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CRD Code Generation

Starting in Kubernetes 1.8, code can be generated for all CRDs with the same generators that are used for the built-in K8s resources. This takes CRDs to the next level of following the same patterns as in-tree resources. For more background on the code generation, see the deep dive.

Directory Structure

First, let's understand the directory structure that is expected with the CRD code generation. There are two folders at the root level of the pkg directory:

  • apis: Contains types and basic implementation of the CRDs. Some code for the CRD types is generated here.
  • client: Generated code for strongly typed clients

Create your types

Before you can generate any code, you will need to put the basic code in place for your CRD. Here are the steps followed when creating this sample walkthrough.

NOTE: Blank lines are important to the code generator. Until they fix the parsing issues, it will be best if you leave the blank lines in place.

  1. Create the pkg/apis/myproject/v1alpha1 folder.
  2. Create doc.go with the following contents. Notice the instructions for the code generator.
// +k8s:deepcopy-gen=package,register

// Package v1 is the v1 version of the API.
// +groupName=myproject
package v1alpha1
  1. Create types.go with the definition for your types. Each type will need the code generation attributes.
// +genclient
// +genclient:noStatus
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

type Sample struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata"`
	Spec              SampleSpec `json:"spec"`
}
  1. Create register.go with the CRD definition that will register your CRD type. No code generation attributes are needed.

Run the code generator

During a build process, it is recommended to run the code generator to make sure you always have the latest fixes for the code generation. For this sample, a script codegen.sh is provided to simplify the call to the k8s code generation script that is found under the vendor folder.

# Run the code generator
./codegen.sh

This script will generate the following artifacts:

  • apis/myproject/v1alpha1/zz_generated.deepcopy.go: The deep copy methods for the CRD types necessary in K8s 1.8
  • client/clientset/versioned: Many files are generated under this folder for access by a strongly typed client.