Working with Services in Kubernetes

Task 1:Create a Service for accessing todo-app

1. Create a Service for your todo-app Deployment from Day-32

   Create a Service definition for your todo-app Deployment in a YAML file.

   Now create a service.yml where we will deploy NodePort.

     apiVersion: v1
     kind: Service
     metadata:
       name: my-django-app-service
       namespace: my-django-app
     spec:
       type: NodePort
       selector:
         app: django-app
       ports:
           # By default and for convenience, the 'targetPort' is set to the same value as the 'port' field.
         - port: 80
           targetPort: 8000
           # Optional field
           # By default and for convenience, the Kubernetes control plane will allocate a port from a range (default: 30000-32767)
           nodePort: 30009
   

   Apply the Service definition to your K8 cluster using the kubectl apply -f service.yml.

     kubectl apply -f service.yml
   
     # Getting the service. (svc is short form of service)
     kubectl get svc -n=my-django-app
   

   So edit the inbound rule of the worker node and add port number 30009 so that we can access the pod outside

   Verify that the Service is working by accessing the todo-app using the Service's IP and Port in your Namespace.

   

Task 2:Create a ClusterIP Service for accessing the todo-app

Create a ClusterIP Service for accessing the todo-app from within the cluster

 vi cluster-ip-service.yml

 apiVersion: v1
 kind: Service
 metadata:
   name: my-django-app-cluster
   namespace: my-django-app
 spec:
   type: ClusterIP
   selector:
     app: django-app
   ports:
     - name: http
       protocol: TCP
       port: 8000
       targetPort: 8000

Apply the Service definition to the cluster using the following command:

 kubectl apply -f cluster-ip-service.yml -n my-django-app

Verify that the service is running by running the following command:

 kubectl get svc -n my-django-app

Deploy another Pod in the my-django-app namespace to test the service. You can use the following YAML definition to create a simple test Pod:

 apiVersion: v1
 kind: Pod
 metadata:
   name: test-pod
   namespace: my-django-app
 spec:
   containers:
   - name: busybox
     image: busybox
     command: ['sh', '-c', 'while true; do wget -q -O- my-django-app-cluster-ip:8000; done']

Apply the Pod definition using the following command:

 kubectl apply -f test-pod.yml -n my-django-app

Now enter into this pod :

 kubectl exec -it test-pod -n my-django-app -- /bin/sh

Open the port for the new pod in the inbound rule

Test Todo app

 # Inside the test pod execute the wget commad.
 wget -qO- http://<ip-of-my-django-app-cluster-ip>:<port

 # wget -qO- http://10.111.195.250:8000

Now you successfully Access it through another Port:

Task 3:Create a LoadBalancer Service for accessing the todo-app

Create a YAML file named load-balancer-service.yml with the following contents:

 apiVersion: v1
 kind: Service
 metadata:
   name: my-django-app-cluster-ip
   namespace: my-django-app
 spec:
   selector:
     app: django-app
   ports:
     - port: 80
       targetPort: 8000
   type: LoadBalancer

Apply the LoadBalancer Service definition to your K8s cluster using the following command:

 kubectl apply -f load-balancer-service.yml -n my-django-app

Verify that the LoadBalancer Service is working by accessing the todo-app from outside the cluster in your namespace.

 kubectl get service -n=my-django-app

Get the IP from the service and then open the port in the Worker Node.

copy the Public IPv4 DNS and access through the browser by providing the port number in the URL.

 Public-IPv4-DNS:<loadbalancer-port-number>

For another Kubernetes project.

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