Hello all, This is definitely something super silly I am doing, but I cannot fig . . .

Kubernetes-Slack Discussions
#1

Sudi Krishnakumar:
hello all, This is definitely something super silly I am doing, but I cannot figure out what I am doing wrong for the life of me

so I have the following aliases set up
alias k=kubectl
alias doyaml=" --dry-run=client -oyaml"

now I do
k run nginx-pod --image=nginx:alpine doyaml > nginx-pod.yaml

and when I open the nginx-pod.yaml I see the result in it which is pod/nginx-pod created

However when I do
k run nginx-pod --image=nginx:alpine --dry-run=client -oyaml > nginx-pod.yaml

The correct yaml pod spec is created.

I do not understand why the alias doyaml does not seem to work in the first case? Appreciate if anyone can enlighten me! Thanks

#2

Alistair Mackay:
@Sudi Krishnakumar you need to do it a a shell variable

#3

Alistair Mackay:

export doyaml='--dry-run=client -o yaml'

k run nginx-pod --image=nginx:alpine $doyaml > nginx-pod.yaml

Note the $ to expand the shell variable

#4

Alistair Mackay:
Save yourself extra typing by simply calling it y instead of doyaml

#5

Sudi Krishnakumar:
Thanks mate!

#6

Pallavi Sharma:
Does this mean we need to always use export instead of Alias directly?

#7

Pallavi Sharma:
@Alistair Mackay

#8

Alistair Mackay:
export and alias are different things.

• alias creates an alias for a runnable command (optionally with some of its arguments)
• export creates a shell variable which is visible to any program or subshell you run from the terminal.
--dry-run-client -o yaml is not a command in its own right, therefore we use a shell variable for it which can be expanded in the context of a longer command line. So

alias k=kubectl
export y='--dry-run=client -o yaml`

k run nginx-pod --image=nginx:alpine $y > nginx-pod.yaml

k is an alias. Note that it is pre-existing in the exam so you don’t have to create it.
y is a shell variable. Note the use of quotes above. This is necessary since the value includes spaces.

The shell therefore interprets the above as

kubectl run nginx-pod --image=nginx:alpine --dry-run=client -o yaml > nginx-pod.yaml

This is basic Linux stuff. Anyone doing Kubernetes is recommended to also do a basic Linux course, like https://kodekloud.com/courses/the-linux-basics-course/

#9

Alistair Mackay:
A good alias to create is this

alias kgp='kubectl get pods'

Then you can do

kgp

or

kgp -o wide

etc

also

alias kcn='kubectl config set-context --curreent --namespace'

so

kcn my-namespace

Time savers in exam!

#10

Alistair Mackay:
https://github.com/fireflycons/tips-for-CKA-CKAD-CKS#creating-and-using-your-own-aliases-and-exports