How to expose multiple TCP Servers through one load balancer

Question

I have multiple deployments which run pods which run TCP servers. These TCP servers listen all on port 9999

Currently each deployment has their own load balancer service, which results in a different IP for each deployment.

However I would like to have one IP address to expose the deployments and only distinguish by port.

So for example:

<public-ip>:9001 -> deployment 1
<public-ip>:9002 -> deployment 2
<public-ip>:9003 -> deployment 3

I have read about Ingress but the docs state that

An Ingress does not expose arbitrary ports or protocols. Exposing services other than HTTP and HTTPS to the internet typically uses a service of type Service.Type=NodePort or Service.Type=LoadBalancer.

So that seems to be not an option.

For context the kubernetes is hosted in azure in an vnet and only needs to be accessed from within this vnet.

Answer 1

Functionality ingress depends on the controller implementation that you are using. For example nginx ingress controller supports TCP/UDP proxy as documented here

The next example shows how to expose the service example-go running in the namespace default in the port 8080 using the port 9000

apiVersion: v1
kind: ConfigMap
metadata:
  name: tcp-services
  namespace: ingress-nginx
data:
  9000: "default/example-go:8080"

If TCP/UDP proxy support is used, then those ports need to be exposed in the Service defined for the Ingress.

apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  type: LoadBalancer
  ports:
    - name: http
      port: 80
      targetPort: 80
      protocol: TCP
    - name: https
      port: 443
      targetPort: 443
      protocol: TCP
    - name: proxied-tcp-9000
      port: 9000
      targetPort: 9000
      protocol: TCP
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx