Where are these ENVVARS coming from???

Start with the Kubernetes Deployment and Service manifests and the container behavior described in the issue. Investigate how Kubernetes exposes Service-related environment variables to pods, then check whether the repository documents or controls this behavior. Done means the source is explained and any needed documentation or code change is identified.

I've got a simple blue/green Kubernetes deployment using this container as described below:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: green-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: green-app
  template:
    metadata:
      labels:
        app: green-app
    spec:
      containers:
      - name: http-https-echo
        image: mendhak/http-https-echo
        ports:
        - containerPort: 8080
        env:
        - name: ECHO_INCLUDE_ENV_VARS
          value: "1"
        - name: APP_COLOR
          value: "GREEN"
---
apiVersion: v1
kind: Service
metadata:
  name: green-app
spec:
  selector:
    app: green-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: blue-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: blue-app
  template:
    metadata:
      labels:
        app: blue-app
    spec:
      containers:
      - name: http-https-echo
        image: mendhak/http-https-echo
        ports:
        - containerPort: 8080
        env:
        - name: ECHO_INCLUDE_ENV_VARS
          value: "1"
        - name: APP_COLOR
          value: "BLUE"
---
apiVersion: v1
kind: Service
metadata:
  name: blue-app
spec:
  selector:
    app: blue-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: color-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
#  tls:
#  - hosts:
#    - '*.com'
  rules:
  - http:
      paths:
      - path: /green
        pathType: Prefix
        backend:
          service:
            name: green-app
            port:
              number: 80
      - path: /blue
        pathType: Prefix
        backend:
          service:
            name: blue-app
            port:
              number: 80

Everything spins up and the /blue and /green endpoints work as they should.

But inside the blue are all of these environment variables referencing the green app (and vice versa)

/app $ env
KUBERNETES_PORT=tcp://172.20.0.1:443
GREEN_APP_PORT_80_TCP=tcp://172.20.144.83:80
KUBERNETES_SERVICE_PORT=443
NODE_VERSION=22.21.0
HOSTNAME=blue-app-64bd4f854f-x9v4j
YARN_VERSION=1.22.22
BLUE_APP_PORT_80_TCP=tcp://172.20.108.198:80
SHLVL=1
HOME=/home/node
ECHO_INCLUDE_ENV_VARS=1
GREEN_APP_SERVICE_HOST=172.20.144.83
BLUE_APP_SERVICE_HOST=172.20.108.198
TERM=xterm
KUBERNETES_PORT_443_TCP_ADDR=172.20.0.1
HTTP_PORT=8080
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
GREEN_APP_PORT=tcp://172.20.144.83:80
KUBERNETES_PORT_443_TCP_PORT=443
GREEN_APP_SERVICE_PORT=80
KUBERNETES_PORT_443_TCP_PROTO=tcp
HTTPS_PORT=8443
BLUE_APP_PORT=tcp://172.20.108.198:80
BLUE_APP_SERVICE_PORT=80
APP_COLOR=BLUE
GREEN_APP_PORT_80_TCP_ADDR=172.20.144.83
KUBERNETES_SERVICE_PORT_HTTPS=443
GREEN_APP_PORT_80_TCP_PORT=80
KUBERNETES_PORT_443_TCP=tcp://172.20.0.1:443
BLUE_APP_PORT_80_TCP_ADDR=172.20.108.198
GREEN_APP_PORT_80_TCP_PROTO=tcp
KUBERNETES_SERVICE_HOST=172.20.0.1
PWD=/app
BLUE_APP_PORT_80_TCP_PORT=80
BLUE_APP_PORT_80_TCP_PROTO=tcp
/app $ 

How can a simple pod that only has 2 environment variables defined (APP_COLOR and ECHO_INCLUDE_ENV_VARS) pickup all of these other variables? Where are they coming from!??!