Kubernetes Fundamentals

Question 1

What are Kubernetes Resources?

Answer 1

Resources are simply Objects of a certain type (ex. Pods, Services, Deployments, etc.) in the K8s API. You interact with the Cluster by creating and modifying these K8s Objects

Question 2

What is a Kubernetes Pod?

Answer 2

The most basic resource in K8s, represents a group of one or more containers

Question 3

What is a Kubernetes Service?

Question 4

What is a Kubernetes Deployment?

Answer 4

Provides a way to declaratively update Pods and ReplicaSets, great for scaling stateless apps and uses RollingUpdate by default for zero downtime updates

Question 5

What is the command to list all available resource types within the cluster?

Answer 5

$ kubectl api-resources

Question 6

How can you get documentation about a certain resources type in K8s?

Answer 6

$ kubectl explain

Question 7

How can you define your own custom resource types?

Answer 7

CustomResourceDefinition

Question 8

What is a ReplicaSet?

Answer 8

Ensures a given # of Pods are running at any given time - it’s a copy of a Pod to ensure resiliency

Question 9

How do you imperatively create a deployment, what command would you use?

Answer 9

$ kubectl create deployment <deploy> --image=<image></image></deploy>

Question 10

What is a StatefulSet?

Answer 10

Similiar to Deployments, but for Stateful Pods, they maintain order and stick identity (same Pod name, networking, hostname, etc.) and it requires a Headless Service to go alongside it

Question 11

What is a DaemonSet?

Answer 11

Guarantees that a replica Pod will run on each Node as they join the cluster. You can use filtering to pick and choose which nodes, but good for deploying vendor software (ex. Twistlock)

Question 12

What is a Job?

Answer 12

A job will reliably run containerized task to completion

Question 13

What is a CronJob?

Answer 13

This will create and Run Jobs repeatedly according to a schedule

Question 14

What is the Control Plane?

Answer 14

A set of software components that manage worker Nodes and Pods, it’s not just a server

Question 15

What are Worker Nodes?

Answer 15

Servers that host Pod and run container workloads

Question 16

List all of the Control Plane components

Answer 16

API Server, etcd, Scheduler, Controller Manager, and Cloud Controller Manager

Question 17

List all of the Worker Node components

Answer 17

kube-proxy, kubelet, Container Runtime,

Question 18

What is the API Server?

Answer 18

This is the backbone for all things Kubernetes and is a control plane component. Used to communicate and interact with the Cluter.

Question 19

What is etcd?

Answer 19

Reliable Object Storage - a data store for the API Server. API Server stores data about the state of the cluster

Question 20

What is the Scheduler?

Answer 20

A CP component that watches for new Pods that haven’t been assigned to a worker node. Selecting a Node for a Pod is called “Scheduling”