Can't Access Kubernetes Service Exposed via NodePort - docker

Question

I'm using minikube to test kubernetes on latest MacOS.
Here are my relevant YAMLs:
namespace.yml
apiVersion: v1
kind: Namespace
metadata:
name: micro
labels:
name: micro
deployment.yml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: adderservice
spec:
replicas: 1
template:
metadata:
labels:
run: adderservice
spec:
containers:
- name: adderservice
image: jeromesoung/adderservice:0.0.1
ports:
- containerPort: 8080
service.yml
apiVersion: v1
kind: Service
metadata:
name: adderservice
labels:
run: adderservice
spec:
ports:
- port: 8080
name: main
protocol: TCP
targetPort: 8080
selector:
run: adderservice
type: NodePort
After running minikube start, the steps I took to deploy is as follows:
kubectl create -f namespace.yml to create the namespace
kubectl config set-context minikube --namespace=micro
kubectl create -f deployment.yml
kubectl create -f service.yml
Then, I get the NodeIP and NodePort with below commands:
kubectl get services to get the NodePort
$ kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
adderservice NodePort 10.99.155.255 <none> 8080:30981/TCP 21h
minikube ip to get the nodeIP
$ minikube ip
192.168.99.103
But when I do curl, I always get Connection Refused like this:
$ curl http://192.168.99.103:30981/add/1/2
curl: (7) Failed to connect to 192.168.99.103 port 30981: Connection refused
So I checked node, pod, deployment and endpoint as follows:
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
minikube Ready master 23h v1.13.3
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
adderservice-5b567df95f-9rrln 1/1 Running 0 23h
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
adderservice 1 1 1 1 23h
$ kubectl get endpoints
NAME ENDPOINTS AGE
adderservice 172.17.0.5:8080 21h
I also checked service list from minikube with:
$ minikube service -n micro adderservice --url
http://192.168.99.103:30981
I've read many posts regarding accessing k8s service via NodePorts. To my knowledge, I should be able to access the app with no problem. The only thing I suspect is that I'm using a custom namespace. Will this cause the access issue?
I know namespace will change the DNS, so, to be complete, I ran below commands also:
$ kubectl exec -ti adderservice-5b567df95f-9rrln -- nslookup kubernetes.default
Server: 10.96.0.10
Address: 10.96.0.10#53
Name: kubernetes.default.svc.cluster.local
Address: 10.96.0.1
$ kubectl exec -ti adderservice-5b567df95f-9rrln -- nslookup kubernetes.micro
Server: 10.96.0.10
Address: 10.96.0.10#53
Non-authoritative answer:
Name: kubernetes.micro
Address: 198.105.244.130
Name: kubernetes.micro
Address: 104.239.207.44
Could anyone help me out? Thank you.

Answer 1

The error Connection Refused mostly means that the application inside the container does not accept requests on the targeted interface or not mapped through the expected ports.
Things you need to be aware of:
Make sure that your application bind to 0.0.0.0 so it can receive requests from outside the container either externally as in public or through other containers.
Make sure that your application is actually listening on the containerPort and targetPort as expect
In your case you have to make sure that ADDERSERVICE_SERVICE_HOST equals to 0.0.0.0 and ADDERSERVICE_SERVICE_PORT equals to 8080 which should be the same value as targetPort in service.yml and containerPort in deployment.yml

Answer 2

Not answering the question but if someone who googled comes here like me who faced the same issue. Here is my solution for the same problem.
My Mac System IP and minikube IP are different.
So localhost:port didn't work instead try getting IP
minikube ip
Later, use that IP:Port to access the app and it works.

Answer 3

Check if service is really listening on 8080.
Try telnet within the container.
telnet 127.0.0.1 8080
.
.
.
telnet 172.17.0.5 8080