Rich

Azure DevOps, Terraform, PowerShell, Azure Policy and more.

Linux - How to Deploy Containers to a Kubernetes Cluster

Prerequisites

• Setup a K8s Cluster

Steps - Performed on the Controller

Create K8s Deployment YAML for a Pod and Service

• Create a directory to store the deployment files mkdir k8s_services
• Create a YAML file that describes the Pod and Container specification sudo pod.yml:

apiVersion: v1
kind: Pod
metadata:
  name: nginx-example
  labels:
    app: nginx
spec:
  containers:
    - name: nginx
      image: linuxserver/nginx
      ports:
        - containerPort: 80
          name: "nginx-http"

Note: labels are key values pairs for reference. linuxserver/nginx is the https://linuxserver.io image repository that support both x86 and ARM architectures (Pis). containerPort is the port the container exposes to the internal K8s network only at this stage.

• Create a YAML file that describes the NodePort service to provide the ability to map a network port on a Pod to the Node it is running on sudo service-nodeport.yml:

apiVersion: v1
kind: Service
metadata:
  name: nginx-example
spec:
  type: NodePort
  ports:
    - name: http
      port: 80
      nodePort: 30080
      targetPort: nginx-http
  selector:
    app: nginx

Note: nodePort may be between 30000 - 32767. The selector value is a way to reference pods that the configuration applies to using the pod’s label.

Apply the Deployment YAML to the K8s Cluster

• Apply the Pod and Container specification: kubectl apply -f pod.yml
  • Check the pod status kubectl get pods, you can see additional fields with kubectl get pods -o wide.
• Apply the NodePort service specification: kubectl apply -f service-nodeport.yml
  • Check the status of the service kubectl get services
  • Test connectivity using:

    curl http://192.168.101.90:30080
    curl http://192.168.101.91:30080
    curl http://192.168.101.92:30080
    

    Note: If you browse to any node ip address in the cluster on the given port the requests are directed to the Node that the Pod is running on.

Remove the Pod and Service K8s Cluster

• Remove the Pod and Container specification:

  kubectl delete pod nginx-example
  kubectl get pods
  

• Remove the NodePort service specification:

  kubectl delete service nginx-example
  kubectl get services