Kustomize: Automatically add environment metadata label to each kubernetes object

I need to add a metadata label to every object in a kubernetes manifest; extraLabel: TEST-1234567890. The label value varies per test/acc/prod environment. I use the following patch configuration to apply the label to each kubernetes object, per environment:

test/kustomize.yml:

resources:
  - ../base
patches:
  - path: patch-test.yml

test/patch-test.yml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: some-deployment
  labels:
    extraLabel: TEST-1234567890
spec:
  template:
    metadata:
      labels:
        extraLabel: TEST-1234567890

---
apiVersion: v1
kind: Service
metadata:
  name: some-service
  labels:
    extraLabel: TEST-1234567890
---

...etc

This is a bit cumbersome because each kubernetes object has to be manually added to the patch manifest for each environment, and the label value is duplicated across multiple patch files. I am looking for a way to have kustomize automatically apply the label (and value, varying per environment) to each kubernetes object.

I have tried creating a patch manifest containing a commonLabels section, however the use of commonLabels resulted in the label also being applied to selector.matchLabels and labelSelector.matchLabels, which is an undesired outcome. Attempting to patch the commonLabels section using:

  - target:
      kind: Deployment
    patch: |-
      - op: remove
        path: /spec/selector/matchLabels/extraLabel
... etc

Did not work. Would anyone have a resolution to this matter?

For anyone interested, I managed to add labels to every object by using the labels[].pairs section.

test/kustomize.yml:

resources:
  - ../base

labels:
  - pairs:
      extraLabel: TEST-1234567890
      someOtherLabel: abc
    includeTemplates: true

includeTemplates is set to true to add the labels to template sections as well (such as spec.template.metadata.labels)