yttt

base.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: node-hello
  annotations:
    type: "web"
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: demo-container
        image: gcr.io/google-samples/node-hello:1.0
        env:
        - name: DEMO_GREETING
          value: "Hello from the environment"
        - name: DEMO_FAREWELL
          value: "Such a sweet sorrow"
      

http.yaml

#@data/values
---
ports:
- name: http
  containerPort: 80

https.yaml

#@data/values
---
ports:
- name: https
  containerPort: 443

overlay.yaml

#@ load ("@ytt:overlay", "overlay")
#@ load("@ytt:data", "data")

#@overlay/match by=overlay.subset({"kind":"Deployment", "metadata":{"annotations":{"type":"web"}}})
---
spec:
  replicas: #@ data.values.deployment.replicas
  template:
    spec:
      containers:
      #@overlay/match by=overlay.subset({"name":"demo-container"})        
      - 
        #@overlay/match missing_ok=True
        ports:
        #@overlay/match missing_ok=True
        #@ for/end port in data.values.ports:
        - name: #@ port.name
          #@overlay/match missing_ok=True
          port: #@ port.containerPort

replicas.yaml

#@data/values
---
deployment:
  replicas: 3