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clientgo/examples/out-of-cluster: add instructions

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Adding instructions for out-of-cluster example and making it work without
specifying the -kubeconfig argument if the home directory can be inferred.

This is part of the body of work improving the client library samples.

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>
This commit is contained in:
Ahmet Alp Balkan 2017-05-19 13:40:18 -07:00
parent 8594af7676
commit e59f05fe0e
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GPG Key ID: 3300B90BF29C804E
2 changed files with 53 additions and 3 deletions
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34
staging/src/k8s.io/client-go/examples/out-of-cluster/README.md Normal file
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@ -0,0 +1,34 @@
# Authenticating outside the cluster
This example shows you how to authenticate to the Kubernetes API from an
application running outside the Kubernetes cluster with client-go.
You can use your kubeconfig file that contains the context information
of your cluster to initialize a client. The kubeconfig file is also used
by the `kubectl` command to authenticate to the clusters.
## Running this example
Make sure your `kubectl` is configured and pointed to a cluster. Run
`kubectl get nodes` to confirm.
Run this application with:
cd out-of-cluster
go build -o app .
./app
Running this application will use the kubeconfig file and then authenticate to the
cluster, and print the number of nodes in the cluster every 10 seconds:
$ ./app
There are 3 pods in the cluster
There are 3 pods in the cluster
There are 3 pods in the cluster
...
Press <kbd>Ctrl</kbd>+<kbd>C</kbd> to quit this application.
> **Note:** You can use the `-kubeconfig` option to use a different config file. By default
this program picks up the default file used by kubectl (when `KUBECONFIG`
environment variable is not set).

22
staging/src/k8s.io/client-go/examples/out-of-cluster/main.go
View File

@ -20,6 +20,8 @@ package main
import (
"flag"
"fmt"
"os"
"path/filepath"
"time"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@ -30,14 +32,21 @@ import (
)
func main() {
kubeconfig := flag.String("kubeconfig", "./config", "absolute path to the kubeconfig file")
var kubeconfig *string
if home := homeDir(); home != "" {
kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
} else {
kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
}
flag.Parse()
// uses the current context in kubeconfig
// use the current context in kubeconfig
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
if err != nil {
panic(err.Error())
}
// creates the clientset
// create the clientset
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
panic(err.Error())
@ -51,3 +60,10 @@ func main() {
time.Sleep(10 * time.Second)
}
}
func homeDir() string {
if h := os.Getenv("HOME"); h != "" {
return h
}
return os.Getenv("USERPROFILE") // windows
}