config.yaml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: example-ingress1
  labels:
    ingress.kubernetes.io/rewrite-target: /
    keep: me
    foo: bar
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: example-ingress1
  labels:
    foo: bar

overlay.yaml

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

#@ def matcher():
kind: Ingress
metadata:
  name: example-ingress1
  labels:
    foo: bar
#@ end

#@overlay/match by=overlay.subset(matcher()),expects=2
#@overlay/remove
---