Set the namespace special for one resource

docs.yaml

---
kind: Deployment
metadata:
  name: A
---
kind: Deployment
metadata:
  name: B
---
kind: Deployment
metadata:
  name: B
---
kind: ConfigMap
metadata:
  name: fluentd-config

in-fluentd-namespace-except-configmap.yaml

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

#@ fluentdConfigMap = overlay.subset({"kind": "ConfigMap", "metadata": {"name": "fluentd-config"}})

#@overlay/match by=fluentdConfigMap
---
metadata:
  #@overlay/match missing_ok=True
  namespace: kube-system

#@overlay/match by=overlay.not_op(fluentdConfigMap), expects="1+"
---
metadata:
  #@overlay/match missing_ok=True
  namespace: fluentd