Getting started

Instruction

Control plane vs worker nodes

Control Plane:

• The control plane is installed on your master node
• Can be both a control plane node and a worker node
• It houses the API server, scheduler, and controller manager settings

Worker Nodes:

• This is where the kubelet and kube-proxy are installed
• You can use the kubeadm join command to join workers to the master node to form the cluster

First Test

New Pod

shell-demo.yaml

apiVersion: v1
kind: Pod
metadata:
  name: shell-demo
spec:
  volumes:
  - name: shared-data
    emptyDir: {}
  containers:
  - name: nginx
    image: nginx
    volumeMounts:
    - name: shared-data
      mountPath: /usr/share/nginx/html
  hostNetwork: true
  dnsPolicy: Default

Create a Pod

kubectl apply -f https://k8s.io/examples/application/shell-demo.yaml

Verify that the container is running

kubectl get pod shell-demo

# Get a shell to the running container
kubectl exec -it shell-demo -- /bin/bash

New Deployment

nginx-deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Create a Deployment

kubectl apply -f https://k8s.io/examples/controllers/nginx-deployment.yaml

# Without a yaml file
kubectl apply -f - <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
EOF

Verify

kubectl get deployments
kubectl get pods --show-labels

Networking

Inbound Rules for K3s Nodes

Typically, all outbound traffic is allowed.

Network access to other pods

• Different Namespace: http://<service-name>.<namespace>:<port> 
• Same Namespace: http://<service-name>:<port> 

Network access within the same pod

• http://localhost:<port> 
• 每個 container 有不一樣的 port