Challenge - Service

Write a NodePort Service and connect to Pods.

Challenge: internal and external services

An application has two faces: internal services (API, database) are reached only from inside the cluster, while the front end is reached from outside. In this challenge you'll write the right Services for both and verify that they work.

api (ClusterIP)  : http://api:8000          # cluster-internal only
web (NodePort)   : http://<node-ip>:30080   # from outside

kubectl run -it --rm t --image=busybox:1.36 --restart=Never -- wget -qO- http://api:8000/saglik

Exercise The API service

Write a Service YAML: name api, type: ClusterIP; selector app: api; port port: 8000, targetPort: 8000.

Show example solution

apiVersion: v1
kind: Service
metadata:
  name: api
spec:
  type: ClusterIP
  selector:
    app: api
  ports:
    - port: 8000
      targetPort: 8000

Exercise The web service and verification

Write two commands: expose the web deployment with --type=NodePort --port=80 --target-port=8080; in an interactive pod t with busybox:1.36 that is deleted on exit and doesn't restart, run wget -qO- http://api:8000/saglik.

Show example solution

kubectl expose deployment web --type=NodePort --port=80 --target-port=8080
kubectl run -it --rm t --image=busybox:1.36 --restart=Never -- wget -qO- http://api:8000/saglik

Test yourself

Is it possible to write port: 8000 and targetPort: http in the API service?
- Only with NodePort
- Only for HTTPS
- Yes; if the container port was named with name: http
- No, targetPort must be a number
Show answer

Yes; if the container port was named with name: http — A named port keeps working even if the container port changes, without changing the service.
Expose the service only inside the cluster.
```
spec:
  type: ____
```
Show answer
```
spec:
  type: ClusterIP
```
Match.

api ClusterIP

Internal access
web NodePort

External access
targetPort: http

Named port
wget http://api:8000

Internal verification

Next lesson: Challenge - ConfigMap

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