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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