PodsToNodes.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-ssd
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
nodeSelector:
disk: local_ssd
---
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-gpu
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
nodeSelector:
hardware: local_gpu
---
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
CreatePodsWithLabels.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-1
labels:
app: MyWebApp
deployment: v1
tier: prod
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
---
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-2
labels:
app: MyWebApp
deployment: v1.1
tier: prod
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
---
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-3
labels:
app: MyWebApp
deployment: v1.1
tier: qa
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
---
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-4
labels:
app: MyAdminApp
deployment: v1
tier: prod
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
---
Code language: CSS (css)deployment-label.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello-world
labels:
app: hello-world
spec:
replicas: 4
selector:
matchLabels:
app: hello-world
template:
metadata:
labels:
app: hello-world
spec:
containers:
- name: hello-world
image: gcr.io/google-samples/hello-app:1.0
ports:
- containerPort: 8080
service.yaml
apiVersion: v1
kind: Service
metadata:
name: hello-world
spec:
ports:
- port: 80
protocol: TCP
targetPort: 8080
selector:
app: hello-world
Commands
#Demo requires nodes c1-master1, c1-node1, c1-node2 and c1-node3
ssh aen@c1-master1
cd ~/content/course/m3/demos
#Create a collection of pods with labels assinged to each
more CreatePodsWithLabels.yaml
kubectl apply -f CreatePodsWithLabels.yaml
#Look at all the Pod labels in our cluster
kubectl get pods --show-labels
#Look at one Pod's labels in our cluster
kubectl describe pod nginx-pod-1 | head
#Query labels and selectors
kubectl get pods --selector tier=prod
kubectl get pods --selector tier=qa
kubectl get pods -l tier=prod
kubectl get pods -l tier=prod --show-labels
#Selector for multiple labels and adding on show-labels to see those labels in the output
kubectl get pods -l 'tier=prod,app=MyWebApp' --show-labels
kubectl get pods -l 'tier=prod,app!=MyWebApp' --show-labels
kubectl get pods -l 'tier in (prod,qa)'
kubectl get pods -l 'tier notin (prod,qa)'
#Output a particluar label in column format
kubectl get pods -L tier
kubectl get pods -L tier,app
#Edit an existing label
kubectl label pod nginx-pod-1 tier=non-prod --overwrite
kubectl get pod nginx-pod-1 --show-labels
#Adding a new label
kubectl label pod nginx-pod-1 another=Label
kubectl get pod nginx-pod-1 --show-labels
#Removing an existing label
kubectl label pod nginx-pod-1 another-
kubectl get pod nginx-pod-1 --show-labels
#Performing an operation on a collection of pods based on a label query
kubectl label pod --all tier=non-prod --overwrite
kubectl get pod --show-labels
#Delete all pods matching our non-prod label
kubectl delete pod -l tier=non-prod
#And we're left with nothing.
kubectl get pods --show-labels
#Kubernetes Resource Management
#Start a Deployment with 3 replicas, open deployment-label.yaml
kubectl apply -f deployment-label.yaml
#Expose our Deployment as Service, open service.yaml
kubectl apply -f service.yaml
#Look at the Labels and Selectors on each resource, the Deployment, ReplicaSet and Pod
#The deployment has a selector for app=hello-world
kubectl describe deployment hello-world
#The ReplicaSet has labels and selectors for app and the current pod-template-hash
#Look at the Pod Template and the labels on the Pods created
kubectl describe replicaset hello-world
#The Pods have labels for app=hello-world and for the pod-temlpate-hash of the current ReplicaSet
kubectl get pods --show-labels
#Edit the label on one of the Pods in the ReplicaSet, change the pod-template-hash
kubectl label pod hello-world-5646fcc96b-kjvnl pod-template-hash=DEBUG --overwrite
#The ReplicaSet will deploy a new Pod to satisfy the number of replicas. Our relabeled Pod still exists.
kubectl get pods --show-labels
#Let's look at how Services use labels and selectors, check out services.yaml
kubectl get service
#The selector for this serivce is app=hello-world, that pod is still being load balanced to!
kubectl describe service hello-world
#Get a list of all IPs in the service, there's 5...why?
kubectl describe endpoints hello-world
#Get a list of pods and their IPs
kubectl get pod -o wide
#To remove a pod from load balancing, change the label used by the service's selector.
#The ReplicaSet will respond by placing another pod in the ReplicaSet
kubectl get pods --show-labels
kubectl label pod hello-world-5646fcc96b-kjvnl app=DEBUG --overwrite
#Check out all the labels in our pods
kubectl get pods --show-labels
#Look at the registered endpoint addresses. Now there's 4
kubectl describe endpoints hello-world
#To clean up, delete the deployment, service and the Pod removed from the replicaset
kubectl delete deployment hello-world
kubectl delete service hello-world
kubectl delete pod hello-world-5646fcc96b-kjvnl
#Scheduling a pod to a node
#Scheduling is a much deeper topic, we're focusing on how labels can be used to influence it here.
kubectl get nodes --show-labels
#Label our nodes with something descriptive
kubectl label node c1-node2 disk=local_ssd
kubectl label node c1-node3 hardware=local_gpu
#Query our labels to confirm.
kubectl get node -L disk,hardware
#Create three Pods, two using nodeSelector, one without.
more PodsToNodes.yaml
kubectl apply -f PodsToNodes.yaml
#View the scheduling of the pods in the cluster.
kubectl get node -L disk,hardware
kubectl get pods -o wide
#Clean up when we're finished, delete our labels and Pods
kubectl label node c1-node2 disk-
kubectl label node c1-node3 hardware-
kubectl delete pod nginx-pod
kubectl delete pod nginx-pod-gpu
kubectl delete pod nginx-pod-ssd
Code language: PHP (php)Sorry, there was a YouTube error.
I’m a DevOps/SRE/DevSecOps/Cloud Expert passionate about sharing knowledge and experiences. I have worked at Cotocus. I share tech blog at DevOps School, travel stories at Holiday Landmark, stock market tips at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow , and SEO strategies at Wizbrand.
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