study-lfs258-11-09-2026

Today I’m continueing to go through the journey of writing again. This time I will write my experience off learning for my CKA exam.

What I learned this morning:

• Getting formiliar with the –dry-run flag

  • Essentially this just give you the output without all the unique information printed it out to stdout.
  • Somethink like this would look like:
  kubectl create deployment two --image=nginx --dry-run=client -o yaml

  • It is in fact a simulation of the command without doing anything

• Similar to just printing out a yaml file with the cat command you can also get its information with the -o yaml option:

kubectl get deployments nginx -o yaml

• The biggest difference is with the way of looking it like this is that you can see the ’live’ data.

  • It includes status and metadata.
  • You can see it more like its latest ‘snapshot’

• The same you can do for JSON as well:

kubectl get deployment nginx -o json

• To be able to see the effect of the nginx container a service is needed to be able to see the ‘default web page ( nginx )’. With the following command you can create a service out of the deployment that is already there.

kubectl expose deployment/nginx

• Also with the kubectl expose -h you can look up some more information about the command and see some different examples of using this.
• Now this command will give you an error due to there is no declared port.

mjerta@pi-control-1:~ $ kubectl expose deployment nginx
error: couldn't find port via --port flag or introspection

• What you could do is what the expose -h was already suggesting and just put the port in the same command but the course is trying to teach me another way.

• You can in fact change an object with the apply, edit or patch sub-commands. Not these are for non-disruptive updates.

• If you need be given a disruptive update this could be done with replace --force subcommand.

• By following the course I just did the edit manually by first adding the ports lines inside the correct container - vim into first.yaml

containers:
	- image: nginx
	imagePullPolicy: Always
	name: nginx
	ports:
	- containerPort: 80
	  protocol: TCP
	resources: {}

• And then perform the update with:

kubectl replace -f first.yaml --force

• The result will look like this:

mjerta@pi-control-1:~ $ kubectl replace -f first.yaml force
deployment.apps/nginx replaced

• Running the following you will that the creating of the deployment and the recreation of the pod is different now:

mjerta@pi-control-1:~ $ kubectl get deploy,pod
NAME                    READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx   1/1     1            1           2d23h

NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-75fdcbbc74-5bbl5   1/1     Running   0          5m35s

I notice I’m also repeating my own notes a bit much now. So I will try to give you in the an more general overview at the end. If I’m not done with this journal yet.