kustomize/examples/transformerconfigs/crd/README.md

Supporting Custom Resources (defined by a CRD)

This tutorial shows how to add transformer configurations to support a custom resource.

Create a workspace by

DEMO_HOME=$(mktemp -d)

Get the native config as a starting point

Get the default transformer configurations using this command:

kustomize config save -d $DEMO_HOME/kustomizeconfig

The default configurations are saved in the directory $DEMO_HOME/kusotmizeconfig as several files

commonannotations.yaml
commonlabels.yaml
nameprefix.yaml
namereference.yaml
namespace.yaml
varreference.yaml

These files contain the field specifications for native resources that transformation directives like namePrefix, commonLabels, etc. need to do their work.

These default configurations already include some common field specifictions for all types:

• nameprefix is added to .metadata.name
• namespace is added to .metadata.namespace
• labels is added to .metadata.labels
• annotations is added to .metadata.annotations

Adding a custom resource

Consider a CRD of kind MyKind with fields

• .spec.secretRef.name reference a Secret
• .spec.beeRef.name reference an instance of CRD Bee
• .spec.containers.command as the list of container commands
• .spec.selectors as the label selectors

Add the following file to configure the transformers for the above fields

cat > $DEMO_HOME/kustomizeconfig/mykind.yaml << EOF

commonLabels:
- path: spec/selectors
  create: true
  kind: MyKind

nameReference:
- kind: Bee
  fieldSpecs:
  - path: spec/beeRef/name
    kind: MyKind
- kind: Secret
  fieldSpecs:
  - path: spec/secretRef/name
    kind: MyKind

varReference:
- path: spec/containers/command
  kind: MyKind
- path: spec/beeRef/action
  kind: MyKind

EOF

Apply config

Create a file with some resources that includes an instance of MyKind:

cat > $DEMO_HOME/resources.yaml << EOF
apiVersion: v1
kind: Secret
metadata:
  name: crdsecret
data:
  PATH: YmJiYmJiYmIK
---
apiVersion: v1beta1
kind: Bee
metadata:
  name: bee
spec:
  action: fly
---
apiVersion: jingfang.example.com/v1beta1
kind: MyKind
metadata:
  name: mykind
spec:
  secretRef:
    name: crdsecret
  beeRef:
    name: bee
    action: \$(BEE_ACTION)
  containers:
  - command:
    - "echo"
    - "\$(BEE_ACTION)"
    image: myapp
EOF

Create a kustomization referring to it:

cat > $DEMO_HOME/kustomization.yaml << EOF
resources:
- resources.yaml

namePrefix: test-

commonLabels:
  foo: bar

vars:
- name: BEE_ACTION
  objref:
    kind: Bee
    name: bee
    apiVersion: v1beta1
  fieldref:
    fieldpath: spec.action
EOF

Use the customized transformer configurations by specifying them in the kustomization file:

cat >> $DEMO_HOME/kustomization.yaml << EOF
configurations:
- kustomizeconfig/mykind.yaml
- kustomizeconfig/commonannotations.yaml
- kustomizeconfig/commonlabels.yaml
- kustomizeconfig/nameprefix.yaml
- kustomizeconfig/namereference.yaml
- kustomizeconfig/namespace.yaml
- kustomizeconfig/varreference.yaml
EOF

Run kustomize build and verify that the namereference is correctly resolved.

test 2 == \
$(kustomize build $DEMO_HOME | grep -A 2 ".*Ref" | grep "test-" | wc -l); \
echo $?    

Run kustomize build and verify that the vars correctly resolved.

test 0 == \
$(kustomize build $DEMO_HOME | grep "BEE_ACTION" | wc -l); \
echo $?