set-labels

Overview #

The set-labels function adds a list of labels to all resources. It’s a common practice to add a set of labels for all the resources in a package. Kubernetes has some recommended labels.

For example, labels can be used in the following scenarios:

• Identify the KRM resources by querying their labels.
• Set labels for all resources within a package (e.g. environment=staging).

You can learn more about labels here.

Usage #

This function can be used with any KRM function orchestrators (e.g. kpt).

For each label, the function adds it if it doesn’t exist. Otherwise, it replaces the existing label with the same name.

In addition to updating the metadata.labels field for each resource, the function will also update the selectors that target the labels by default. e.g. the selectors for Service will be updated to include the desired labels.

This function can be used both declaratively and imperatively.

FunctionConfig #

There are 2 kinds of functionConfig supported by this function:

• ConfigMap
• A custom resource of kind SetLabels

To use a ConfigMap as the functionConfig, the desired labels must be specified in the data field.

To add 2 labels color: orange and fruit: apple to all resources, we use the following functionConfig:

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  color: orange
  fruit: apple

To use a SetLabels custom resource as the functionConfig, the desired labels must be specified in the labels field. Sometimes you have resources ( especially custom resources) that have labels or selectors fields in fields other than the defaults, you can specify such label fields using additionalLabelFields. It will be used jointly with the defaults.

additionalLabelFields has following fields:

• group: Select the resources by API version group. Will select all groups if omitted.
• version: Select the resources by API version. Will select all versions if omitted.
• kind: Select the resources by resource kind. Will select all kinds if omitted.
• path: Specify the path to the field that the value needs to be updated. This field is required.
• create: If it’s set to true, the field specified will be created if it doesn’t exist. Otherwise, the function will only update the existing field.

To add 2 labels color: orange and fruit: apple to all built-in resources and the path data.selector in MyOwnKind resource, we use the following functionConfig:

apiVersion: fn.kpt.dev/v1alpha1
kind: SetLabels
metadata:
  name: my-config
labels:
  color: orange
  fruit: apple
additionalLabelFields:
  - path: data/selector
    kind: MyOwnKind
    create: true