3. Services.md

Services

Labels and annotations

Create 3 pods with names nginx1,nginx2,nginx3. All of them should have the label app=v1

kubectl run nginx1 --image=nginx --restart=Never --labels=app=v1
kubectl run nginx2 --image=nginx --restart=Never --labels=app=v1
kubectl run nginx3 --image=nginx --restart=Never --labels=app=v1

#Example above uses command line to generate pods with labels, try defining them using YAML all in one file 

Show all labels of the pods

kubectl get po --show-labels

Change the labels of pod 'nginx2' to be app=v2

kubectl label po nginx2 app=v2 --overwrite

Get the label 'app' for the pods

kubectl get po -L app

Get only the 'app=v2' pods

kubectl get po -l app=v2
# or
kubectl get po -l 'app in (v2)'

Remove the 'app' label from the pods we created before

kubectl label po nginx1 nginx2 nginx3 app-
# or
kubectl label po -l app app-
# or if on linux
kubectl label po nginx{1..3} app-

Annotate pods nginx1, nginx2, ngingx3 with "description='my description'" value

kubectl annotate po nginx1 nginx2 nginx3 description="my description"

Check the annotations for pod nginx1

kubectl describe po nginx1 
# or if on linux, take advantage of grep
kubectl describe po nginx1 | grep -i "annotations"

Remove the annotations for these three pods

kubectl annotate po nginx1 nginx2 nginx3 description-
# or if on linux
kubectl annotate po nginx{1..3} description-

Remove these pods to have a clean state in your cluster

kubectl delete po nginx1 nginx2 nginx3
# or if on linux
kubectl delete po nginx{1..3}

Services

Create a pod with image nginx called nginx and expose its port 80

kubectl run nginx --image=nginx --restart=Never --port=80 --expose
# observe that a pod as well as a service are created

Confirm that ClusterIP has been created. Also check endpoints

kubectl get svc nginx # services
kubectl get ep # endpoints

Get pod's ClusterIP, create a temp busybox pod and 'hit' that IP with wget

kubectl get svc nginx # get the IP (something like 10.108.93.130)
kubectl run busybox --rm --image=busybox -it --restart=Never -- sh
wget -O- IP:80
exit

Convert the ClusterIP to NodePort and find the NodePort port.

kubectl edit svc nginx
kubectl get svc 

Convert the NodePort to LoadBalancer and find the Public IP

kubectl edit svc nginx
kubectl get svc -w

Access the Service in your browser

• Browser > IP

Delete all resources in the current namespace

kubectl delete all --all