Kubernetes JRC Training

• doc: https://kubernetes.io/docs/reference/kubernetes-api/

echo -e '\nsource <(kubectl completion bash)\n' >> ~/.bashrc

master node

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

for each node:

sudo kubeadm join 172.31.4.94:6443 --token s99adr.q3wjstujf1rjceun
--discovery-token-ca-cert-hash sha256:8bb4eb3c372738e3fbcf498f9edbbd772571b87f7e829a97455e813106cb1b45

Admin commands

kubectl get all -A

kubectl get node kubectl get namespace # or kubectl get ns kubectl get pod -n kube-system

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml kubectl get pod -n kube-system kubectl get node

kubectl describe nodes ip-master kubectl describe nodes ip-node1 kubectl describe nodes ip-node2

kubectl get pod -n kube-system -o wide kubectl logs -n kube-system <pod>

Role-Based AC

kubectl get roles.rbac.authorization.k8s.io -A

kubectl get clusterrole -A kubectl describe clusterrole admin

kubectl get serviceaccount kubectl describe serviceaccounts default kubectl create serviceaccount -o yaml --dry-run

Deploy a pod

Produce an yaml:

kubectl run myfirstpod --image=nginx:1.19 --dry-run -o yaml > myfirst.yaml

Trim yaml:

~/myfirstpod

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: myfirstpod
  name: myfirstpod
spec:
  containers:
  - image: nginx:1.19
    name: myfirstpod

kubectl apply -f myfirstpod.yaml

kubectl run myfirstpod --image=nginx:1.19

kubectl describe pod myfirstpod kubectl describe pod # all pods in default ns

kubectl get pod myfirstpod -o yaml

kubectl delete pod myfirstpod

kubectl exec -it myfirstpod -- bash

Hide a cluster IP behind a Service

sample: lab/01b-two-container.yaml ...

kubectl create service clusterip <name> <port>:<targetPort> --dry-runner then edit & apply

kubectl get endpoints

apiVersion: v1
kind: Service
metadata:  name: svc-frontend
spec:  ports:  - name: 80-80
    port: 80
    protocol: TCP
    targetPort: 80
selector:
    app: svc-frontend
type: ClusterIP

Deployements

file: 11a-ngnix-...

kubectl rollout status deployment nginx
kubectl rollout history deployment nginx
kubectl rollout history deployment --revision=3
kubectl rollout undo deployment nginx --to-revision 1

Services

file: 11b-ngnix-...

kubectl apply -f 11b-nginx-deploy-service.yaml
kubectl get pod --show-labels
kubectl get service
kubectl describe service servicenginx

Docker Registry

• harbor.io FOSS installable registry

Quotas per ns

file: 10-quota.yaml prometheus.io

Git org

helm.sh

DBs & Stateful apps

• k8s statefulset (not deployment)

Questions

• Q: confusing to deal with names (internal/external IPs, DNS) - how to assign own names?
  • Q: how not to hard-code IPs? SERVICES? LABELs
• Q: how to organize applicable files in Git? HELM
• Q: is there a modus operandi for starting small and augmenting files while migrating pods-->deployments & hooking services?
• Q: gateways/ingress
• Q: clean up/gc leave behind resources? YES, linstall distribution
• Q: Change certificate to include another IP?  Martino Fornasa
• Q: Network config? https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml