firehol/netdata

// SPDX-License-Identifier: GPL-3.0-or-later

package k8s_state

import (
    "errors"
    "os"
    "path/filepath"

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

    _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"

    "github.com/mattn/go-isatty"
)

const (
    envKubeServiceHost = "KUBERNETES_SERVICE_HOST"
    envKubeServicePort = "KUBERNETES_SERVICE_PORT"
)

func newKubeClient() (kubernetes.Interface, error) {
    if os.Getenv(envKubeServiceHost) != "" && os.Getenv(envKubeServicePort) != "" {
        return newKubeClientInCluster()
    }
    if isatty.IsTerminal(os.Stdout.Fd()) {
        return newKubeClientOutOfCluster()
    }
    return nil, errors.New("can not create Kubernetes client: not inside a cluster")
}

func newKubeClientInCluster() (*kubernetes.Clientset, error) {
    config, err := rest.InClusterConfig()
    if err != nil {
        return nil, err
    }
    config.UserAgent = "Netdata/kube-state"
    return kubernetes.NewForConfig(config)
}

func newKubeClientOutOfCluster() (*kubernetes.Clientset, error) {
    home := homeDir()
    if home == "" {
        return nil, errors.New("couldn't find home directory")
    }

    configPath := filepath.Join(home, ".kube", "config")
    config, err := clientcmd.BuildConfigFromFlags("", configPath)
    if err != nil {
        return nil, err
    }

    config.UserAgent = "Netdata/kube-state"
    return kubernetes.NewForConfig(config)
}

func homeDir() string {
    if h := os.Getenv("HOME"); h != "" {
        return h
    }
    return os.Getenv("USERPROFILE") // windows
}