Accessing Kubernetes pods/services through one IP (Preferably Master Node) - kubernetes

Question

I have a local Kubernetes installation with a master node and two worker nodes. Is there a way to access all services/pods that will be installed on Kubernetes through master node's ip?
What i mean is say i have a test service running on port 30001 on each worker and i want to access this service like http://master-node:30001. Every help is appreciated.

Answer 1

You can use "the proxy verb" to acces nodes, pods, or services through the master. Only HTTP and HTTPS can be proxied. See these docs and these docs.

Answer 2

There are some ways to do it:
Define a NodePort Kubernetes service
Use kubefwd or port forwarding command
Use proxy command (Only support HTTP & HTTPS)
In this answer, I explain how to define a NodePort Service.
The NodePort service is explained as below (Service - Kubernetes)
NodePort: Exposes the Service on each Node's IP at a static port (the NodePort). A ClusterIP Service, to which the NodePort Service routes, is automatically created. You'll be able to contact the NodePort Service, from outside the cluster, by requesting :.
Here is an example of the NodePort service for PostgreSQL:
apiVersion: v1
kind: Service
metadata:
name: postgres
namespace: postgres
labels:
app: postgres
spec:
ports:
- port: 5432
type: NodePort
selector:
app: postgres
The port field stands for both service port and default target port. There is also a nodePort field that allows you to choose the port to access the service from outside of the cluster (via the node's IP and the nodePort)
To view the node's Port (if you don't specify it from the manifest), you can run the command:
kubectl get services -n postgres
The output should look similar to:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
postgres NodePort 10.96.156.75 <none> 5432:30864/TCP 6d9h app=postgres
In this case, the nodePort is 30864, this is the port to access to the service from outside the cluster.
To find out the node's IP, the command to use is:
kubectl get nodes -o wide
The output should look similar to:
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
homedev-control-plane Ready master 30d v1.19.1 172.18.0.2 <none> Ubuntu Groovy Gorilla (development branch) 5.9.1-arch1-1 containerd://1.4.0
If what you need is the IP only:
kubectl get nodes -o wide --no-headers | awk '{print $6}'
In this case, the node's IP is 172.18.0.2. Hence to connect to the Postgres in the local Kubernetes cluster from your host machine, the command would look like this:
psql -U postgres -h 172.18.0.2 -p 30864-d postgres