netdata/netdata

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

package k8sclient

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

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

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

const (
    EnvFakeClient    = "KUBERNETES_FAKE_CLIENTSET"
    defaultUserAgent = "Netdata/k8s-client"
)

func New(userAgent string) (kubernetes.Interface, error) {
    if userAgent == "" {
        userAgent = defaultUserAgent
    }

    switch {
    case os.Getenv(EnvFakeClient) != "":
        return fake.NewSimpleClientset(), nil
    case os.Getenv("KUBERNETES_SERVICE_HOST") != "" && os.Getenv("KUBERNETES_SERVICE_PORT") != "":
        return newInCluster(userAgent)
    default:
        return newOutOfCluster(userAgent)
    }
}

func newInCluster(userAgent string) (*kubernetes.Clientset, error) {
    config, err := rest.InClusterConfig()
    if err != nil {
        return nil, err
    }

    config.UserAgent = userAgent

    return kubernetes.NewForConfig(config)
}

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

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

    config.UserAgent = userAgent

    return kubernetes.NewForConfig(config)
}

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