Certified Kubernetes Application Developer (CKAD) 🐬

This repository contains my notes, definitions, tips, sources, and commands that I used to prepare for the Certified Kubernetes Application Developer exam.

REPOSITORY IN PROGRESS ... 🎠 🙋 🚜

About the Certified Kubernetes Application Developer (CKAD)

  pie showData
      title CKAD categories
      "Application Design and Build" : 20
      "Application Deployment" : 20
      "Application Observability and Maintenance" : 15
      "Application Environment, Configuration and Security" : 25
      "Services and Networking" : 20

More information Training Linux Fundation Updated September 28, 2021. You can also check the curriculum

Explore each category

Here there is a summary of each category!

• 🐾 Application Design and Build
• 🐾 Application Deployment
• 🐾 Application Observability and Maintenance
• 🐾 Application Environment, Configuration and Security
• 🐾 Services and Networking

Useful commands

Use the right context always

# List current contexts
kubectl config get-contexts

# Every time before to start the question
kubectl config use-contex <CONTEXTNAME>

# Note: The asterisk represents the current context

Use Alias

# Alias for kubectl
alias k='kubectl'

# This way you can just run k run my-pod --image=nginx $do.
export do="--dry-run=client -o yaml" # Use it: k run ed --image=nginx $do >pod.yaml

# To apply -f
alias ka='kubectl apply -f'
ka pod1.yaml

# Delete a pod with grace period
alias kdp='kubectl delete pod --force'

# kubectl set context
alias kns='config set-context --current --namespace'

Use Completions

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

Basic commands

# To get all the resorces in a namespaces
kubectl get all

# Describe a resource
kubectl describe pod yellow

# Generate a preview without a file
kubectl create namespace test-123 --dry-run=client -o yaml

# "edit" to edit existing resources
kubectl edit pod nginx
kubectl edit deployment app

# "set" to update a version in a pod or deployment
kubectl set image pod/nginx nginx=nginx:latest
kubectl set image pod/nginx nginx=nginx:1.9.1
kubectl set image deployment/nginx nginx=nginx:latest
kubectl set image deployment/nginx nginx=nginx:1.9.1

Log and Debugging

k run --image=busybox bbox -- sh -c 'while true; do date; sleep 3; done '

kubectl logs busybox
# Follow the logs
kubectl logs busybox -f
kubectl logs webapp-1 | grep USER5

# to select the containers
kubectl logs webapp-2 -c
kubectl logs webapp-2 -c simple-webapp
kubectl logs alta3pod | sudo tee ~/opt/answers/mypod.log

# See the error of a pod
kubectl get events | grep -i error
kubectl dev-pod -c log-x | grep WARN > /opt/logs.txt

# To keep watching the logs
kubectl  logs bbox --follow

# Use describe
kubectl describe bbox
kubectl describe mydeploy

# See the event for all the resources
kubectl get events

# Using grep
kubectl get events | grep Schedule

# View control exec
kubectl run --image=busybox bbox -- sh -c 'echo here; sleep 3600'

# Access to the shell inside the pod
kubectl exec -it bbox -- sh
ls
exit

# Check all the deployments in all the namespaces
k get get deploy --all-namespaces

# List pods and services in a single namespace
kubectl -n elastic-stack get pod, svc

# To check for more options
kubectl explain pods --recursive | less
/volumeMounts

# Monitorins
kubectl top node
kubectl top pod

Observability

# Collect failed pods by namespace
kubectl -n qa get events | grep -i 'Liveness probe failed'

#  Check pods in all namespaces with READY = 0
k get pod --all-namespaces | grep -i 0

#  Check Liveness and Readiness status
kubectl describe pod nginx | grep -i liveness
kubectl describe pod nginx | grep -i readiness

# You'll see the error here as well
kubectl get events | grep -i error

# kubectl cp command
kubectl cp busybox:etc/passwd ./passwd

Cheat Sheet

Download in PDF -> Made by Edith Puclla

Tips and Tricks 🎁

From Udemy course with Mumshad Mannambeth

• Attempt all questions
• Don't get stuck on any question
• Get good with YAML
• Use shortcuts/aliases
  • po for Pods
  • rs for RepicaSets
  • deploy for Deployments
  • svc for Services
  • ns for Namespaces
  • netpol for Networking polices
  • pv for Persistent Volumes
  • pvc for PersistentVolumeClaims
  • sa for service accounts

From - Muralidaran shanmugham

• Go through the k8s.io documentation
• Understand all the concepts outlined in the exam curriculum
• Register for courses like Kodekloud
• Time management
  • nano Editor
  • Kubectl alias
  • learn shortcuts
  • alias k='kubectl'
  • k config set-context --namespace=
  • k explain cronjob.spec.jobTemplate --recursive
  • know all the commands => HERE
  • --restart (YAML generator)
  • args: ["-c", "while true; do date >> /var/log/app.txt; sleep 5; done"]
  • args: [/bin/sh, -c, 'i=0; while true; do echo "$i: $(date)"; i=$((i+1)); sleep 1; done']
  • args: ["-c", "mkdir -p collect; while true; do cat /var/data/*> /collect/data.txt; sleep 10; done"]
  • Use of grep:
    • kubectl describe pods | grep --context=10 annotations:
    • kubectl describe pods | grep --context=10 Events:

Be Fast with VIM

Vim Setup

# Open vim
vim ~/.vimrc

# Add these lines
set expandtab     # Use spaces for tab
set tabstop=2     # Amount of spaces used for tab
set shiftwidth=2  # Amount of spaces used during indentation

Tips

# Move the cursor
- Use:
    h -> move to left
    l -> move to right
    j -> move down
    k -> move  up
- Esc + w           -> move word to word, set cursor at the beginning of the word
- Esc + e           -> move word to word, set cursor at the end of the word
# Edit/view/find words or lines
- Esc + DD          -> delete a line
- Esc + o           -> add a new line
- Esc + :set nu     -> to add line numbers
- Esc + dw          -> Delete a word
- Esc + u           -> revert changes
- Esc + /           -> Find a word
* Esc :num + Enter  -> go a specific number  line in a file, example: Esc :22
# Indent several lines
- Shift + v         -> to visual mode and up and down arrows to move the cursor
- Shift + >         -> indentation to the right
- Shift + <         -> indentation to the left
# Copy and paste single line
- Esc + y           -> copy a line
- Esc + p           -> paste the line
# copy and paste several lines
- Esc + V           -> Mark lines, then arrow keys to select several lines
- Esc + y           -> Copy marked lines
- Esc + d           -> Cut marked lines
- Esc + p           -> Past lines

Kubectl Contexts

# List all kubectl context
kubectl config get-context

# Change to cluster
kubectl config set current-context new-context

Bookmarks on Chrome 🔖

• Go to the documentation: https://kubernetes.io/docs/home/
• Select a topic
• Go to specific section of the page
• Set a bookmark
• If you need copy the code, use copy application to clipboard

My Setup (Optional)

# Kubectl Autocomplete
# Bash
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

alias kn='kubectl config set-context --current --namespace '
alias kd='kubectl delete pod --grace-period=0 --force'
alias ka='kubectl apply -f'
export do='--dry-run=client -o yaml'

Resources: 🔔 🔔

Course 📻

• Udemy CKAD preparation -> Mumshad Mannambeth

Kubernetes Documentation 📘

• Kubernetes documentation - bookmarks have to be based in the oficial documentation

Practice ✏️

1. How to Prepare for CKAD and CKA Certification? -> InfraCloud Team

2. Game of Pods A set of fun challenges to learn and practice your skills on Kubernetes

3. Kubernetes CKAD Example Exam Questions Practical Challenge Series -> Kim Wuestkamp

4. Practice Enough With These 150 Questions for the CKAD Exam -> Bhargav Bachina

5. CKAD Exercises Github -> dgkanatsios

6. Kubernetes Network Policy Recipes

7. KillerCoda - Killer Shell CKAD

8. Securing Kubernetes Cluster Networking

9. https://editor.cilium.io/?id=7OubH15V2XjXYXHr

Videos 🎥

1. How to Pass CKA, CKAD with Flying Colors? -> I AM DINUTH

2. How to CRUSH the CKAD Exam! -> Alta3 Research, Inc.

3. Vim Crash Course | How to edit files quickly in CKAD / CKA exam -> The FrontOps Guy

4. Linux Foundation Kubernetes Certifications Now Include Exam Simulator -> killer.sh CKA, CKAD, or CKS simulator