https://github.com/andy2046/k8s-custom-resource-watch

watch for custom resource
https://github.com/andy2046/k8s-custom-resource-watch

controller crd custom-resource-definition kubernetes

Last synced: about 2 months ago
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watch for custom resource

• Host: GitHub
• URL: https://github.com/andy2046/k8s-custom-resource-watch
• Owner: andy2046
• License: bsd-3-clause
• Created: 2019-05-02T10:07:22.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2019-05-12T12:49:26.000Z (over 5 years ago)
• Last Synced: 2024-11-16T01:19:24.323Z (2 months ago)
• Topics: controller, crd, custom-resource-definition, kubernetes
• Language: Go
• Homepage: https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/#delete-a-customresourcedefinition
• Size: 4.76 MB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# k8s-custom-resource-watch

> a custom K8s controller example to watch for the creation, update, deletion of user defined custom resources.

## Workflow

### 1 Define custom resource

#### 1.1 define API group name / Version / Resource name

* The API group name `nokube.xyz`

* The Version `v1`

* Resource name `customresource`

#### 1.2 create the directory structure

```sh

mkdir -p pkg/apis/customresource/v1

```

#### 1.3 add API group name const in register file

```sh

touch pkg/apis/customresource/register.go

```

> package has the same name as the custom resource

```go

package customresource

// GroupName for customresource

const GroupName = "nokube.xyz"

```

#### 1.4 create the resource structs

```sh

touch pkg/apis/customresource/v1/types.go

```

> `// +[=value]` are indicators for code generator

> `+genclient` — generate a client for the package

> `+genclient:noStatus` — when generating the client, there is no status stored for the package

> `+k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object` — generate deepcopy logic (required) implementing the runtime.Object interface (for both `CustomResource` and `CustomResourceList`)

#### 1.5 create a doc source file for the package

```sh

touch pkg/apis/customresource/v1/doc.go

```

```go

// +k8s:deepcopy-gen=package

// +groupName=nokube.xyz

package v1

```

> `// +groupName=nokube.xyz` inform the generator what the API group name is

> `// +k8s:deepcopy-gen=package` deepcopy should be generated for all types in the package

#### 1.6 add functions to handle adding types to the schemes

```sh

touch pkg/apis/customresource/v1/register.go

```

### 2 Run the code generator

run `code-gen.sh` shell script to do all the heavy lifting via `k8s.io/code-generator` package

### 3 Wire up the generated code

#### 3.1 to return custom resource clientset instance to interact with `CustomResource` in `main.go`

```go

// retrieve the Kubernetes cluster client from outside of the cluster.

func getKubeClient() (kubernetes.Interface, resourceclientset.Interface) {

	var kubeConfigPath string

	if !inCluster {

		// resolve path to `$HOME/.kube/config`

		kubeConfigPath = path.Join(userHomeDir(), "/.kube/config")

	}

	config, err := clientcmd.BuildConfigFromFlags("", kubeConfigPath)

	if err != nil {

		logger.Fatalf("BuildConfigFromFlags: %v", err)

	}

	client, err := kubernetes.NewForConfig(config)

	if err != nil {

		logger.Fatalf("client NewForConfig: %v", err)

	}

	resourceClient, err := resourceclientset.NewForConfig(config)

	if err != nil {

		logger.Fatalf("resourceClient NewForConfig: %v", err)

	}

	logger.Println("Successfully get k8s client")

	return client, resourceClient

}

```

#### 3.2 to return custom resource informer instance in `controller.go`

```go

// New creates a Controller instance.

func New(client kubernetes.Interface, resourceClient resourceclientset.Interface) *Controller {

	informer := resourceinformerV1.NewCustomResourceInformer(

		resourceClient,

		nameSpace,

		0,

		cache.Indexers{},

    )

    

    // ...

}

```

### 4 Add Custom Resource Definition

```sh

mkdir crd

# touch crd/customresource.yml

kubectl apply -f crd/customresource.yml

kubectl get customresourcedefinition

```

### 5 Run the controller

```sh

go run main.go

# touch customresource-deploy.yml

kubectl apply -f customresource-deploy.yml

kubectl get CustomResource

```

### 6 Clean up

```sh

kubectl delete CustomResource example-customresource

kubectl delete -f crd/customresource.yml

```