Question 103384 in Azure Question posted in
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Azure – K8S Provide kubeconfig as bytearray genericclioptions

Is there any way to pass to &genericclioptions of k8s client a bytearray of the kubeconfig?

https://pkg.go.dev/k8s.io/cli-runtime/pkg/genericclioptions

Currently, the genericclioptionsits is taking it by default from the env/path to the file, but I need to pass it explicitly as bytearray as a parameter and not a ref to a file or from the env, is there a way to do it?

I tried the following but it doesn’t work:

package main

import (
    "bytes"
    "github.com/spf13/pflag"
    "k8s.io/cli-runtime/pkg/genericclioptions"
)

func main() {
    kubeconfigData := []byte("my_kubeconfig")

    // create a new flag set and bind the kubeconfig flag
    flags := pflag.NewFlagSet("default", pflag.ExitOnError)
    kubeconfigFlag := flags.String("kubeconfig", "", "absolute path to the kubeconfig file")
    flags.Parse([]string{})

    // set the kubeconfig flag to the data in the byte array
    *kubeconfigFlag = "-"
    configOverrides := &genericclioptions.ConfigOverrides{ClusterDefaults: genericclioptions.NewClusterDefaults()}
    configLoader := genericclioptions.NewConfigFlags(false).WithOverrideFlags(configOverrides)
    configLoader.KubeConfig = bytes.NewBuffer(kubeconfigData)

    // ...
}

Any idea?

SECOND TRY
I tried also the following version and I got error: error loading config file , any idea?

func main() {
    // read the kubeconfig file into a byte array
    kubeconfig, err := ioutil.ReadFile("./kubeconfig--pln.yaml")
    if err != nil {
        panic(err)
    }

    // create a ConfigFlags object with the kubeconfig byte array
    flags := genericclioptions.NewConfigFlags(false)
    *flags.KubeConfig = string(kubeconfig)
    dc, err := flags.ToDiscoveryClient()
    if err != nil {
        fmt.Println(err)
    }
    fmt.Println(dc)

    res, err := dc.ServerPreferredNamespacedResources()
    if err != nil {
        fmt.Println(res)
    }

    // use the flags object to create a clientset or other Kubernetes API object
    // ...
}
Tags:

2

Answers


  1. 0

    The code you posted is trying to set the kubeconfig flag to a string value of "-" instead of the byte array. To pass the kubeconfig as a byte array, you need to set the KubeConfig field of the ConfigLoader to a bytes.Buffer created from the byte array.

    Here’s an updated version of the code:

    package main

import (
    "bytes"
    "github.com/spf13/pflag"
    "k8s.io/cli-runtime/pkg/genericclioptions"
)

func main() {
    kubeconfigData := []byte("my_kubeconfig")

    configOverrides := &genericclioptions.ConfigOverrides{ClusterDefaults: genericclioptions.NewClusterDefaults()}
    configLoader := genericclioptions.NewConfigFlags(false).WithOverrideFlags(configOverrides)
    configLoader.KubeConfig = bytes.NewBuffer(kubeconfigData)

    // ...
}

    Try the above code once, also u can follow these link1 Link2 Link3 Link4

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  2. 0

    Depending on how the config is used, one option might be to bypass the config loader step entirely.

    For example:

    func getClientCmdConfig() (*clientcmdapi.Config, error) {
   kubeconfigData := []byte("my_kubeconfig")
   var cfg clientcmdapi.Config
   if err := json.Unmarshal(kubeconfigData, &cfg); err != nil {
      return nil, err
   }
   return &cfg, nil
}

func useClientCmdConfig() (..., error) {
   cfg, err := getClientCmdConfig()
   if err != nil {
      return ..., err
   }
   
   clientCfg, err := genericclioptions.NewDefaultClientConfig
   if err != nil {
      return ..., err
   }

   // ... do something with clientCfg
}
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