Merge pull request #46242 from ahmetb/clientgo-examples/crud-deployment

Automatic merge from submit-queue

clientgo/examples: Add CRUD Deployment sample

hack/.linted_packages

@@ -364,6 +364,7 @@ staging/src/k8s.io/apiserver/plugin/pkg/authenticator/password
 staging/src/k8s.io/apiserver/plugin/pkg/authenticator/password/allow
 staging/src/k8s.io/apiserver/plugin/pkg/authenticator/request/basicauth
 staging/src/k8s.io/client-go/discovery
+staging/src/k8s.io/client-go/examples/create-update-delete-deployment
 staging/src/k8s.io/client-go/examples/in-cluster
 staging/src/k8s.io/client-go/examples/out-of-cluster
 staging/src/k8s.io/client-go/examples/third-party-resources

staging/src/k8s.io/client-go/examples/create-update-delete-deployment/BUILD

@@ -0,0 +1,29 @@
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_binary",
+    "go_library",
+)
+
+go_binary(
+    name = "create-update-delete-deployment",
+    library = ":go_default_library",
+    tags = ["automanaged"],
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["main.go"],
+    tags = ["automanaged"],
+    deps = [
+        "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//vendor/k8s.io/client-go/kubernetes:go_default_library",
+        "//vendor/k8s.io/client-go/pkg/api/v1:go_default_library",
+        "//vendor/k8s.io/client-go/pkg/apis/apps/v1beta1:go_default_library",
+        "//vendor/k8s.io/client-go/tools/clientcmd:go_default_library",
+    ],
+)

staging/src/k8s.io/client-go/examples/create-update-delete-deployment/README.md

@@ -0,0 +1,81 @@
+# Create, Update & Delete Deployment
+
+This example program demonstrates the fundamental operations for managing on
+[Deployment][1] resources, such as `Create`, `List`, `Update` and `Delete`.
+
+You can adopt the source code from this example to write programs that manage
+other types of resources through the Kubernetes API.
+
+## Running this example
+
+Make sure you have a Kubernetes cluster and `kubectl` is configured:
+
+    kubectl get nodes
+
+Compile this example on your workstation:
+
+```
+cd create-update-delete-deployment
+go build -o ./app
+```
+
+Now, run this application on your workstation with your local kubeconfig file:
+
+```
+./app -kubeconfig=$HOME/.kube/config
+```
+
+Running this command will execute the following operations on your cluster:
+
+1. **Create Deployment:** This will create a 2 replica Deployment. Verify with
+   `kubectl get pods`.
+2. **Update Deployment:** This will update the Deployment resource created in
+   previous step to set the replica count to 1 and add annotations. You are
+   encouraged to inspect the retry loop that handles conflicts. Verify the new
+   replica count and `foo=bar` annotation with `kubectl describe deployment
+   demo`.
+3. **List Deployments:** This will retrieve Deployments in the `default`
+   namespace and print their names and replica counts.
+4. **Delete Deployment:** This will delete the Deployment object and its
+   dependent ReplicaSet resource. Verify with `kubectl get deployments`.
+
+Each step is separated by an interactive prompt. You must hit the
+<kbd>Return</kbd> key to proceeed to the next step. You can use these prompts as
+a break to take time to  run `kubectl` and inspect the result of the operations
+executed.
+
+You should see an output like the following:
+
+```
+Creating deployment...
+Created deployment "demo-deployment".
+-> Press Return key to continue.
+
+Updating deployment...
+Updated deployment...
+-> Press Return key to continue.
+
+Listing deployments in namespace "default":
+ * demo-deployment (1 replicas)
+-> Press Return key to continue.
+
+Deleting deployment...
+Deleted deployment.
+```
+
+## Cleanup
+
+Successfully running this program will clean the created artifacts. If you
+terminate the program without completing, you can clean up the created
+deployment with:
+
+    kubectl delete deploy demo-deployment
+
+## Troubleshooting
+
+If you are getting the following error, make sure Kubernetes version of your
+cluster is v1.6 or above in `kubectl version`:
+
+    panic: the server could not find the requested resource
+
+[1]: https://kubernetes.io/docs/user-guide/deployments/

staging/src/k8s.io/client-go/examples/create-update-delete-deployment/main.go

@@ -0,0 +1,165 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Note: the example only works with the code within the same release/branch.
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"os"
+
+	"k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	apiv1 "k8s.io/client-go/pkg/api/v1"
+	appsv1beta1 "k8s.io/client-go/pkg/apis/apps/v1beta1"
+	"k8s.io/client-go/tools/clientcmd"
+	// Uncomment the following line to load the gcp plugin (only required to authenticate against GKE clusters).
+	// _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
+)
+
+func main() {
+	kubeconfig := flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
+	flag.Parse()
+	if *kubeconfig == "" {
+		panic("-kubeconfig not specified")
+	}
+	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
+	if err != nil {
+		panic(err)
+	}
+	clientset, err := kubernetes.NewForConfig(config)
+	if err != nil {
+		panic(err)
+	}
+
+	deploymentsClient := clientset.AppsV1beta1().Deployments(apiv1.NamespaceDefault)
+
+	deployment := &appsv1beta1.Deployment{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "demo-deployment",
+		},
+		Spec: appsv1beta1.DeploymentSpec{
+			Replicas: int32Ptr(2),
+			Template: apiv1.PodTemplateSpec{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						"app": "demo",
+					},
+				},
+				Spec: apiv1.PodSpec{
+					Containers: []apiv1.Container{
+						{
+							Name:  "web",
+							Image: "nginx:1.13",
+							Ports: []apiv1.ContainerPort{
+								{
+									Name:          "http",
+									Protocol:      apiv1.ProtocolTCP,
+									ContainerPort: 80,
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	// Create Deployment
+	fmt.Println("Creating deployment...")
+	result, err := deploymentsClient.Create(deployment)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("Created deployment %q.\n", result.GetObjectMeta().GetName())
+
+	// Update Deployment
+	prompt()
+	fmt.Println("Updating deployment...")
+	//    You have two options to Update() this Deployment:
+	//
+	//    1. Modify the "deployment" variable and call: Update(deployment).
+	//       This works like the "kubectl replace" command and it overwrites/loses changes
+	//       made by other clients between you Create() and Update() the object.
+	//    2. Modify the "result" returned by Create()/Get() and retry Update(result) until
+	//       you no longer get a conflict error. This way, you can preserve changes made
+	//       by other clients between Create() and Update(). This is implemented below:
+
+	for {
+		result.Spec.Replicas = int32Ptr(1)                    // reduce replica count
+		result.Spec.Template.Annotations = map[string]string{ // add annotations
+			"foo": "bar",
+		}
+
+		if _, err := deploymentsClient.Update(result); errors.IsConflict(err) {
+			// Deployment is modified in the meanwhile, query the latest version
+			// and modify the retrieved object.
+			fmt.Println("encountered conflict, retrying")
+			result, err = deploymentsClient.Get("demo-deployment", metav1.GetOptions{})
+			if err != nil {
+				panic(fmt.Errorf("Get failed: %+v", err))
+			}
+		} else if err != nil {
+			panic(err)
+		} else {
+			break
+		}
+
+		// TODO: You should sleep here with an exponential backoff to avoid
+		// exhausting the apiserver, and add a limit/timeout on the retries to
+		// avoid getting stuck in this loop indefintiely.
+	}
+	fmt.Println("Updated deployment...")
+
+	// List Deployments
+	prompt()
+	fmt.Printf("Listing deployments in namespace %q:\n", apiv1.NamespaceDefault)
+	list, err := deploymentsClient.List(metav1.ListOptions{})
+	if err != nil {
+		panic(err)
+	}
+	for _, d := range list.Items {
+		fmt.Printf(" * %s (%d replicas)\n", d.Name, *d.Spec.Replicas)
+	}
+
+	// Delete Deployment
+	prompt()
+	fmt.Println("Deleting deployment...")
+	deletePolicy := metav1.DeletePropagationForeground
+	if err := deploymentsClient.Delete("demo-deployment", &metav1.DeleteOptions{
+		PropagationPolicy: &deletePolicy,
+	}); err != nil {
+		panic(err)
+	}
+	fmt.Println("Deleted deployment.")
+}
+
+func prompt() {
+	fmt.Printf("-> Press Return key to continue.")
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		break
+	}
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+	fmt.Println()
+}
+
+func int32Ptr(i int32) *int32 { return &i }