7. Services & Networking

Question 1

What is a service in Kubernetes ?

Answer 1

Enables communication between different components

Question 2

ServiceTypes

Answer 2

• NodePort
• ClusterIP
• LoadBalancer

Question 3

Define a service definition

service-definition.yaml

Answer 3

apiVersion: v1
kind: Service
metadata:
  name: myapp-service
spec:
  type: NodePort
  ports:
    - targetPort: 80
      port: 80
      nodePort: 30008
  selector:
    app: myapp
    type: front-end		

pod-definition.yaml

Question 4

Use one service in a Pod

pod-definition.yaml

Answer 4

apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels: 
    app: myapp
    type: front-end
spec:
  containers:
  - name: nginx-container
    image: nginx

Question 5

What is a ClusterIP

Answer 5

• The ClusterIP provides a load-balanced IP address.
• One or more pods that match a label selector can forward traffic to the IP address.
• The ClusterIP service must define one or more ports to listen on with target ports to forward TCP/UDP traffic to containers.

Question 6

What are the steps to define a service with ClusterIP

Answer 6

1. In the service definition should copy the tags from the pod-definion
   ~~~
   labels:
   app: myapp
   type: back-end
   ~~~
2. To service definition

  selector: 
    app: myapp
    type: back-end

Question 7

Define a service with ClusterIP

Answer 7

apiVersion: v1
kind: Service
metadata:
  name: back-end
spec:
  type: ClusterIP      < - Add the type
  ports:
    - targetPort: 80     < - Add the port
      port: 80
  selector: 
    app: myapp
    type: back-end

service-definition.yaml

Question 8

Diference between port and targetPort in a service

Answer 8

• In Kubernetes, when creating a service, you have to set the “port” and “targetPort” properties.
• A “port” refers to the container port exposed by a pod or deployment, while a “targetPort” refers to the port on the host machine that traffic is directed to.

Question 9

Implement a Pod with a service

Answer 9

apiVersion: v1 
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
    type: back-end
spec:
  containers:
  - name: nginx-container
    image: nginx

pod-definition.yaml

Question 10

What is Kubernetes Ingress

Answer 10

• Kubernetes Ingress is an API object that provides routing rules to manage external users’ access to the services in a Kubernetes cluster, typically via HTTPS/HTTP.
• With Ingress, you can easily set up rules for routing traffic without creating a bunch of Load Balancers or exposing each service on the node

Level 7 loadbalancer