Orchestration: Kubernetes Flashcards by StevSecOps

What to all install when installing K8s?

kubectl
K8s Master
Worker node agents

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How to run a pod using the soon to be deprecated method?

kubectl run mywebserver –image=nginx

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How to exec into a pod?

kubectl exec -it mywebserver-xyz – bash

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How to delete a pod?

kubectl delete pod mywebserver-xyz

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What is an object?

Object is a record of intent, once created K8s will work to ensure that the object exists.

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How to create a K8s object via YAML configuration file?

kubectl apply -f file.yaml

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How to delete a K8s object via YAML configuration file?

kubectl delete -f file.yaml

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What is a the purpose of a ReplicaSet?

To maintain a set of replica pods

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What are the two states of pods in a ReplicaSet?

Current and Desired

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How to view the labels of pods?

kubectl get pods –show-labels

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What does the “selector / matchLabels” section do in ReplicaSets?

Determines which label is used to count the number of current pods for the ReplicaSet

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What is the main difference between a ReplicaSet and a Deployment?

Deployment sits on top of ReplicaSets, with features like rolling out updates and rolling back.

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How does a Deployment rollout changes?

Creates a new ReplicaSet, once running, deletes old ReplicaSet.

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Equivalent K8s command for docker inspect?

kubectl describe resource_type resource_name

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How to get the rollout history for a deployment?

kubectl rollout history deployment.v1.apps/my_deployment

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How to get information about a specific deployment revision?

kubectl deployment history deployment.v1.apps/my_deployment –revision=1

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What is the default max unavailable pods and maximum surge during a deployment rollout?

25%

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For deployment rollout, which parameter determines the max number of pods that can be scheduled above the original number of pods?

maxSurge

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For deployment rollout, which parameter determines the maximum amount of pods that can be unavailable during the deployment?

maxUnavailable

Two different ways of getting information about a resource (pod/deployment/replicaset/etc)

kubectl get pod my_pod -o yaml

kubectl describe pod my_pod

How to create a new basic K8s secret with a literal value?

kubectl create secret generic my_secret –from-literal=dbpass=password123

How to create a new basic K8s secret from a file?

kubectl create secret generic my_secret –from-file=./file.txt

What are two approaches to make secrets available to Pods?

Environment Variables

Volumes

How to create a ConfigMap

kubectl create configmap my_config –from-literal=memory=2048m

What does a Kubernetes service do?

Acts as a load balancer and a single point of contact for pods to communicate to downstream pods

What are the four types of K8s services?

ClusterIP NodePort LoadBalancer ExternalName

What are the 3 characteristics of ClusterIP service?

Internal Cluster IP address is assigned to the service Only reachable from inside the cluster Default service type

What is the NodePort service?

K8s opens a random port on each worker node | Is accessible over the internet

What are the 4 networking considerations for K8s?

1. Container to container 2. Pod to Pod 3. Pod to Service 4. Internet to Service

How does container to container communication occur in K8s Networking Model?

Using localhost and port numbers for other containers in the same pod

How does pod to pod communication occur in K8s Networking Model?

Virtual interfaces on the pod communicating via a bridge

How does pod to service communication occur in K8s Networking Model?

Service creates an IP or DNS endpoint which can be used to route traffic to

How does internet to service communication occur in K8s Networking Model?

Using an Ingress controller (like Traefik)

What is a Liveness Probe?

Used to detect the state (healthy/unhealthy) of an application, and take actions such as restarting

What is Readiness Probe?

A healthcheck that will wait for new pods before serving traffic or trying to restart the pod

How does a Readiness Probe differ from Liveness Probe?

Liveness is to know when to restart a container | Readiness is to know when it can start accepting traffic

What is a K8s DaemonSet?

Similar to docker global replicated services. One pod per node, and new nodes get the pod

What are Taints?

Used to repel pods from a specific node ie, prevents a pod from running on a specific node

What is a Toleration?

It's a pass for a pod to be deployed to a tainted node

What is the command to taint a node?

kubectl taint node node_name key=value:NoSchedule

What is the purpose of the key and value in the taint command?

Used to issue a toleration for a pod for a specific taint key:value

What is a Selector in K8s?

Used to filter on specific labels

How to get all pods with the label of env=prod?

kubectl get pods -l env=prod

What is a resource Request?

The amount of resources that a pod is guaranteed to get

What is a resource Limit?

Makes sure that the resource does not go above a specific value

How to view the Requests and Limits for a specific node?

kubectl describe node my_node

What are the three states of Requests/Limits?

Guaranteed Burstable Best Effort