merge-by-key-only.yaml

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

#@ def key_overlay():
metadata:
  name: simple-app
#@ end

#@overlay/match by=overlay.subset(key_overlay()),when="1+"
---
spec:
  fetch:
  #@overlay/match by=lambda _,l,r: "git" in l
  - git:
      #@overlay/match missing_ok=True
      subPath: config-step-2-template

---

apiVersion: kappctrl.k14s.io/v1alpha1
kind: App
metadata:
  name: simple-app
  namespace: default
spec:
  serviceAccountName: default-ns-sa
  fetch:
  - git:
      url: https://github.com/vmware-tanzu/carvel-simple-app-on-kubernetes
      ref: origin/develop
  template:
  - ytt: {}
  deploy:
  - kapp: {}