Kubernetes Fundamentals & Orchestration Flashcards

Question 1

What is Kubernetes?

Accepted Answer

An open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. It groups containers that make up an application into logical units for easy management and discovery.

Question 2

What is a Pod in Kubernetes?

Accepted Answer

The smallest deployable unit in Kubernetes. A `Pod` is an abstraction that represents a single instance of a running process in your cluster. It can contain one or more tightly coupled containers (e.g., an application container and a sidecar logging agent) that share storage, network, and a unique IP address.

Question 3

Explain the relationship between a Pod and a Container.

Accepted Answer

A `Pod` is the smallest deployable unit in Kubernetes, and it *contains* one or more containers. While containers are the actual executables, `Pods` provide the environment and resources (network, storage) for these containers to run together as a single application unit.

Question 4

What is a Deployment in Kubernetes?

Accepted Answer

A higher-level abstraction that manages the desired state of a set of identical `Pods`. `Deployments` provide declarative updates for `Pods` and `ReplicaSets`, enabling features like rolling updates, rollbacks, and scaling.

Question 5

What is a ReplicaSet in Kubernetes?

Accepted Answer

A `ReplicaSet` ensures that a specified number of `Pod` replicas are running at any given time. It's typically managed by a `Deployment`, which provides higher-level features like declarative updates and rollbacks. You rarely interact with `ReplicaSets` directly.

Question 6

How do Deployments and ReplicaSets relate?

Accepted Answer

A `Deployment` is a higher-level object that *owns* and manages `ReplicaSets`. When you create a `Deployment`, it automatically creates a `ReplicaSet` to maintain the desired number of `Pods`. `Deployments` handle updates, scaling, and rollbacks by creating new `ReplicaSets` and gracefully transitioning traffic.

Question 7

What is a Service in Kubernetes?

Accepted Answer

An abstract way to expose an application running on a set of `Pods` as a network service. `Services` provide a stable IP address and DNS name for `Pods`, even if the underlying `Pods` are created, deleted, or moved.

Question 8

Explain the `ClusterIP` Service type.

Accepted Answer

The default `Service` type. A `ClusterIP` `Service` exposes the `Service` on an internal IP address within the cluster. It's only reachable from within the cluster, making it suitable for internal services that other `Pods` in the cluster need to access.

Question 9

Explain the `NodePort` Service type.

Accepted Answer

A `NodePort` `Service` exposes the `Service` on each Node's IP at a static port (the `NodePort`). This makes the `Service` accessible from outside the cluster by requesting `:`. It's often used for development or when an external load balancer isn't available.

Question 10

Explain the `LoadBalancer` Service type.

Accepted Answer

A `LoadBalancer` `Service` exposes the `Service` externally using a cloud provider's load balancer. When you create this type of `Service`, Kubernetes provisions an external load balancer, which routes external traffic to the `Service` within the cluster. This is the standard way to expose internet-facing applications.

Question 11

What is a Namespace in Kubernetes?

Accepted Answer

A `Namespace` provides a mechanism for isolating groups of resources within a single Kubernetes cluster. It's like a virtual cluster within the physical cluster, allowing multiple teams or projects to share a cluster without interfering with each other's resources.

Question 12

What is an Ingress Controller in Kubernetes?

Accepted Answer

An `Ingress Controller` is a specialized load balancer for HTTP/HTTPS traffic that provides external access to services in a cluster. It manages `Ingress` resources, which define rules for routing external traffic to specific `Services` based on hostnames or URL paths.

Question 13

What is a ConfigMap in Kubernetes?

Accepted Answer

A `ConfigMap` is an API object used to store non-confidential data in key-value pairs. It allows you to decouple configuration artifacts from image content, making your applications more portable. `ConfigMaps` can be consumed by `Pods` as environment variables, command-line arguments, or files in a volume.

Question 14

What is a Secret in Kubernetes?

Accepted Answer

Similar to `ConfigMaps`, `Secrets` are used to store sensitive information, such as passwords, OAuth tokens, and SSH keys. Kubernetes `Secrets` are base64 encoded by default (not encrypted), so additional security measures like encryption at rest are recommended. They can be mounted as volumes or exposed as environment variables.

Question 15

What is a Persistent Volume (PV) in Kubernetes?

Accepted Answer

A `Persistent Volume` (PV) is a piece of storage in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes. It's a resource in the cluster, independent of any specific `Pod`, that can be mounted by `Pods`.

Question 16

What is a Persistent Volume Claim (PVC) in Kubernetes?

Accepted Answer

A `Persistent Volume Claim` (PVC) is a request for storage by a user. It's a request for a specific size and access mode (e.g., ReadWriteOnce, ReadOnlyMany). A `PVC` consumes `PV` resources. `Pods` use `PVCs` to request storage, abstracting away the underlying storage details.

Question 17

What is the primary purpose of the `kubectl` command-line tool?

Accepted Answer

`kubectl` is the command-line tool for running commands against Kubernetes clusters. It allows you to deploy applications, inspect and manage cluster resources, and view logs.

Question 18

How do you deploy a resource defined in a YAML file using `kubectl`?

Accepted Answer

Use the `kubectl apply -f <filename.yaml>` command. This command creates or updates resources based on the configuration defined in the YAML file.

Question 19

How do you list all `Pods` in the current `Namespace` using `kubectl`?

Accepted Answer

Use the `kubectl get pods` command. To list `Pods` across all `Namespaces`, use `kubectl get pods --all-namespaces`.

Question 20

How do you get detailed information about a specific `Pod` using `kubectl`?

Accepted Answer

Use the `kubectl describe pod <pod-name>` command. This provides comprehensive details including events, status, labels, and resource usage.

Question 21

How do you view the logs of a `Pod`'s container using `kubectl`?

Accepted Answer

Use the `kubectl logs ` command. If a `Pod` has multiple containers, specify the container name: `kubectl logs -c `.

Question 22

How do you scale a `Deployment` to a desired number of replicas using `kubectl`?

Accepted Answer

Use the `kubectl scale deployment --replicas=` command. For example, `kubectl scale deployment my-app --replicas=3`.

Question 23

How do you delete a `Deployment` using `kubectl`?

Accepted Answer

Use the `kubectl delete deployment <deployment-name>` command. This will also delete the associated `ReplicaSet` and `Pods`.

Kubernetes Fundamentals & Orchestration

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