Introduction to kubectl

Deployment of the needed description in kubernetes

These are two approaches to create the description in Kuberentes:

# create a namespace 
kubectl create namespace web-test

# Then choose one way:
# (1) Create the description
kubectl create -f nginx.yml -f service.yml

# (2) Create or update descriptions if existing
kubectl apply -f nginx.yml -f service.yml

To show it is working

Here are some useful commands:

# show nodes
kubectl get nodes

# show pods for our namespace
kubectl get -n web-test pods 

# show deployments for our namespace
kubectl get -n web-test deployment

# show services for our namespace
kubectl show -n web-test service

# show logs of deployed nginx instances
kubectl logs -n web-test deployment/nginx-deployment

Scaling up and down

# scale up instances to 5
kubectl scale deployment/nginx-deployment --replicas=5

# scale down instances again to 3
kubectl scale deployment/nginx-deployment --replicas=3

To see it is working in the browser ;)

The nginx instances are reachable at the floating ips of the node-instances at port 30007 in our case.

Many other things can be done ;)

Autoscaling
Detailled Service functions (LoadBalancer, ...)
Dashboard
FaaS Setup ;)
...

Appendix

Nginx description

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: web-test
spec:
  selector:
    matchLabels:
      app: nginx-deployment
  replicas: 3 # tells deployment to run 3 pods matching the template
  template:
    metadata:
      labels:
        app: nginx-deployment
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

Nginx service description

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: web-test
spec:
  type: NodePort
  selector:
    app: nginx-deployment
  ports:
      # By default and for convenience, the `targetPort` is set to the same value as the `port` field.
    - port: 80
      targetPort: 80
      # Optional field
      # By default and for convenience, the Kubernetes control plane will allocate a port from a range (default: 30000-32767)
      nodePort: 3000

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