Replica数を変えたい

input.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: demo
  name: demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: demo
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - image: ghcr.io/making/hello-tanzu
        name: hello-tanzu

overlay.yml

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

#@overlay/match by=overlay.subset({"kind":"Deployment", "metadata": {"name": "demo"}})
---
spec:
  replicas: 3