CODEWITHSUNDEEP
kubernetes
user8902801
user8902801

Reputation:

How to map nodePort to my own defined port

I have a service which is accessible on 8081. If I do via docker-compose or swarm without any specific changing on port it's work. 

 http://$(minikube ip):8081

but when i run my app via Kubernetes(minikube) is assign a nodePort in range of 30000-32767. Then i have to call as follow:

http://$(minikube ip):30546

which is not acceptable from my service. Is there any way to map randomly given port to my own defined port? When call second url then i am getting connection refused I also used

kubectl port forward my-service 8081

but still no success.

Upvotes: 0

Views: 451

Answers (3)

J Pod
J Pod

Reputation: 31

One way you can do this in a non-cloud environment is by using the type: NodePort with the external IPs configuration. I have this API service defined here:

apiVersion: v1
kind: Service
metadata:
  labels:
    service: api
  name: api
spec:
  externalIPs:
  - <ip of your node>
  type: NodePort
  ports:
  - name: "http"
    port: 80
    protocol: TCP
    targetPort: 80

Now when the service is applied it will have a defined external IP:

NAME         TYPE        CLUSTER-IP     EXTERNAL-IP     PORT(S)        AGE
api          NodePort    10.43.138.4    <specified IP>  80:30685/TCP   41m

When you use this service's IP address and port combination, traffic is forwarded to the service's pods based on the service's selector. And now I can access the API outside of my cluster curl <specified IP>:80 This method works well when you want control over which specific IPs can be used to access your service.

Upvotes: 0

snnsnn
snnsnn

Reputation: 13688

This answer is not specific to Minikube but applicable to any Kubernetes cluster running inside a docker container.

In order to send a request from the host machine to the Kubernetes pod running in a container, you have to map ports from host machine to all the way to the pod.

Here is how you do it:

  1. Publish the NodePort you want to use inside container to the host machine using --publish or -p.
# Map port 8080 on host machine to 31080 inside the container
docker run -p 8080:31080 ...
  1. Use a custom NodePort when creating the service:
# You need to specify the exposed port as the nodePort value
# Otherwise Kubernetes will generate a random nodePort for you 
kubectl create service nodeport myservice --node-port=31080 --tcp=3000:80

The application inside the pod listens to port 80 which is exposed as a service at port 3000. The traffic received at port 31080 on Kubernetes node will be directed at this service.

The query you send to 8080 on your host machine will follow this path:

Request -> Host Machine -> Docker Container -> Kubernetes Node -> Service -> Pod
               ↑                   ↑                 ↑              ↑         ↑
          localhost:8080         :31080           :31080          :3000      :80

References:

Upvotes: 0

P Ekambaram
P Ekambaram

Reputation: 17679

kubectl port-forward command is incorrect. try below one

kubectl port-forward svc/my-service 8081:8081

then you should be able to access the service at http//:127.0.0.1:8081

Upvotes: 1

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