Kubernetes - Exam-tips-CKA

 Exam-tips-CKA

1. BookMark the links
kubernetes cheat sheel
init containers
Hints for CKA exam
manage TLS certificates in a cluster
TLS bootstrapping
Authenticating with bootstrap tokens
PKI certificates and requirements
HostPath configure a pod to use persistentvolume for storage
persistent volumes
Rolling update on a DaemonSet
secrets
field selectors
Node not ready
troubleshooting kubelet
Operating etcd clusters for kubernetes
drain a node while respecting the poddisruptionBudget
ClusterIP
Services
daemonSet
kubeadm

2. Create alias
alias egrep='egrep --color=autp"
alias fgrep='fgrep --color=auto'
alias grep=grep --color=auto'
alias kc=kubectl
alias kd='kubectl get deploy'
alias kp='kubectl get pod'
alias ks='kubectl get svc'
alias ls='ls --color=auto'
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'

3. Know how to generate and edit yaml
$ kc run nginx --image=nginx --restart=Never --dry-run -oyaml > pod.yaml
$ vi pod.yaml
$ kc create -f pod.yaml

4. Practice
- know your kubectl commands
- Practice on tmux
  - it will allowed on exam

how to use it?
at the command prompt, type
$ tmux
you will get a new command prompt. You are inside tmux shell.

Type CTRL+B " (Press control B + double quote)


4. Opening tab on the browser
you are allow to open two browser tabs
one for exam and another have your k8s official with all book marks

5. In the exam, remember to
- use the built in notepad
- know which of the six cluster  you are in
- Read the questions carefully.
- Time based questions and question worth different on each question.
- If you don't know the question, move forward (manage your time)


Application lifecysle management
- Create deployment from  yaml
- How to scale up and down deployments
- Perform rollouts and rollbacks
- CronJobs
- ConfigMaps

$ kc create deploy webapp1 --image=nginx:1.16-alpine-perl --dry-run -o yaml > webapp1.yaml
$ cat webapp1.yaml

review the document
you can make changes based on requirement
say replicas or version

now create
$ kc create -f webapp1.yaml
> kd
> kp
all pods running now.

we can modify this yaml file
> kc -o wide
> cp webapp1.yaml webapp2.yaml

> vi webapp2.yaml

go to the image section and change it to 1:18

now, you can roll out
> kd -o wide
review the version running under images
now, you can apply to upgrade

> kc apply -f webapp2.yaml
$ kc -o wide
you will see the upgraded version
$ kc rollout status deploy webapp1
$ kc rollout history deploy webapp1
$ kc rollout undo deploy webapp1
> kc -o wide
we rollback  back again with old pod version

> kc get pods
> kc apply -f webapp2.yaml
> kc get pods

you will see terminating pods and creating new one

lets try again with undo
> kc rollout undo deploy webapp1

old pod terminated and new pods brought up

They are running

> kp
> kd -> deployment

scale up
two ways to do it

1. edit the yaml file and change replicas
$ vi webapp1.yaml
$ kc apply -f webapp1.yaml

2. kubectl scale
> kc scale --replicas=10 deploy webapp1
$ kp -w

you will see new pods being created
$ kd

scale down
> kc scale --replicas=2 deplpy webapp1

now down to 2 pods in this deployment
$ kd

So far, we completed
- create yaml file
- scaling up deployments
- performs rollours and rollbacks

configMap - > what is it?

Installation/configuration and validation
- Cluster design - secure communication and high availability
- Installation - release binaries , kubeadm
- Network solution (network overlay)
- End to end testing of the cluster

Commands you need to know

go to getting started on k8s doc page.
setup