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Exam Tips and Tricks

Recommendations

General tips:

  • 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.

    • In the first workspace - Kubernetes Docu open,
    • in the second workspace - terminal
    • in the third - notepad for note taking

  • 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:

    • "CTRL + SHIFT + C" for copy
    • "CTRL + SHIFT + V" for paste

  • 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.

Checkin process:

  • ID check and camera scan
  • Clean your testing area
  • One monitor
  • Don't stress

Moved to remote desktop environment in June 2022:

  • XFCE, Firefox
  • Expect some lag
  • Multiple terminals and browser tabs allowed
  • Keyboard layout preserved

Copy/paste:

  • Right click menu
  • Ctrl-shift-(c|v)
  • One-click copy from instructions (recommended to avoid typos)
  • Copying from firefox will trigger a warning (and maybe miss a character)

Terminal:

  • kubectl is pre-aliased to k with autocompletion

  • .vimrc is pre-set (no need to remember):

    shiftwidth=2; expandtab=true; tabstop=2

  • vscode and webstorm available as well more here

  • tmux available but not necessary

Miscellaneous recommendations:

  • Use a big screen
  • Hide the PSI top bar
  • Maximize your comfort

Use shortnames and aliases/variables:

  • 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:

    • cm -> configmap
    • pvc -> persistentvolumeclaim

  • 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

Persist Vim settings

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:

  • expandtab - use spaces for tab
  • tabstop - amounts of spaces used for tab
  • shiftwidth - amounts of spaces used during indentation

Use kubectl to view examples

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>

Sample scenarios

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.

Scenario 1: Create resource

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

Scenario 2: Deleting pods without waiting

Save shortcut:

export now="--force --grace-period 0"

Then delete pod podname

k delete pod podname $now

Scenario 3: Temporary pods

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

Useful links that can be opened during exam

API Overview

  • Can be accessed through:

    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:

Resources