kustomize/examples/transformerconfigs/crd/README.md

Transformer Configurations - CRD

This tutorial shows how to add transformer configurations to support a CRD type.

Get Default Config

Get the default transformer configurations by

kustomize config save -d ~/.kustomize/config

The default configurations are save in directory ~/.kustomize/config as several files

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

Add Config for a CRD

All transformers will be involved for a CRD type. The default configurations already include some common fieldSpec 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

Thus those fieldSpec don't need to be added to support a CRD type. Consider a CRD type 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 following file to configure the transformers for the above fields

cat > ~/.kustomize/config/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 kustomization with a MyKind instance.

DEMO_HOME=$(mktemp -d)

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

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

Run kustomize build with customized transformer configurations and verify that the namereference is correctly resolved.

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

Run kustomize build with customized transformer configurations and verify that the vars correctly resolved.

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

To understand this better, compare the output using default transformer configurations.

diff \
 <(kustomize build $DEMO_HOME) \
 <(kustomize build $DEMO_HOME -t ~/.kustomize/config ) |\
 more

The difference output should look something like

20,21c20,21
<     action: $(BEE_ACTION)
<     name: bee
---
>     action: fly
>     name: test-bee
25c25
<     - $(BEE_ACTION)
---
>     - fly
28c28,30
<     name: crdsecret
---
>     name: test-crdsecret
>   selectors:
>     foo: bar