kubectl explain Pods.spec.containers --recursive
kubectl run # without flag creates a deployment
kubectl run — restart=Never #Creates a Pod
kubectl run — restart=OnFailure #Creates a job
kubectl run — restart=OnFailure — schedule=”* * * * *” # Creates a cronjob
alias k=‘kubectl’
alias kgp=‘kubectl get pods’
alias kgd=‘kubectl get deployment’
alias kgs=‘kubectl get service’
alias kga=‘kubectl get all’
alias kgaa=‘kubectl get all -A’
alias kdp=‘kubectl delete pod --grace-period=0 --force’
alias kcf=‘kubectl create -f’
alias kaf=‘kubectl apply -f’
export drc=’–dry-run=client -o yaml’
echo $SHELL
source <(kubectl completion bash)
alias k=kubectl
complete -F __start_kubectl k
export do="–dry-run=client -o yaml"
export fg="–force --grace-period=0"
export kc=’‘kubectl config set-context $(kubectl config current-context) --namespace’’
vi ~/.vimrc
set ts=2 sw=2 expandtab ruler
set backspace=indent,eol,start
Here is how we could get only that pod that uses most CPU:
k top pod -n kube-system --sort-by=cpu | head -2 | tail -n 1
Posting in this thread directly because we’ve had to remove posts / ban users after posting in here several times now.
This is not a place for exam notes. You cannot use this on the CKA/CKAD. Posting such content will result in an immediate ban.
Posts containing exam content from the CKA/CKAD will be immediately removed and the information passed to the CNCF with a likely result of having your certificate being revoked.
hello
it was not my intention to use the forum improperly.
I have consulted your forum a lot for the study of k8s. I apologize if I made you work today to remove posts and utilities.
I hope you won’t delete this user account, because it has been very useful to me to study and discover things, and I would like to consult it and vice-versa in an active way.
Good work and good life
Berardino
I suggest also for example pod
Kubect explain pod --recursive | less
To see the structure or
Kubectl explain pod --recursive | grep -I version
Too looking for the value of APIversion for example
We put together this kubectl cheat sheet, thought it might be helpful to learn some initial tips and tricks:
I practice a lot in Katacoda (it’s a temporary - 60mins - workspace). That’s why every time I need to download the latest kubectl client and set up .bashrc and .vimrc. Pasting those lines saves time:
curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl
chmod +x ./kubectl
sudo mv ./kubectl $(which kubectl)
echo 'source <(kubectl completion bash)' >> ~/.bashrc
echo 'alias k=kubectl' >> ~/.bashrc
echo 'complete -F __start_kubectl k' >> ~/.bashrc
source .bashrc
echo 'set nu ts=2 sw=2 expandtab ruler' > ~/.vimrc
echo 'set backspace=indent,eol,start' >> ~/.vimrc
source ~/.vimrc
export do="--dry-run=client -oyaml"
export now="--grace-period=0 --force"I find useful the below lines:
alias k=kubectl
source <(k completion bash)
source <(k completion bash | sed s/kubectl/k/g)
vi ~/.vimrc
autocmd FileType yaml setlocal ts=2 sts=2 sw=2 expandtab ruler incsearch
set number
set ignorecase
set backspace=indent,eol,start
set cursorline
set list
If you explain a little more about these things. It will help a lot to us.
Thank you Aydarsh
I found very useful your set of tricks and tips and he has helped me a lot to define my own set and to figure it out the way I faced the exam.
I am sharing some of my thoughts on them.
First of all, I prefer to deal with a limited set of alias, easy to remember and that saves a lot of time. I also look for the very basic configuration of my editor (line number, tabs as spaces, etc). Choose the ones you think would help and practice with them all the time. I am listing below the ones that were useful for me.
{
echo "set tabsize 2" | tee -a ~/.nanorc
echo "set tabstospaces" | tee -a ~/.nanorc
echo "set linenumbers" | tee -a ~/.nanorc
alias k=kubectl
alias kn='k config set-context --current --namespace'
alias kcc='k config get-contexts'
alias kd='k --force --grace-period=0 delete po'
alias ka='k get all'
alias kaa='k get all -A'
alias kcf='k create -f'
. <(kubectl completion bash)
complete -F __start_kubectl k
export do='-o yaml --dry-run=client'
export KUBE_EDITOR=nano
}
When time is an important variable to consider, and you are like me --not a born in the terminal guy-- Nano is your editor, here the most recommended shortcuts to practice with.
Remember you can always use F1/^G
Goto, Find, Replace
| ^_ (M-G) | Go to line and column number |
| ^W (F6) | Search forward for a string or a regular expression |
| ^\ (M-R) | Replace a string or a regular expression |
Copy and paste
| ^K (F9) | Cut current line (or marked region) and store it in cutbuffer |
| ^U (F10) | Paste the contents of cutbuffer at current cursor position |
Region
| M-6 (M-^) | Copy current line (or marked region) and store it in cutbuffer |
| M-A (^6) | Mark text starting from the cursor position |
Formating
| M-} (Tab) | Indent the current line (or marked lines) |
| M-{ (Sh-Tab) | Unindent the current line (or marked lines) |
Reading, Writing, Exiting
| ^X (F2) | Close the current buffer / Exit from nano |
| ^O (F3) | Write the current buffer (or the marked region) to disk |
| ^R (Ins) | Insert another file into current buffer (or into new buffer) |
I will just add to the connectivity commands recommended by aydarsh, the ones I think should help to create test pod on-demand or connect quickly to running containers
wget -O- http://10.44.0.1:80
curl http://10.44.0.1 80
nc -vz 10.44.0.1 80
k exec -it pod -- [command]
k run bash -it --image=bash --rm -- [command]
My config, if anyone interested:
.vimrc
set nu tabstop=2 shiftwidth=2 expandtab
.bashrc
source <(kubectl completion bash)
alias k=kubectl
complete -F __start_kubectl k
export do="-o yaml --dry-run=client"
export gf="–grace-period=0 --force"
alias kn='kubectl config set-context --current --namespace ’
here is my .vimrc file, hope it will be helpful.
syntax enable
set tabstop=2 " number of visual spaces per TAB
set softtabstop=2 " number of spaces in tab when editing
set expandtab " tabs = spaces
set number " show line numbers
set cursorline " highlight the current line
set showcmd " show command in bottom bar
filetype indent on " load filetype specific indent files in ~/.vim/indent/*.vim
set wildmenu
set lazyredraw
set showmatch " show matches of {} [] ()
set incsearch " search as characters are entered
set hlsearch " highlight matches
set ignorecase " ignore upper/lower case when searching
let mapleader = "," " leader is comma
" turn off search highlight, mapping to ,<space>
nnoremap <leader><space> :nohlsearch<CR>
set backspace=indent,eol,start " allows backspace to delete words
Enable the kubelet autocomplete
source <(kubectl completion bash) # setup autocomplete in bash into the current shell, bash-completion package should be installed first.
echo "source <(kubectl completion bash)" >> ~/.bashrc # add autocomplete permanently to your bash shell.
alias k=kubectl
complete -F __start_kubectl k
Also some commands I found tricky:
Core Concepts:
kubectl get pods -o=jsonpath="{.items[ * ][‘metadata.name’, ‘metadata.namespace’]}" <- list all pod with name and namespace
kubectl set image pod/nginx nginx=nginx:1.17.1
kubectl get po nginx -o jsonpath=’{.spec.containers[\ * ].image}{"\n"}’
kubectl logs busybox -p <- check previous logs
kubectl exec -it busybox – wget -o- --timeout=3
kubectl get po nginx --v=7
kubectl get po -o=custom-columns=“POD_NAME:.metadata.name, POD_STATUS:.status.containerStatuses[ ].state”
kubectl get pods --sort-by=.metadata.name
Configuration:
kubectl get secret mysecret2 -o jsonpath=’{.data.username}{"\n"}’ | base64 -d
Multi-Container Pods:
apt-get update && apt-get install -y curl
curl localhost:30080 -m 3
kubectl top pod busybox --containers
Observability:
kubectl explain Pod.spec.containers.livenessProbe
kubectl explain Pod.spec.containers.readinessProbe
kubectl get events --sort-by=.metadata.creationTimestamp > file.log
kubectl logs --follow hello
kubectl top pod --all-namespaces | sort --reverse --key 3 --numeric | head -3 > cpu-usage.txt
Pod Design:
kubectl get pods --show-labels
kubectl label pod/nginx-dev3 env=uat --overwrite
k label po --all env-
kubectl get pod nginx{1…3}
kubectl annotate pod nginx-dev{1…3} name=webapp
k rollout status
history [–revision]
undo [–to-revision]
pause
resume
kubectl autoscale deploy webapp --min=10 --max=20 --cpu-percent=85
kubectl get hpa
spec: <- job spec
completions: 10
parallelism: 10
kubectl create cronjob date-job --image=busybox --schedule="*/1 * * * *" - every minute
Services and Networking:
kubectl run nginx --image=nginx --restart=Never --port=80 --expose <- expose creates clusterip automatically 
kubectl expose deploy foo --port=6262 --target-port=8080 <- match all pods with label app=foo
State persistance:
cat /etc/passwd | cut -f 1 -d ‘:’ > /etc/foo/passwd <- copies first column from file with : delimiter
Reposting this further down in the thread because it continues to be a problem:
Posting in this thread directly because we’ve had to remove posts / ban users after posting in here several times now.
This is not a place for exam notes. You cannot use this on the CKA/CKAD. Posting such content will result in an immediate ban.
Posts containing exam content from the CKA/CKAD will be immediately removed and the information passed to the CNCF with a likely result of having your certificate being revoked.
If this continues, we’ll move to lock the thread.
Couple things I have found useful. Using ‘-h’ with a command. Provides a great source for examples.
kubectl create -h
Another is using labels with logs. Especially nice if you have a bunch of pods using the same label
kubectl -n <namespace> logs -l label=somenameYou can use this also
set expandtab
set tabstop=2
set shiftwidth=2
set autoindent
set smartindent
set bg=dark
set nowrap
set paste
Hi Krzysztof_Tkacz,
I saw this syntax being used in a few tutorials.
kubectl get pod nginx{1…3}
but I can’t find anything similar in kubectl official documents.
Do you have any reference to some docs that explain it more? I was wondering what other things you can do with this type of expansion.
Good question , probably I found this one in some training. I think it could be good stackoverflow question.