Mastering the Essentials: Top Interview Questions on Docker and Kubernetes

 

1.What is Docker, and how does it work?

Docker is a platform that enables developers to create, deploy, and run applications in containers. Containers are lightweight, portable units that package software and its dependencies, ensuring consistent execution across environments.

2. What are Docker images, and how are they different from containers?

A Docker image is a lightweight, standalone, and executable package that includes everything needed to run an application. A container is a running instance of a Docker image, created by using the docker run command.

3. What is a Dockerfile?

A Dockerfile is a text file that contains instructions to assemble a Docker image. It defines the environment in which the application runs, including the base image, dependencies, and commands.

4. What is Docker Compose, and how is it used?

Docker Compose is a tool for defining and running multi-container Docker applications. It uses a YAML file (docker-compose.yml) to configure services, networks, and volumes, allowing you to manage multiple containers easily.

5. What is a Kubernetes Pod?

A Kubernetes Pod is the smallest deployable unit in Kubernetes, representing a single instance of a running process in a cluster. Pods can contain one or more containers that share the same network namespace and storage.

6. How do Kubernetes Deployments work?

Kubernetes Deployments define the desired state of a pod or a set of pods and manage updates to those pods. Deployments ensure that the correct number of pods are running and handle rolling updates and rollbacks.

7. What is a Kubernetes Service?

A Kubernetes Service is an abstraction that defines how to access a set of Pods. It can expose a Pod or set of Pods either within the cluster (ClusterIP), externally (NodePort, LoadBalancer), or through an ingress controller.

8. What is a namespace in Kubernetes?

A namespace is a mechanism to divide cluster resources between multiple users or teams. Namespaces allow you to create isolated environments within a Kubernetes cluster, enabling easier resource management and organization.

9. What is the role of the kube-scheduler?

The kube-scheduler is a component of the Kubernetes control plane responsible for assigning Pods to nodes based on factors like resource availability, affinity/anti-affinity rules, and taints/tolerations.

10. How does Kubernetes handle container networking?

Kubernetes uses a flat networking model, where every Pod has its own IP address, and containers within a Pod share the same network namespace. Kubernetes supports different networking plugins, such as Calico and Flannel, to manage container-to-container communication.

11. What is the difference between Docker Swarm and Kubernetes?

• Docker Swarm: Docker's native clustering and orchestration tool, simpler and integrated with Docker.
• Kubernetes: A robust, feature-rich orchestration system that supports scaling, self-healing, service discovery, and rolling updates, but with a steeper learning curve.

12. What is the use of ConfigMaps and Secrets in Kubernetes?

• ConfigMaps: Store configuration data as key-value pairs that can be consumed by Pods.
• Secrets: Store sensitive data like passwords, tokens, or keys. Secrets are encrypted and should be used for secure data management.

13. How do you manage persistent storage in Kubernetes?

Kubernetes uses Persistent Volumes (PV) and Persistent Volume Claims (PVC) to manage storage. A PV is a resource in the cluster that provides storage, and a PVC is a request for storage by a Pod. Kubernetes dynamically binds PVs to PVCs.

14. What is Helm, and how does it simplify Kubernetes management?

Helm is a package manager for Kubernetes that allows developers to define, install, and upgrade applications using charts (pre-configured templates). It simplifies deploying complex Kubernetes applications and managing updates.

15. What are Kubernetes Ingress Controllers?

Ingress controllers manage external access to services within a Kubernetes cluster. Ingress resources define how traffic is routed to services based on rules such as hostnames and paths. Ingress controllers like Nginx or Traefik are responsible for handling and routing traffic.