Kubernetes - Container Orchestration & Deployment Flashcards

Question 1

What is Kubernetes?

Accepted Answer

Kubernetes (K8s) is an open-source 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.

Question 2

Why is container orchestration needed?

Accepted Answer

Container orchestration is needed to manage the lifecycle of containers in large-scale deployments. It automates tasks like deployment, scaling, networking, load balancing, health monitoring, and self-healing, which are complex to handle manually for many containers.

Question 3

What is `kubectl`?

Accepted Answer

`kubectl` is the command-line tool for running commands against Kubernetes clusters. It allows you to inspect cluster resources, create, update, and delete components, and view logs.

Question 4

What are YAML manifests in Kubernetes?

Accepted Answer

YAML manifests are declarative configuration files used to define Kubernetes objects (e.g., Pods, Deployments, Services). They specify the desired state of your application and resources, which Kubernetes then works to achieve and maintain.

Question 5

Define a Kubernetes `Pod`.

Accepted Answer

A `Pod` is the smallest deployable unit in Kubernetes. It represents a single instance of a running process in your cluster. A `Pod` encapsulates one or more containers (e.g., Docker containers), storage resources, a unique network IP, and options that govern how the containers should run.

Question 6

What is a Kubernetes `Node`?

Accepted Answer

A `Node` is a worker machine in Kubernetes, which can be a VM or a physical machine. Each `Node` contains the necessary services to run `Pods`, including the Kubelet (agent), Kube-proxy (network proxy), and a container runtime (e.g., containerd).

Question 7

What is a Kubernetes `Cluster`?

Accepted Answer

A Kubernetes `Cluster` is a set of `Nodes` that run containerized applications. It consists of at least one master node (control plane) and multiple worker nodes. The control plane manages the worker nodes and the `Pods` in the cluster.

Question 8

Define a Kubernetes `ReplicaSet`.

Accepted Answer

A `ReplicaSet` ensures that a specified number of `Pod` replicas are running at any given time. If a `Pod` fails, the `ReplicaSet` automatically creates a new one. It's typically managed by a `Deployment`.

Question 9

Define a Kubernetes `Deployment`.

Accepted Answer

A `Deployment` provides declarative updates for `Pods` and `ReplicaSets`. It allows you to describe the desired state of your application and automatically handles creating, updating, and scaling `Pods`. `Deployments` are the recommended way to manage stateless applications.

Question 10

How do `Deployments` facilitate rolling updates?

Accepted Answer

`Deployments` facilitate rolling updates by gradually replacing old `Pod` instances with new ones, ensuring zero downtime. They manage the creation of new `ReplicaSets` for the new version and scale down the old `ReplicaSet` as new `Pods` become ready.

Question 11

Explain Kubernetes' self-healing capabilities.

Accepted Answer

Kubernetes offers self-healing by automatically restarting failed containers, replacing dead `Pods`, rescheduling `Pods` on healthy `Nodes` if a `Node` fails, and killing `Pods` that don't respond to user-defined health checks.

Question 12

What is a Kubernetes `Service`?

Accepted Answer

A `Service` is an abstract way to expose an application running on a set of `Pods` as a network service. It provides a stable IP address and DNS name for a group of `Pods`, abstracting away the dynamic nature of `Pod` IPs.

Question 13

Explain the `ClusterIP` Service type.

Accepted Answer

A `ClusterIP` `Service` exposes the `Service` on an internal IP in the cluster. It's only reachable from within the cluster. This is the default `Service` type and is used for internal communication between services.

Question 14

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 to expose a service behind a load balancer.

Question 15

Explain the `LoadBalancer` Service type.

Accepted Answer

A `LoadBalancer` `Service` exposes the `Service` externally using a cloud provider's load balancer. The cloud provider automatically provisions a load balancer that routes external traffic to the `Service` `Pods`. This is suitable for production environments requiring external access.

Question 16

What is a Kubernetes `Namespace`?

Accepted Answer

A `Namespace` provides a mechanism for isolating groups of resources within a single Kubernetes cluster. It's used to divide cluster resources between multiple users or teams, providing scope for names and resource quotas.

Question 17

What is a Kubernetes `ConfigMap`?

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 applications more portable. `Pods` can consume `ConfigMaps` as environment variables, command-line arguments, or as files in a volume.

Question 18

What is a Kubernetes `Secret`?

Accepted Answer

A `Secret` is an object used to store sensitive information, such as passwords, OAuth tokens, and SSH keys. It provides a more secure way to store and manage sensitive data than `ConfigMaps`, though it's still base64 encoded by default and requires additional encryption for true security.

Question 19

What is a Kubernetes `Volume`?

Accepted Answer

A `Volume` is a directory, potentially with some data in it, that is accessible to the containers in a `Pod`. Kubernetes `Volumes` have the same lifetime as the `Pod` that encloses them, but their data persists across container restarts within that `Pod`.

Question 20

Define a Kubernetes `DaemonSet`.

Accepted Answer

A `DaemonSet` ensures that all (or some) `Nodes` run a copy of a `Pod`. As `Nodes` are added to the cluster, new `Pods` are added to them. As `Nodes` are removed, those `Pods` are garbage collected. `DaemonSets` are useful for deploying cluster-level services like logging agents or monitoring agents.

Question 21

Define a Kubernetes `StatefulSet`.

Accepted Answer

A `StatefulSet` is used to manage stateful applications. It provides guarantees about the ordering and uniqueness of `Pods`, stable network identifiers, and stable persistent storage. It's suitable for databases or other applications requiring stable identities and persistent data.

Question 22

How do Pods communicate within a Kubernetes cluster?

Accepted Answer

Pods communicate within a cluster via their unique IP addresses. Kubernetes networking ensures that each `Pod` gets its own IP address and that `Pods` on different `Nodes` can communicate without NAT. This is typically achieved through a Container Network Interface (CNI) plugin.

Question 23

Briefly explain persistent storage considerations in Kubernetes.

Accepted Answer

For persistent storage, Kubernetes uses `PersistentVolumes` (PVs) and `PersistentVolumeClaims` (PVCs). A `PV` is a piece of storage in the cluster, while a `PVC` is a request for storage by a user. This abstraction allows `Pods` to request storage without knowing the underlying infrastructure details, ensuring data persistence beyond a `Pod`'s lifecycle.

Kubernetes - Container Orchestration & Deployment

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