Namespace fieldPath missing

[fhalde]

Can someone tell why kustomize complains that the fieldPath .metadata.namespace is missing even though I set the "namespace" in my kustomization.yaml ?

.
├── prod
│   ├── flink.yaml
│   └── kustomization.yaml
├── base
│   ├── flink.yaml
│   └── kustomization.yaml
├── components
│   └── dns
│       └── kustomization.yaml
└── app
    ├── flink.yaml
    └── kustomization.yaml

I have a base kustomize with a single resource

base/flink.yaml
apiVersion: flink.apache.org/v1beta1
kind: FlinkDeployment
metadata:
  name: flinkapp
spec:
  imagePullPolicy: Always
  flinkVersion: v1_18
  flinkConfiguration:
    taskmanager.numberOfTaskSlots: "1"

base/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- flink.yaml

I have a prod overlay that adds an ingress to the flink deployment

prod/flink.yaml
apiVersion: flink.apache.org/v1beta1
kind: FlinkDeployment
metadata:
  name: flinkapp
spec:
  ingress:
   template: "{{name}}.mydns.com"
   className: "nginx"
   annotations:
     external-dns.alpha.kubernetes.io/hostname: "{{name}}.mydns.com"

prod/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- ./../base

patches:
- path: flink.yaml

The "app", uses the prod overlay, adds a namespace, does a irrelevant patch to the spec and refers a component that alters the dns entry in ingress

app/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization


resources:
- ./../prod

namespace: foobar

patches:
- path: flink.yaml

components:
- ./../components/dns

The component is basically using "replacements" to alter the ingress

components/dns/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1alpha1
kind: Component

replacements:
  - source:
      kind: FlinkDeployment
      name: flinkapp
      fieldPath: .metadata.namespace
    targets:
      - select:
          kind: FlinkDeployment
        fieldPaths:
          - .spec.ingress.annotations.[external-dns.alpha.kubernetes.io/hostname]
        options:
          delimiter: '.'
          index: 0
          create: true

For some reason, kustomize is complaining that .medata.namespace does not exist. Even though in the app kustomization.yaml I've set the "namespace"

Am I missing something? The DNS subdomain HAS to be that of the provided namespace which is only known in the "app" kustomization

[project0]

I have the exact same problem. Apparently namespace transformer is applied AFTER components and replacement.

[sda399]

it's about the build workflow. Which is to my understanding accumulates resources and components first, then runs generators, transformers and validators.

So you will not have access to the namespace during the replacement run, because it is located in a component.
replacement works fine if put in the kustomization.yaml

[project0]

For anyone else stumbling across, this is the order of execution for the bulitins:

kustomize/api/internal/plugins/builtinhelpers/builtins.go

Lines 14 to 34 in 447a609

	const (
	Unknown BuiltinPluginType = iota
	AnnotationsTransformer
	ConfigMapGenerator
	IAMPolicyGenerator
	HashTransformer
	ImageTagTransformer
	LabelTransformer
	NamespaceTransformer
	PatchJson6902Transformer
	PatchStrategicMergeTransformer
	PatchTransformer
	PrefixSuffixTransformer
	PrefixTransformer
	SuffixTransformer
	ReplicaCountTransformer
	SecretGenerator
	ValueAddTransformer
	HelmChartInflationGenerator
	ReplacementTransformer
	)