KServe logging

A practical guide to using Kustomize in Kubernetes for managing and modifying labels across multiple resources, demonstrating how to efficiently change labels from ‘app: foo’ to ‘app: bar’ using the commonLabels feature.

In Kubernetes, labels serve as a mechanism to organize and select groupings of objects. They are key-value pairs associated with objects and can be used to apply operations on a subset of objects. Kustomize is a tool that allows us to manage these configurations efficiently.

Let’s consider a project named foo. The project has various Kubernetes objects labeled with app: foo. Now, suppose there is a requirement to change the label to app: bar. This is where Kustomize’s commonLabels feature comes in handy.

Project Name: foo
Existing Label: app: foo
New Label: app: bar

Assume we have a kustomization.yaml file referencing the resources of project foo:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
- deployment.yaml
- service.yaml

To change the label from app: foo to app: bar, we can use the commonLabels field in the kustomization.yaml file:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
- deployment.yaml
- service.yaml

commonLabels:
  app: bar

When you run kustomize build, it will add or override the existing app label with app: bar on every resource and selector specified in the kustomization.yaml file. This ensures that all the resources are uniformly labeled with app: bar, making them identifiable and manageable under the new label.