Example of configuring builtin plugin.

[monopole]

Requires #1532

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[monopole]

@richardmarshall @jbrette PTAL

[jbrette]

This is actually really important. In order to be able to change two images, you need to add multiple transformers. The name of the transformers have to be different, otherwise the resources accumulation will fail

[monopole]

changed to "not-imporant-in-this-example" which is what i meant.
indeed, the names need to be different if using more than one.
maybe just change it to a my-image-transformer or something?

[jbrette]

The syntax of the namespace transformer is kind of misleading. the "metadata/name" is not important but the "metadata/namespace" is. Unlike the other transformer (prefix, suffix), that field is not part of the "spec" of the Transformer but part of the metadata.

[Liujingfang1]

Not every plugin has the config under spec. Even for prefix/suffix transformer, it's prefix and suffix instead of spec. The transformer/generator plugin read the whole k8s styled yaml as its configuration, not only spec field.

[jbrette]

Let me rephrase. All the other transformers have the addditional parameters at the top level....basically the fieldSpecs level, the metadata field is actually irrelevant most of the time.

apiVersion: builtin
kind: LabelTransformer
metadata:
  name: notImportantHere
labels:
  app: myApp
  env: production
fieldSpecs:
  - path: metadata/labels
    create: true

or

apiVersion: builtin
kind: PrefixSuffixTransformer
metadata:
  name: notImportantHere
prefix: baked-
suffix: -pie
fieldSpecs:
  - path: metadata/name

But not for the namespace transformer. The consistent way of doing, should be like this:

apiVersion: builtin
kind: NamespaceTransformer
metadata:
  name: notImportantHere
namespace: test
fieldSpecs:
  - path: metadata/namespace

The other issue is here. The name is actually important for ImageTransformer if you need multiple image transformations. The metadata/namespace is supposed to be completely irrelevant but is not, and the namespace transformer ends up being in a different namespace than all the other transformers. This will be an issue when we will try to apply kustomize on top of the transformer config.yaml

func (kt *KustTarget) configureExternalTransformers() ([]resmap.Transformer, error) {
	ra := accumulator.MakeEmptyAccumulator()
	err := kt.accumulateResources(ra, kt.kustomization.Transformers)
	if err != nil {
		return nil, err
	}
	return kt.pLdr.LoadTransformers(kt.ldr, ra.ResMap())
}

[monopole]

@jbrette yes, the namespace transformer is an outlier.
see comments here: #1280
it's philosophically wrong, but in practice is works and allows for a smaller config file, fwiw.
we should probably 'fix' it if for no other reason than to avoid this kind of confusion/conversation.
Not in this PR though.

[tkellen]

Thank you for this clarification, and for this comment especially: #1280 (comment)!

[monopole]

OK comments addressed. sorry was doing a bunch of pushes to see how it looked since my local md renderer is busted and too lazy to fix at the moment

[monopole]

I'm not happy with the section headings, e.g.

SecretGenerator

Usage via kustomization.yaml

field name: secretGenerator

Usage via plugin

Arguments

Example

could use some improvement, but i'd rather fix in the context of a code generator since it's so tedious to do this.

[Liujingfang1]

@monopole Thank you for this work.

/lgtm