How to expose a Kubernetes service externally using NodePort - kubernetes

Question

I run the CoreOS k8s cluster on Mac OSX, which means it's running inside VirtualBox + Vagrant
I have in my service.yaml file:
spec:
type: NodePort
When I type:
kubectl get services
I see:
NAME CLUSTER_IP EXTERNAL_IP PORT(S) SELECTOR
kubernetes 10.100.0.1 <none> 443/TCP <none>
my-frontend 10.100.250.90 nodes 8000/TCP name=my-app
What is the "nodes" external IP? How do I access my-frontend externally?

Answer 1

In addition to "NodePort" types of services there are some additional ways to be able to interact with kubernetes services from outside of cluster:
Use service type "LoadBalancer". It works only for some cloud providers and will not work for virtualbox, but I think it will be good to know about that feature. Link to the documentation
Use one of the latest features called "ingress". Here is description from manual "An Ingress is a collection of rules that allow inbound connections to reach the cluster services. It can be configured to give services externally-reachable urls, load balance traffic, terminate SSL, offer name based virtual hosting etc.". Link to the documentation
If kubernetes is not strict requirements and you can switch to latest openshift origin (which is "kubernetes on steroids") you can use origin feature called "router".
Information about openshift origin.
Information about openshift origin routes

Answer 2

I assume you are using MiniKube for Kubernetes. In such case, to identify your node ip address, use the following command:
.\minikube.exe ip
If the exposed service is of type=Nodeport, to check the exposed port use the following command:
.\kubectl.exe describe service <service-name>
Check for Node port in the result. Also, if you want to have all these details via nice UI, then you can launch the Kubernetes Dashboard present at the following address:
<Node-ip>:30000

Answer 3

The easiest way to get the host ports is kubectl describe services my-frontend.
The node port will be displayed.
Also you can check the api:
api/v1/namespaces/{namespace_name}/services/{service_name}
or list all:
api/v1/namespaces/default/services
Last, you can chose a fixed nodePort in the service.yml

Answer 4

Here is the doc on node addresses: http://kubernetes.io/docs/admin/node/#addresses
You can specify the port number of nodePort when you specify the service. If you didn't manually specify a port, system will allocate one for you. You can kubectl get services -o yaml and find the port at spec.ports[*].nodePort, as suggested in the doc here: https://github.com/kubernetes/kubernetes/blob/master/docs/user-guide/services.md#type-nodeport
And you can access your front-end at {nodes' external addresses}:{nodePort}
Hope this helps.