kyverno/samples/AddDefaultLabels.md

Add default labels to objects

Labels are important pieces of metadata that can be attached to just about anything in Kubernetes. They are often used to tag various resources as being associated in some way. Kubernetes has no ability to assign a series of "default" labels to incoming objects. This sample policy shows you how to assign one or multiple labels by default to any object you wish. Here it shows adding a label called custom-foo-label with value my-bar-default to resources of type Pod, Service, and Namespace but others can be added or removed as desired.

Alternatively, you may wish to only add the custom-foo-label if it is not already present in the creation request. For example, if a user/process submits a request for a new Namespace object and the manifest already includes the label custom-foo-label with a value of custom-value, Kyverno can leave this label untouched which results in the newly-created object having the label custom-foo-label=custom-value instead of my-bar-default. In order to do this, enclose the label in the sample manifest in +() so the key name becomes +(custom-foo-label). This conditional instructs Kyverno to only add the label if absent.

Policy YAML

add_default_labels.yaml

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: add-default-labels
spec:
  background: false
  rules:
  - name: add-default-labels
    match:
      resources:
        kinds:
        - Pod
        - Service
        - Namespace
    mutate:
      patchStrategicMerge:
        metadata:
          labels:
            custom-foo-label: my-bar-default