Optional pipeline steps: enabled=false boolean

[karlkfi]

I want to be able to ship kpt packages with optional features, but kpt doesn't have any conditional code blocks.

One way to satisfy this requirement would be to add an enabled boolean to the pipeline step syntax in kpt v1. This would allow kptfiles to include steps that are disabled by default, allowing users to enable them with a one-line change.

An optional additional enhancement would be a CLI command for toggling steps by name:

kpt pipeline step enable "step-name"

[bgrant0607]

Sounds useful.

I wanted something similar for kustomize at some point.

[karlkfi]

Hypothetical example:

Kptfile:

pipeline:
  mutators:
  - image: gke-security-group
    configMap:
      domain: environblueprint.joonix.net
      parent: gke-security-groups
      create: true
      groups:
      - group1
      - group2
    enabled: false

This example would call a function to set the spec.authenticatorGroupsConfig.securityGroup on any ContainerCluster in the package, and make the group in Google Workspaces if it didn't already exist, but would be disabled by default, because not all users of the GKE clusters have a Google Workspace or Cloud Identity subscription.

This would allow reducing the dependencies of the package by default and making groups an optional dependency.

[frankfarzan]

The use case makes sense to me. This will be a post-v1 additive change. Exact design for schema and CLI porcelain (if any) TBD.

[bgrant0607]

@droot mentioned a use case for this in #2284