I am running my application on Kubernetes that was provided to me as a black box docker image that runs with a bunch of env vars, volume mounts and (a little more unconventionally) using host port. I discovered - with a lot of pain and sweat - as expected, I can't have more than one pod in my deployment if I ever wish to see the host port function again.

Two things are clear to me: 1. I need to add more pod replicas & 2. I can't use an ingress controller (need to have a separate external IP).

Other points of information are:

• I am using an external IP (quick solution is a LB service)
• When I enable host port on Kubernetes, everything works like a charm
• I am using a single tls certificate that is stored in the PVC that will be shared between my pods.
• When I disable host port, increase number of replicas and pretend it should work, the pods start running successfully, but the application can't be reached the way I reach it normally, as if it never hears what comes from the user through the loadbalancer (hence I thought setting up a NAT might have something to do with a solution??)

Things I tried:

• Use NodePort to expose the containerPort, and add replicas (& maybe then set up an ingress for loadbalancing). Problems with this: The port I am trying to map to the host is 80, and it's out range. I need to allow TCP and UDP through, which will require to create 2 separate services each with a different nodePort.
• Expose any possible port I can think of that might be used through a Loadbalancer service. Problem with this is that the user cannot reach the app for some reason.

My yaml files look something like the following:

deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: x
  name: x
  labels:
    app: x
spec:
  replicas: 1
  selector:
    matchLabels:
      app: x
  template:
    metadata:
      labels:
        app: x
    spec:
      # hostNetwork: true
      containers:
      - name: x
        image: x
        env:
        ...
        volumeMounts:
        ...
        ports:
        - containerPort: 80
      volumes:
      ...
      imagePullSecrets:
      - name: x

service.yaml

apiVersion: v1
kind: Service
metadata:
  labels:
    app: x
  namespace: x
  name: x
spec:
  type: LoadBalancer
  loadBalancerIP: x
  ports:
  - name: out
    port: 8081
    targetPort: 8081
    protocol: TCP
  - name: node
    port: 80
    targetPort: 80
    protocol: TCP
  selector:
    app: x
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: x
  namespace: x
  name: x
spec:
  type: LoadBalancer
  loadBalancerIP: x
  ports:
  - name: out
    port: 8081
    targetPort: 8081
    protocol: UDP
  - name: node
    port: 80
    targetPort: 80
    protocol: UDP
  selector:
    app: x

Problem is, what is the best practice / solution to replace host port netwroking safely?