如何从.kube / config中设置的当前上下文获取名称空间

Question

I am trying to get programmatically in Go, the namespace of the current-context from ~/.kube/config.

So far what I tried is from these modules:

    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/kubernetes"



kubeconfig := filepath.Join(
     os.Getenv("HOME"), ".kube", "config",
)
config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("Namespace: %s
", config.Namespace())
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
    log.Fatal(err)
}

But still no clue if clientset can give me the namespace I am looking for. From this thread: How to get current namespace of an in-cluster go Kubernetes client

It says something of this to be done: kubeconfig.Namespace()

Answer 1

I found a solution using NewDefaultClientConfigLoadingRules and then loading the rules. This works if your config is loadable with the default client config loading rules.

Example:

package main

import (
        "github.com/davecgh/go-spew/spew"
        "k8s.io/client-go/tools/clientcmd"
)

func main() {
        clientCfg, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
        spew.Dump(clientCfg, err)
}

Gives you a https://godoc.org/k8s.io/client-go/tools/clientcmd/api#Config which contains the current context including its namespace.

Contexts: (map[string]*api.Context) (len=1) {
  (string) (len=17) "xxx.xxxxx.xxx": (*api.Context)(0xc0001b2b40)({
   LocationOfOrigin: (string) (len=30) "/path/to/.kube/config",
   Cluster: (string) (len=17) "xxx.xxxxx.xxx",
   AuthInfo: (string) (len=29) "[e-mail]",
   Namespace: (string) (len=7) "default",
   Extensions: (map[string]runtime.Object) {
   }
  })
 },
 CurrentContext: (string) (len=17) "xxx.xxxxx.xxx",

For your information, ClientConfigLoadingRules is a structure with different properties to tell the cliclient where to load the config from. The default one will use the path in your KUBECONFIG environment variable in the Precedence field.

(*clientcmd.ClientConfigLoadingRules)(0xc0000a31d0)({
 ExplicitPath: (string) "",
 Precedence: ([]string) (len=1 cap=1) {
  (string) (len=30) "/path/to/.kube/config"
 },
 MigrationRules: (map[string]string) (len=1) {
  (string) (len=30) "/path/to/.kube/config": (string) (len=35) "/path/to/.kube/.kubeconfig"
 },
 DoNotResolvePaths: (bool) false,
 DefaultClientConfig: (clientcmd.ClientConfig) <nil>
})