I want to communicate with containers which are in the same pod programmatically.

So,I decided to set the ports of the auxiliary containers (bar1-container and bar2-container in this example) as environment variables of the primary container (i.e. foo-container).

However, I could not figure out how to pass the exposed ports of the auxiliary ports can be implicitly in the .yaml file for my deployment configuration:

apiVersion:  apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: test-deployment
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: web
        tier: frontend
    spec:
      containers:
      # Only container to be exposed outside the pod
      - name: foo-container
        image: foo
        env:
        - name: BAR_1_PORT
          # HOW TO GET PORT HERE IMPLICITLY ???
          value: XXXX 
        - name: BAR_2_PORT
          # HOW TO GET PORT HERE IMPLICITLY ???
          value: XXXX
        ports:
        - name: https
          containerPort: 443
        - name: http
          containerPort: 80
      # SubContainer 1
      - name: bar1-container
        image: bar1
      # SubContainer 2
      - name: bar2-container
        image: bar2

I wonder if there is a way to use the ports like ${some-variable-or-so-here} instead of 5300, 80, 9000 or whichever port is exposed from the container.

P.S: I deliberately did not specify ports or containerPort values of auxiliary containers in the yaml configuatin above as they will not be exposed outside the pod.