes.

    • Answer: Strategies include rolling updates, blue/green deployments, canary deployments, and recreate deployments.

39. What are some common challenges in managing a Kubernetes cluster?

    • Answer: Challenges include complexity, security, monitoring, cost optimization, and troubleshooting.

40. How do you secure a Kubernetes cluster?

    • Answer: Employ strong authentication and authorization (RBAC), network policies, pod security policies (or pod security contexts), secure container images, and regular security audits.

41. What are the benefits of using Google Kubernetes Engine (GKE)?

    • Answer: GKE offers managed services, autoscaling, integration with other Google Cloud services, high availability, and simplified cluster management.

42. Explain GKE Autopilot.

    • Answer: GKE Autopilot is a fully managed mode where Google manages the node pool, simplifying cluster management and reducing operational overhead.

43. How does GKE handle node upgrades?

    • Answer: GKE automatically handles node upgrades with minimal disruption, ensuring high availability during the upgrade process.

44. Describe GKE's integration with other Google Cloud services.

    • Answer: GKE seamlessly integrates with services like Cloud Storage, Cloud SQL, Cloud Logging, Cloud Monitoring, and others, enabling efficient workflows.

45. How do you manage costs in GKE?

    • Answer: Cost management involves optimizing cluster size, using preemptible VMs, right-sizing nodes, and leveraging autoscaling to avoid unnecessary resource consumption.

46. Explain GKE's support for different Kubernetes versions.

    • Answer: GKE supports multiple Kubernetes versions, allowing users to choose the version that best suits their needs and upgrade strategies.

47. How do you troubleshoot issues in GKE?

    • Answer: Utilize GKE's monitoring tools, Cloud Logging, and Cloud Monitoring, along with kubectl commands to identify and resolve issues.

48. What are some security considerations when using GKE?

    • Answer: Secure cluster configuration, proper RBAC, network policies, regularly updated images, and vulnerability scanning are crucial for GKE security.

49. How do you manage backups and restores in GKE?

    • Answer: Employ strategies like etcd backups, application-level backups, and potentially using external backup solutions for persistent volumes.

50. Explain the concept of GKE node pools.

    • Answer: Node pools are groups of nodes with similar configurations (e.g., machine type, operating system). They allow flexible scaling and management of nodes within a cluster.

51. How do you handle upgrades in GKE node pools?

    • Answer: GKE manages node pool upgrades automatically, but you can control the update strategy (e.g., rolling upgrades) to minimize disruption.

52. Describe GKE's support for different node machine types.

    • Answer: GKE supports various machine types, allowing users to choose the appropriate hardware configuration for their workloads (e.g., CPU, memory, GPU).

53. How do you monitor resource usage in GKE?

    • Answer: Use Google Cloud Monitoring and other monitoring tools to track CPU utilization, memory usage, disk I/O, and network traffic within your GKE cluster.

54. What are some common performance optimization strategies for GKE?

    • Answer: Optimize node sizing, use appropriate persistent storage, tune application settings, ensure efficient networking, and implement proper scaling strategies.

55. Explain how to use GKE's logging capabilities.

    • Answer: Utilize Cloud Logging to collect, analyze, and monitor logs from your GKE applications and cluster components. It offers efficient search and filtering capabilities.

56. How does GKE integrate with Identity and Access Management (IAM)?

    • Answer: GKE uses IAM for granular control over access to cluster resources. IAM roles and permissions define what users and services can do within the cluster.

57. Explain GKE's support for different networking options.

    • Answer: GKE provides different networking options, including VPC networking, allowing you to configure network policies and manage traffic flow within and outside the cluster.

58. How do you manage updates and upgrades in GKE?

    • Answer: GKE simplifies updates using managed upgrades for Kubernetes versions and node pools. You can control the upgrade pace and rollback if necessary.

59. What are the different authentication methods in GKE?

    • Answer: GKE supports various authentication methods, including Google Cloud credentials, service accounts, and other third-party authentication providers.

60. Explain GKE's support for different container registries.

    • Answer: GKE can pull container images from various registries, including Google Container Registry (GCR), Docker Hub, and other private registries.

61. How do you handle networking issues in GKE?

    • Answer: Use Cloud Monitoring and other network monitoring tools, inspect network policies, check pod logs, and use kubectl commands to diagnose and resolve networking problems.

62. What are some best practices for cost optimization in GKE?

    • Answer: Utilize autoscaling, right-size nodes, use preemptible VMs when appropriate, optimize resource requests and limits, and regularly review resource utilization.

63. How do you implement a CI/CD pipeline for GKE?

    • Answer: Integrate GKE with CI/CD tools like Jenkins, GitLab CI, or Cloud Build. Automate container image building, deployment, and testing to achieve continuous delivery.

64. Describe how to use GKE's features for disaster recovery.

    • Answer: Employ strategies like regional clusters, multi-region deployments, backups, and automated recovery procedures to ensure business continuity.

65. Explain how GKE integrates with Istio or other service meshes.

    • Answer: GKE integrates with service meshes like Istio to provide advanced features such as traffic management, observability, and security for microservices.

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