Adopt Killer Shell’s tips regarding .bashrc and env variables (the vi settings were fine on my exam, but check anyway)
The PSI Exam environment looks the same as Killer Shell, so use Killer Shell to adopt a fast workflow.
The desktop shows several workspaces in the top right corner, use them.
The “copy” button on the tasks page might not work in the real exam. You have to type in everything manually.
Use “CTRL + R” for reverse search of your commands - this is really handy for context switching and other stuff.
In the Linux terminal, you can try:
To copy texts from the K8s documentation, select text, right click, copy (don’t use the web function in the header of the templates to copy, as this doesn’t work with indentations).
If you need to select a bunch of text, make a little selection at the top, scroll to the end and shift click to where you want to expand the selection to.
First click through all tasks and filter out all > 10% questions, do these first, then all > 5% and finally the rest
Write down completed tasks in your notes, because PSI Browser doesn’t have such a function
I won’t give any details here, but there could be tasks that require a longer waiting time, use this time to open a second tab in the terminal and do a task that is very easy for you in parallel
Check your results - this assumes you know how to check. Test this at Killer Shell and you’ll be fast in the exam.
| Ctrl-shift-(c | v) |
.vimrc is pre-set (no need to remember):
shiftwidth=2; expandtab=true; tabstop=2
Enable kubectl auto-completion:
source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc
Never type out a full resource name if you can help it, example:
Useful aliases:
## create yaml on-the-fly faster
export do='--dry-run=client -o yaml'
## create/destroy from yaml faster
alias kaf='k apply -f '
alias kdf='k delete -f '
## namespaces (poor man's `kubens`)
export nk='-n kube-system'
export n='-n important-ns' # set this as needed
## destroy things without waiting
export now='--grace-period 0 --force'
## Other aliases
alias k=kubectl
alias kgp="k get pod"
alias kgd="k get deploy"
alias kgs="k get svc"
alias kgn="k get nodes"
alias kd="k describe"
alias kge="k get events --sort-by='.metadata.creationTimestamp' |tail -8"
## For dry-run
export do="--dry-run=client -o yaml"
Check all shortnames with:
k api-resources
Create the ~/.vimrc file.
vim ~/.vimrc
set expandtab
set tabstop=2
set shiftwidth=2
This now becomes the default Vim settings when you open a terminal:
kubectl run --help
Create and run a particular image in a pod.
Examples:
# Start a nginx pod.
kubectl run nginx --image=nginx
# Start a hazelcast pod and let the container expose port 5701.
kubectl run hazelcast --image=hazelcast/hazelcast --port=5701
# Start a hazelcast pod and set environment variables "DNS_DOMAIN=cluster" and "POD_NAMESPACE=default" in the
container.
kubectl run hazelcast --image=hazelcast/hazelcast --env="DNS_DOMAIN=cluster" --env="POD_NAMESPACE=default"
# Start a hazelcast pod and set labels "app=hazelcast" and "env=prod" in the container.
kubectl run hazelcast --image=hazelcast/hazelcast --labels="app=hazelcast,env=prod"
# Dry run. Print the corresponding API objects without creating them.
kubectl run nginx --image=nginx --dry-run=client
# Start a nginx pod, but overload the spec with a partial set of values parsed from JSON.
kubectl run nginx --image=nginx --overrides='{ "apiVersion": "v1", "spec": { ... } }'
# Start a busybox pod and keep it in the foreground, don't restart it if it exits.
kubectl run -i -t busybox --image=busybox --restart=Never
# Start the nginx pod using the default command, but use custom arguments (arg1 .. argN) for that command.
kubectl run nginx --image=nginx -- <arg1> <arg2> ... <argN>
# Start the nginx pod using a different command and custom arguments.
kubectl run nginx --image=nginx --command -- <cmd> <arg1> ... <argN>
You can use dry run to generate a basic yaml file, then make any necessary changes on that file, and then use the modified file to create the required resources.
Create an nginx pod, set the request memory to 1M and the CPU to 500m can be solved with the following commands:
Save a shortcut:
export do="--dry-run=client -o yaml"
Then we can do the following:
k run nginx --image=nginx --dry-run=client -oyaml > pod.yaml
vi pod.yaml
k create -f pod.yaml
From this:
kubectl run nginx --image=nginx --dry-run=client -o yaml > pod.yml
Instead we can just run this:
k run nginx --image=nginx $do > pod.yml
Save shortcut:
export now="--force --grace-period 0"
Then delete pod podname
k delete pod podname $now
Create a busybox pod, run wget command in it to test a k8s service created in the previous step.
Since this is only for testing, we don’t need the pod to persist after it has completed running wget. We cna use the -rm option which will delete the pod immediately after running the specified command.
$ k run busybox --image=busybox -it -rm -- sh
If you don't see a command prompt, try pressing enter.
/ # wget -O- 172.17.254.255
API Overview
https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.27/
or simply go to site then Documentation > Reference > One-page API Reference for Kubernetes v1.27
kubernetes.io
Others: