Install-cluster-k8s-centos & ubuntu

How to install faster a cluster K8S.

Namespaces

list all existing namespaces

kubectl get namespaces

create a namespace

kubectl create namespace trainning

change default namespace

kubectl config set-context --current --namespace=trainning

verify current namespace name

kubectl config view | grep namespace:

current configuration and used namespace

kubectl config view

Selector -l --selector

get all pods matching the selector

kubectl get pods --selector='run=httpd'

get logs from all pods matching the selector

kubectl logs --selector='run=httpd' kubectl logs -l run=httpd

Resources handling

delete all created resources in all namespaces (let cluster clean)

kubectl delete all --all

delete resources without waiting

kubectl delete po --wait=false

define requests & limits for pod

kubectl run nginx --image=nginx --requests 'cpu=100m,memory=256Mi' --limits='cpu=200m,memory=512Mi'

define service account, a container port and env var for a pod

kubectl run nginx --image=nginx --serviceaccount=myuser --port=66 --env=var1=val1

create ResourceQuota

kubectl create quota myrq --hard=cpu=1,memory=1G,pods=2

annotate resources

kubectl annotate pod nginx1 nginx2 nginx3 description='my description'

remove annotations

kubectl annotate pod nginx{1..3} description-

PODS

Create a YAML file using --dry-run as a skeleton

kubectl run nginx --image=nginx --restart=Never --dry-run=client -n mynamespace -o yaml > pod.yaml

start pod that runs a specific action (adds it to "args" property automatically)

kubectl run busybox --image=busybox --restart=Never -- /bin/sh -c 'i=0; while true; do echo "$i: $(date)"; i=$((i+1)); sleep 1; done'

start pod that runs a specific action (adds it to "command" property automatically)

kubectl run busybox --image=busybox --command --restart=Never -- /bin/sh -c 'i=0; while true; do echo "$i: $(date)"; i=$((i+1)); sleep 1; done'

run command and automatically delete the pod

(--rm should only be used for attached containers, meaning : when using -it)

kubectl run busybox --image=busybox -it --rm --restart=Never -- echo 'hello world'

run pod and label it in one command

kubectl run nginx2 --image=nginx --restart=Never --labels=access=granted --rm -it -- curl http://nginx

show labels for pods or nodes

kubectl get pod/nodes --show-labels

change already set label

kubectl label pod nginx2 app=v2 --overwrite

remove app label from the pods

kubectl label pod nginx1 nginx2 nginx3 app- kubectl label pod nginx{1..3} app-

label pods that have different label values

kubectl label pod -l "type in (worker,runner)" protected=true

change pod image version

kubectl set image pod/ = kubectl set image pod/nginx nginx=nginx:1.7.1

If pod crashed and restarted, get logs about the previous instance

kubectl logs nginx -p kubectl logs nginx --previous

run shell on a pod

kubectl exec nginx --it -- /bin/sh kubectl exec nginx -- ls -la

show pod with a column have the label name ( here app )

kubectl get pod --label-columns=app

Services

create pod AND expose it via a service

kubectl run nginx --image=nginx --restart=Never --port=80 --expose

check endpoints created for exposed pod

kubectl get ep nginx

JOBS

create a job that executes a command

kubectl create job busybox --image=busybox -- /bin/sh -c 'echo hello;sleep 30;echo world'

Deployment

autoscale deployment

kubectl autoscale deploy nginx --min=5 --max=10 --cpu-percent=80

Configmap

create configmap from file

kubectl create cm configmap4 --from-file=kecialKey=config.txt

Various

copy files/directories from pod's container to local folder and vice versa

kubectl cp /:/tmp/foo /tmp/bar kubectl cp /tmp/foo_dir :/tmp/bar_dir -c

kubernetes kubectl autocompletion

source <(kubectl completion bash)

Recreate join command

kubeadm token create --print-join-command