kubernetes-deployment.md

Deployments

⬅️ Back to Kubernetes overview

Create a deployment with nginx

kubectl create deployment --image=nginx nginx 

So what is the difference? There is still a pod, but with a weird name

kubectl get pod
kubectl describe pod nginx-7769f8f85b-5wcxt # replace the pod name with yours!

Pod is "Controlled By" a ReplicaSet

kubectl get replicaset
kubectl describe replicaset nginx-7769f8f85b # replace the replicaset name with yours!

ReplicaSet is "Controlled By" the Deployment we've just created

kubectl get deployment
kubectl describe deployment nginx # this is the name we explicitly supplied during creation of the deployment

Labels are properties attached to each object. Selectors filter these items and can help you typing or even remembering the automatically generated resource names.

kubectl get pods --selector app=nginx
# the short version:
kubectl get pods -l app=nginx

Let's scale the deployment to more instances and watch what happens

kubectl get pods --watch --output wide
kubectl scale deployment nginx --replicas=2

See the new pods? What happens if we delete an existing pod?

kubectl delete pod -l "app=nginx"

To see some more results in the rollout handling afterwards, we are changing the image to an older version.

kubectl set image deployment nginx nginx=nginx:1.20.2

Check current pods

kubectl get pods

Delete the created resources

kubectl delete deployment nginx

Exercise

• Create a new deployment with the Apache Webserver (httpd) and two replicas.
• Change the version and apply the new deployment, monitor the pod, resource & deployment resources.
• Restore the previous version of the deployment