luc.run

Exercise

In this exercise, you will create a Deployment and expose it outside the cluster via a NodePort service.

Create a ghost_deployment.yaml file defining a Deployment with the following properties:

name: ghost
number of replicas: 3
selector definition for the label app: ghost
Pod specification:
- label app: ghost
- a container named ghost based on the ghost:4 image and exposing port 2368

Then create the specified resource.

Examine the status of the ghost Deployment.

Based on this information, what can you say about the number of Pods managed by this Deployment?

List the Pods associated with this Deployment.
Create a Service to expose the Deployment’s Pods outside the cluster

Tips:

you can start by creating a Service specification, specifying that the selector should group Pods with the label app: ghost
use a NodePort type service, you can publish it on port 31001 of the cluster nodes
the container based on the ghost:4 image runs on port 2368, this port should therefore be referenced as targetPort in the Service specification

Note: feel free to refer to the NodePort Services exercise we saw previously

Once the service is created, you will be able to access the ghost application interface on http://IP:31001 where IP is the IP address of a machine in the Kubernetes cluster.

Note: you can get the IPs of your cluster machines with the command $ kubectl get nodes -o wide

Ghost application interface

Delete the Deployment and Service created previously.

Solution

The specification, defined in the ghost_deployment.yaml file is as follows:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ghost
spec:
  replicas: 3
  selector:
    matchLabels:
      app: ghost
  template:
    metadata:
      labels:
        app: ghost
    spec:
      containers:
      - name: ghost
        image: ghost:4
        ports:
        - containerPort: 2368

The following command creates the Deployment:

kubectl apply -f ghost_deployment.yaml

The following command shows the Deployment status:

$ kubectl get deploy
NAME   READY   UP-TO-DATE   AVAILABLE   AGE
ghost   3/3     3            3          51s

The following command lists the Pods running on the cluster:

$ kubectl get po
NAME                    READY   STATUS    RESTARTS   AGE
ghost-548879c755-7kmpz   1/1     Running   0          68s
ghost-548879c755-m5pjt   1/1     Running   0          68s
ghost-548879c755-nwl9l   1/1     Running   0          68s

We can see that the 3 Pods related to the ghost Deployment are listed. They are all active.

In a ghost_service.yaml file we define the following specification:

apiVersion: v1
kind: Service
metadata:
  name: ghost
spec:
  selector:
    app: ghost
  type: NodePort
  ports:
  - port: 80
    targetPort: 2368
    nodePort: 31001

Then create the Service:

kubectl apply -f ghost_service.yaml

Delete the Deployment and Service:

kubectl delete deploy/ghost
kubectl delete svc/ghost