mirror of https://github.com/k3s-io/k3s
client-go: initial examples import
Dr. Stefan Schimanski
parent
d6f7ae2ffb
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7aebe7c079
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/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"fmt"
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"time"
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"k8s.io/client-go/kubernetes"
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"k8s.io/client-go/pkg/api/v1"
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"k8s.io/client-go/rest"
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)
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func main() {
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// creates the in-cluster config
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config, err := rest.InClusterConfig()
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if err != nil {
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panic(err.Error())
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}
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// creates the clientset
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clientset, err := kubernetes.NewForConfig(config)
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if err != nil {
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panic(err.Error())
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}
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for {
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pods, err := clientset.Core().Pods("").List(v1.ListOptions{})
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if err != nil {
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panic(err.Error())
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}
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fmt.Printf("There are %d pods in the cluster\n", len(pods.Items))
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time.Sleep(10 * time.Second)
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}
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}
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/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"flag"
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"fmt"
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"time"
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"k8s.io/client-go/kubernetes"
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"k8s.io/client-go/pkg/api/v1"
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"k8s.io/client-go/tools/clientcmd"
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)
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var (
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kubeconfig = flag.String("kubeconfig", "./config", "absolute path to the kubeconfig file")
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)
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func main() {
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flag.Parse()
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// uses the current context in kubeconfig
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config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
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if err != nil {
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panic(err.Error())
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}
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// creates the clientset
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clientset, err := kubernetes.NewForConfig(config)
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if err != nil {
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panic(err.Error())
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}
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for {
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pods, err := clientset.Core().Pods("").List(v1.ListOptions{})
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if err != nil {
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panic(err.Error())
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}
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fmt.Printf("There are %d pods in the cluster\n", len(pods.Items))
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time.Sleep(10 * time.Second)
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}
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}
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# Third Party Resources Example
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This particular example demonstrates how to perform basic operations such as:
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* How to register a new ThirdPartyResource (custom Resource type)
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* How to create/get/list instances of your new Resource type (update/delete/etc work as well but are not demonstrated)
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## Running
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```
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# assumes you have a working kubeconfig, not required if operating in-cluster
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go run *.go -kubeconfig=$HOME/.kube/config
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```
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## Use Cases
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ThirdPartyResources can be used to implement custom Resource types for your Kubernetes cluster.
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These act like most other Resources in Kubernetes, and may be `kubectl apply`'d, etc.
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Some example use cases:
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* Provisioning/Management of external datastores/databases (eg. CloudSQL/RDS instances)
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* Higher level abstractions around Kubernetes primitives (eg. a single Resource to define an etcd cluster, backed by a Service and a ReplicationController)
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## Defining types
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Each instance of your ThirdPartyResource has an attached Spec, which should be defined via a `struct{}` to provide data format validation.
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In practice, this Spec is arbitrary key-value data that specifies the configuration/behavior of your Resource.
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For example, if you were implementing a ThirdPartyResource for a Database, you might provide a DatabaseSpec like the following:
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``` go
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type DatabaseSpec struct {
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Databases []string `json:"databases"`
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Users []User `json:"users"`
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Version string `json:"version"`
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}
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type User struct {
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Name string `json:"name"`
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Password string `json:"password"`
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}
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```
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package main
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import (
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"flag"
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"fmt"
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"k8s.io/client-go/kubernetes"
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"k8s.io/client-go/pkg/api"
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"k8s.io/client-go/pkg/api/errors"
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"k8s.io/client-go/pkg/api/v1"
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"k8s.io/client-go/pkg/apis/extensions/v1beta1"
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metav1 "k8s.io/client-go/pkg/apis/meta/v1"
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"k8s.io/client-go/pkg/runtime"
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"k8s.io/client-go/pkg/runtime/schema"
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"k8s.io/client-go/pkg/runtime/serializer"
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"k8s.io/client-go/rest"
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"k8s.io/client-go/tools/clientcmd"
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// Only required to authenticate against GKE clusters
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_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
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)
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var (
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config *rest.Config
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)
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func main() {
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kubeconfig := flag.String("kubeconfig", "", "Path to a kube config. Only required if out-of-cluster.")
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flag.Parse()
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// Create the client config. Use kubeconfig if given, otherwise assume in-cluster.
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config, err := buildConfig(*kubeconfig)
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if err != nil {
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panic(err)
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}
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clientset, err := kubernetes.NewForConfig(config)
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if err != nil {
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panic(err)
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}
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// initialize third party resource if it does not exist
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tpr, err := clientset.Extensions().ThirdPartyResources().Get("example.k8s.io", metav1.GetOptions{})
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if err != nil {
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if errors.IsNotFound(err) {
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tpr := &v1beta1.ThirdPartyResource{
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ObjectMeta: v1.ObjectMeta{
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Name: "example.k8s.io",
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},
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Versions: []v1beta1.APIVersion{
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{Name: "v1"},
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},
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Description: "An Example ThirdPartyResource",
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}
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result, err := clientset.Extensions().ThirdPartyResources().Create(tpr)
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if err != nil {
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panic(err)
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}
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fmt.Printf("CREATED: %#v\nFROM: %#v\n", result, tpr)
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} else {
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panic(err)
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}
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} else {
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fmt.Printf("SKIPPING: already exists %#v\n", tpr)
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}
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// make a new config for our extension's API group, using the first config as a baseline
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var tprconfig *rest.Config
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tprconfig = config
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configureClient(tprconfig)
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tprclient, err := rest.RESTClientFor(tprconfig)
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if err != nil {
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panic(err)
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}
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var example Example
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err = tprclient.Get().
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Resource("examples").
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Namespace(api.NamespaceDefault).
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Name("example1").
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Do().Into(&example)
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if err != nil {
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if errors.IsNotFound(err) {
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// Create an instance of our TPR
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example := &Example{
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Metadata: api.ObjectMeta{
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Name: "example1",
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},
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Spec: ExampleSpec{
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Foo: "hello",
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Bar: true,
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},
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}
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var result Example
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err = tprclient.Post().
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Resource("examples").
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Namespace(api.NamespaceDefault).
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Body(example).
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Do().Into(&result)
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if err != nil {
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panic(err)
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}
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fmt.Printf("CREATED: %#v\n", result)
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} else {
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panic(err)
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}
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} else {
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fmt.Printf("GET: %#v\n", example)
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}
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// Fetch a list of our TPRs
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exampleList := ExampleList{}
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err = tprclient.Get().Resource("examples").Do().Into(&exampleList)
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if err != nil {
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panic(err)
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}
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fmt.Printf("LIST: %#v\n", exampleList)
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}
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func buildConfig(kubeconfig string) (*rest.Config, error) {
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if kubeconfig != "" {
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return clientcmd.BuildConfigFromFlags("", kubeconfig)
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}
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return rest.InClusterConfig()
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}
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func configureClient(config *rest.Config) {
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groupversion := schema.GroupVersion{
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Group: "k8s.io",
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Version: "v1",
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}
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config.GroupVersion = &groupversion
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config.APIPath = "/apis"
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config.ContentType = runtime.ContentTypeJSON
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config.NegotiatedSerializer = serializer.DirectCodecFactory{CodecFactory: api.Codecs}
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schemeBuilder := runtime.NewSchemeBuilder(
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func(scheme *runtime.Scheme) error {
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scheme.AddKnownTypes(
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groupversion,
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&Example{},
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&ExampleList{},
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&api.ListOptions{},
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&api.DeleteOptions{},
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)
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return nil
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})
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schemeBuilder.AddToScheme(api.Scheme)
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}
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@ -0,0 +1,78 @@
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package main
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import (
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"encoding/json"
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"k8s.io/client-go/pkg/api"
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"k8s.io/client-go/pkg/api/meta"
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metav1 "k8s.io/client-go/pkg/apis/meta/v1"
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"k8s.io/client-go/pkg/runtime/schema"
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)
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type ExampleSpec struct {
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Foo string `json:"foo"`
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Bar bool `json:"bar"`
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}
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type Example struct {
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metav1.TypeMeta `json:",inline"`
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Metadata api.ObjectMeta `json:"metadata"`
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Spec ExampleSpec `json:"spec"`
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}
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type ExampleList struct {
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metav1.TypeMeta `json:",inline"`
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Metadata metav1.ListMeta `json:"metadata"`
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Items []Example `json:"items"`
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}
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// Required to satisfy Object interface
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func (e *Example) GetObjectKind() schema.ObjectKind {
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return &e.TypeMeta
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}
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// Required to satisfy ObjectMetaAccessor interface
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func (e *Example) GetObjectMeta() meta.Object {
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return &e.Metadata
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}
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// Required to satisfy Object interface
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func (el *ExampleList) GetObjectKind() schema.ObjectKind {
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return &el.TypeMeta
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}
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// Required to satisfy ListMetaAccessor interface
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func (el *ExampleList) GetListMeta() metav1.List {
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return &el.Metadata
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}
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// The code below is used only to work around a known problem with third-party
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// resources and ugorji. If/when these issues are resolved, the code below
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// should no longer be required.
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type ExampleListCopy ExampleList
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type ExampleCopy Example
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func (e *Example) UnmarshalJSON(data []byte) error {
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tmp := ExampleCopy{}
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err := json.Unmarshal(data, &tmp)
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if err != nil {
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return err
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}
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tmp2 := Example(tmp)
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*e = tmp2
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return nil
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}
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func (el *ExampleList) UnmarshalJSON(data []byte) error {
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tmp := ExampleListCopy{}
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err := json.Unmarshal(data, &tmp)
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if err != nil {
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return err
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}
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tmp2 := ExampleList(tmp)
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*el = tmp2
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return nil
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}
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