Two ways to give orders

There are two styles of working with Kubernetes, and the exam rewards knowing both.

Imperative: tell it what to do, one command at a time. Fast to type, perfect under exam pressure.

kubectl create deployment shop \
--image=shop:1.0 --replicas=3

Create a Deployment.

kubectl scale deployment shop --replicas=5

Change how many copies you want.

kubectl expose deployment shop \
--port=80 --target-port=8080

Create a Service for it, with the selector filled in for you.

kubectl run tmp --image=nginx

Create a single bare Pod (handy for quick tests).

kubectl run tmp --image=busybox:1.36 \
--rm -it --restart=Never -- \
wget -qO- http://shop

Test a Service from inside the cluster: a throwaway Pod fetches it, prints the answer, then disappears.

kubectl run job1 --image=busybox:1.36 \
--restart=Never -- echo hi

A one-shot Pod: restartPolicy: Never, so it runs once and stays Completed.

kubectl run web --image=nginx \
--dry-run=client -o yaml

Draft a Pod's YAML without creating anything.

kubectl port-forward svc/shop 8080:80

Reach the Service from your own machine at localhost:8080 (stop with Ctrl+C).

kubectl annotate pod shop-xk2pq \
note="canary"

Attach a note to something that exists. Unlike labels, annotations are not used to select objects.

kubectl label pod shop-xk2pq tier=web

Add a name tag to something that exists.

kubectl delete pod shop-xk2pq

Delete a Pod. Its Deployment replaces it.

Declarative: describe what you want in a YAML file and hand the whole file over. Repeatable, reviewable, and what teams use day to day.

kubectl apply -f shop.yaml

Create or update everything in the file to match it.

kubectl diff -f shop.yaml

Preview what apply would change.

kubectl delete -f shop.yaml

Remove everything the file describes.

The best of both: let kubectl write the YAML

Typing YAML from memory is slow and error-prone. Have kubectl draft it, then edit only what you need:

kubectl create deployment shop --image=shop:1.0 --replicas=3 \
  --dry-run=client -o yaml > shop.yaml

--dry-run=client means "don't create anything, just show me", and -o yaml prints it as YAML. This is the single most useful trick on the exam.

Handy flags for reading

-o wide

Extra columns, like IP and Node.

-o yaml

The full object, every field.

--show-labels

Show each object’s name tags.

-l app=shop

Only objects with this label.

-w

Keep watching for changes.

kubectl explain deployment.spec

Built-in docs for any field.

 Change a Deployment with kubectl edit deployment shop or by re-applying its file. Edit the Deployment, not its Pods: they are made from the Deployment's recipe, so a hand-made change is lost the next time a Pod is replaced.