I'm running the example in chapter "Service Discovery" of the book "Kubernetes up and running". The original command to run a deployment is kubectl run alpaca-prod --image=gcr.io/kuar-demo/kuard-amd64:blue --replicas=3 --port=8080 --labels="ver=1,app=alpaca,env=prod", however in K8s version 1.25, the --replicate parameter in run command is not supported any more. I planned to run without replica and then use "kubectl scale" to scale the deployment later. Problem is the run command only creates a pod, not a deployment (the scale command expects a deployment). So how do i promote my pod to a deployment, my kubernetes verion is 1.25?
There is no way to promote it however you can change label and all those stuff but instead of that you can create the new deployment delete the existing POD.
So easy step you can take input of existing running POD to YAML file first
kubectl get pod <POD name> -o yaml > pod-spec.yaml
Create deployment spec YAML file now
kubectl create deployment deploymentname --image=imagename --dry-run=client -o yaml > deployment-spec.yaml
Edit the deployment-spec.yaml file
and in other tab pod-spec.yaml you can copy the Spec part from POD file to new deployment file.
Once deployment-spec.yaml is ready you can apply it. Make sure if you are running service labels get matched properly
kubectl apply -f deployment-spec.yaml
Delete the single running POD
kubectl delete pod <POD name>
Related
I was setting up a nginx cluster on google cloud, and I entered a wrong image name; instead of entering:
kubectl create deploy nginx --image=nginx:1.17.10
I entered:
kubectl create deploy nginx --image=1.17.10
and eventually after running kubectl get pods, It showed ImagePullBackOff as the status for the pod.
When I tried running the correct create deploy command above, It said "nginx" already exists.
When I tried doing kubernetes delete --all pods, the pod was recreated with a new ID but still had the same status, and still couldn't allow me to run the right 'kubectl create deploy' command above. Now I'm stuck.
How can I undo it?
You need to delete the deployment:
kubectl delete deploy nginx
Otherwise Kubernetes will recreate the pod on every shutdown.
You can see all your deployments with
kubectl get deploy
Edit the deployment via kubectl edit deployment DEPLOYMENT_NAME and change the image name.
Or
Edit the manifest file and append the file with a correct image mane and do a kubectl apply -f YAML file
First of all, your k8s cluster is trying to pull image 1.17.10 from public docker registry. But as there are no image exists with this name that's why it's get error. And when you have tried to delete your pods it will again try to create with same image name as your deployment is exists. For this reason you need to delete deployment rather then pods. Otherwise, deployment will automatically try to create deleted pod again.
you can actually check what was the error in your deployment with this command:
kubectl describe deploy nginx
For you the command will bekubectl delete deploy -n <Namespace_name> <deployment_name>. As you have created your deployment in default namespace you don't need to mention the namespace automatically it will be the default namespace.
you can delete deployment with this command:
kubectl delete deploy nginx
I usually restart my applications by:
kubectl scale deployment my-app --replicas=0
Followed by:
kubectl scale deployment my-app --replicas=1
which works fine. I also have another running application but when I look at its replicaset I see:
$ kubectl get rs
NAME DESIRED CURRENT READY AGE
another-app 2 2 2 2d
So to restart that correctly I would of course need to:
kubectl scale deployment another-app --replicas=0
kubectl scale deployment another-app --replicas=2
But is there a better way to do this so I don't have to manually look at the repliasets before scaling/restarting my application (that might have replicas > 1)?
You can restart pods by using level
kubectl delete pods -l name=myLabel
You can rolling restart of all pods for a deployments, so that you don't take the service down
kubectl patch deployment your_deployment_name -p \
"{\"spec\":{\"template\":{\"metadata\":{\"annotations\":{\"date\":\"`date +'%s'`\"}}}}}"
And After kubernetes version 1.15 you can
kubectl rollout restart deployment your_deployment_name
To make changes in your current deployment you can use kubectl rollout pause deployment/YOUR_DEPLOYMENT. This way the deployment will be marked as paused and won't be reconciled by the controller. After it's paused you can make necessary changes to your configuration and then resume it by using kubectl rollout resume deployment/YOUR_DEPLOYMENT. This way it will create a new replicaset with updated configuration.
Pod with new configuration will be started and when it's in running status, pod with old configuration will be terminated.
Using this method you will be able to rollout the deployment to previous version by using:
kubectl rollout history deployment/YOUR_DEPLOYMENT
to check history of the rollouts and then execute following command to rollback:
kubectl rollout undo deployment/YOUR_DEPLOYMENT --to-revision=REVISION_NO
Using kubectl command line, is it possible to define the exact pod name?
I have tried with
kubectl run $pod-name --image imageX
However, the resulted pod name is something like $pod-name-xx-yyy-nnn.
So without using a yaml file, can I define the pod name using kubectl CLI?
kubectl run creates a Deployment by default. A Deployment starts a ReplicaSet that manages the pods/replicas... and therefore has a generated pod name.
Run pod
To run a single pod you can add --restart=Never to the kubectl run command.
kubectl run mypod --restart=Never --image=imageX
The $pod-name is a variable with some value let's say "hello". So when you are running the kubectl run command it will create a deployment. The deployment will create a replicaset with name "hello-xxxx" and the replicaset will create pod with name "replicasetname-xxx".
If you want to create a pod using kubectl run use the below command "kubectl run times --generator=run-pod/v1 hello --image=busybox".
It will create a pod with name hello. You are suppose to replace hello and image name.
Otherwise you could use "kubectl create pod hello --image=busybox".
I create a pod by configuration file with a volume and privileged security.
How can I deploy this pod?
I try to deploy with kubectl run or deployment configuration file. it's created a new pod without my volume and security privileged.
Best regards,
Daniel
Use these commands to create and verify
This will create the pod
# kubectl create -f abc-pod.yml
This will list the running pods
# kubectl get pods
This will show the details of that pod
# kubectl describe pod <pod_name>
This will show the logs of pods
# kubectl logs pod_name container_name
I am starting exploring runnign docker containers with Kubernetes. I did the following
Docker run etcd
docker run master
docker run service proxy
kubectl run web --image=nginx
To cleanup the state, I first stopped all the containers and cleared the downloaded images. However I still see pods running.
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
web-3476088249-w66jr 1/1 Running 0 16m
How can I remove this?
To delete the pod:
kubectl delete pods web-3476088249-w66jr
If this pod is started via some replicaSet or deployment or anything that is creating replicas then find that and delete that first.
kubectl get all
This will list all the resources that have been created in your k8s cluster. To get information with respect to resources created in your namespace kubectl get all --namespace=<your_namespace>
To get info about the resource that is controlling this pod, you can do
kubectl describe web-3476088249-w66jr
There will be a field "Controlled By", or some owner field using which you can identify which resource created it.
When you do kubectl run ..., that's a deployment you create, not a pod directly. You can check this with kubectl get deploy. If you want to delete the pod, you need to delete the deployment with kubectl delete deploy DEPLOYMENT.
I would recommend you to create a namespace for testing when doing this kind of things. You just do kubectl create ns test, then you do all your tests in this namespace (by adding -n test). Once you have finished, you just do kubectl delete ns test, and you are done.
If you defined your object as Pod then
kubectl delete pod <--all | pod name>
will remove all of the generated Pod. But, If wrapped your Pod to Deployment object then running the command above only will trigger a re-creation of them.
In that case, you need to run
kubectl delete deployment <--all | deployment name>
That will also remove the Service object that is related to the deleted Deployment