type name -> Kluster

group -> utsab.dev

version -> v1alpha1

• The directory will look like

pkg/apis/utsab.dev/v1alpha1 --> inside with there should be types.go

• Create main.go in the outside directory

• Since the structs created in types.go are only the go structs and not necessarily a kubernetes object

• Hence to convert the go struct to kubernetes object, we use register.go file.

• Generate

  Deep copy objects
  
  ClientSet
  
  Informers
  
  Listers
  

• We can use codegenerator project for this.

doc.go file

• Types are the ways to control the behaviour of the code generator

  • global tags - specified in doc.go
  • local tags - specify tags in types.go

• Even though the struct is registered in Kubernetes, CRD should be generated, so that kubernetes can access the struct.

use controller-gen

Registering and creating CRD should go in parallel

• create folder as controller inside pkg folder

• create a file kluster.go

• call the digitalocean api using Spec

• create do->digitalocean folder under pkg and create a file

• We want to add other fields to the file by itself using controller like configuring clusterID, progress, kubeconfig on the yaml file without explicitly added by the user.

• For this status subresource is useful.

apiVersion kind metadata: spec: // only should be updated by user ... ... status: // only should be updated by controller or operator clusterID progress kubeconfig

• To obtain this, we use subresource making status and spec as the subresource gives an endpoint to which can be mapped a RBAC.

Every resource has an endpoint

resource apis/apps/v1/namespaces/<ns>/deployments v1/namespaces/<ns>/pods/<podname>/

Subresources pods --> logs, describe, exec

• Endpoint for the subresource v1/namespaces/<ns>/pods/<podname>/logs

• Suppose this is the role by which the operator is going to run role-test: resources: Kluster/status

• This particular role will only allow operator to update the status part.