Challenge - Service
- Docker & Kubernetes course
- Intermediate
- Lesson 80/82
- 5 min
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/saglikPractice The API service
Write a Service YAML: name api, type: ClusterIP; selector app: api; port port: 8000, targetPort: 8000.
Starter code
# buraya yazSample solution
apiVersion: v1
kind: Service
metadata:
name: api
spec:
type: ClusterIP
selector:
app: api
ports:
- port: 8000
targetPort: 8000Expected output
service/api created
Practice 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.
Starter code
# buraya yazSample 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/saglikExpected output
service/web exposed
{"durum":"ok"}
pod "t" deleted
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 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 Correct answer
- No, targetPort must be a number
Explanation: A named port keeps working even if the container port changes, without changing the service.
2 Expose the service only inside the cluster.
spec:
type: ____spec:
type: ClusterIPExplanation: ClusterIP is the default, internal type.
3 Match.
| Term | Meaning |
|---|---|
api ClusterIP |
Internal access |
web NodePort |
External access |
targetPort: http |
Named port |
wget http://api:8000 |
Internal verification |