oc-deployment.md

Deployments

⬅️ Back to Kubernetes overview

Create a deployment with httpd

oc create deployment --image=ubi8/httpd-24 httpd 

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

oc get pod
oc describe pod httpd-7769f8f85b-5wcxt # replace the pod name with yours!

Pod is "Controlled By" a ReplicaSet

oc get replicaset
oc describe replicaset httpd-7769f8f85b # replace the replicaset name with yours!

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

oc get deployment
oc describe deployment httpd # 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.

oc get pods --selector app=httpd
# the short version:
oc get pods -l app=httpd

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

oc get pods --watch --output wide
oc scale deployment httpd --replicas=2

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

oc delete pod -l "app=httpd"

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

oc set image deployment httpd httpd-24=ubi8/httpd-24:1-340

Check current pods

oc get pods

Delete the created resources

oc delete deployment httpd

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