kubectl-basic-admin.md

Working with kubectl for basic administrations

Let's run your first Nginx deployment with kubectl

$ kubectl run nginx --image=nginx --port 80
deployment.apps "nginx" created

Under the hood, this will create one deployment with one replicaset with one single nginx pod for you. (please ignore service/kubernetes)

$ kubectl get all
NAME                         READY     STATUS    RESTARTS   AGE
pod/nginx-768979984b-jr8wv   1/1       Running   0          44s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.100.0.1   <none>        443/TCP   2h

NAME                    DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx   1         1         1            1           44s

NAME                               DESIRED   CURRENT   READY     AGE
replicaset.apps/nginx-768979984b   1         1         1         44s

Create a port-forward and mapping the port from Pod TCP:80 to Cloud9 localhost:8080

$ kubectl port-forward deployment/nginx 8080:80
Forwarding from 127.0.0.1:8080 -> 80
Forwarding from [::1]:8080 -> 80

And preview it from Cloud9

get current deploy, replicaset and pods

$ kubectl get deploy,rs,po

scale the replicaset from 1 to 4

$ kubectl scale deploy/nginx --replicas=4

And check it again

$ kubectl get deploy,rs,po

Now, expose the deployment as a Service with Type=LoadBalancer.

$ kubectl expose deploy/nginx --port 80 --target-port 80 --type LoadBalancer

Paste the ELB endpoint URL in the browser. You will see the Nginx welcome page.

Let's scale back to 1 Pod and watch the access logs

(keep reloading the browser with the ELB URL and see the log flowing)

Now, update the nginx docker image to openresty:alpine

$ kubectl set image deploy/nginx nginx=openresty/openresty:alpine
deployment.apps "nginx" image updated

reload and see the OpenResty welcome page

Edit the deployment and update the image to abiosoft/caddy:php and containerPort to 2015

$ kubectl edit deploy/nginx

Edit the service as well. Specify the targetPort to 2015

$ kubectl edit svc/nginx

Reload the browser, now you get Caddy web server with PHP support.

Clean up

Delete the nginx service and deployment.

$ kubectl delete svc/nginx deploy/nginx
service "nginx" deleted
deployment.extensions "nginx" deleted

(this will terminate the nginx service, delete the ELB, delete the replicaset and all the nginx pods)