Backup Kube Config to Helm Config Directory

Backup kubeconfig to <helm-config-path>/kubeconfig
during initialization of subcommands (env, install, etc.)
The backup file will have rw permissions for user.
All subcommands will then use backup kubeconfig file.

Signed-off-by: Bhargav Ravuri <bhargav.ravuri@infracloud.io>

cmd/helm/helm.go

@@ -72,6 +72,18 @@ func main() {
 	// run when each command's execute method is called
 	cobra.OnInitialize(func() {
 		helmDriver := os.Getenv("HELM_DRIVER")
+
+		if settings.KubeConfig != "" {
+			// If KubeConfig path is not empty, backup kube config to: <helm-config-path>/kubeconfig
+			// When the backup is successful, the settings.KubeConfig path is updated to backup file's path.
+			err = settings.BackupKubeConfig()
+			if err != nil {
+				log.Fatal(err)
+			}
+		} else {
+			debug("kube config backup aborted due to empty KubeConfig path in settings")
+		}
+
 		if err := actionConfig.Init(settings.RESTClientGetter(), settings.Namespace(), helmDriver, debug); err != nil {
 			log.Fatal(err)
 		}

pkg/cli/environment.go

@@ -27,6 +27,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 
@@ -34,6 +35,7 @@ import (
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/client-go/rest"
 
+	"helm.sh/helm/v3/internal/fileutil"
 	"helm.sh/helm/v3/internal/version"
 	"helm.sh/helm/v3/pkg/helmpath"
 )
@@ -235,3 +237,41 @@ func (s *EnvSettings) SetNamespace(namespace string) {
 func (s *EnvSettings) RESTClientGetter() genericclioptions.RESTClientGetter {
 	return s.config
 }
+
+// BackupKubeConfig copies kube config file to <helm-config-path>/kubeconfig
+// as backup. The backup file will have rw permissions for user.
+// The backup file's path is updated in EnvSettings.KubeConfig.
+//
+// There is no safety check on EnvSettings.KubeConfig, i.e., the caller
+// should call this method only when there is kube config path specified.
+// Else, the actual kubeconfig file read fails.
+func (s *EnvSettings) BackupKubeConfig() error {
+	// Form the backup file path as: <helm-config-path>/kubeconfig
+	// The helm-config-path is derived from envs HELM_CONFIG_HOME,
+	// XDG_CONFIG_HOME and default path. Defaults paths:
+	// 	- Linux	 : $HOME/.config/helm
+	// 	- Mac	 : $HOME/Library/Preferences/helm
+	// 	- Windows : %APPDATA%\helm
+	helmConfigPath := helmpath.ConfigPath("")
+	kubeConfigBackupFilename := filepath.Join(helmConfigPath, "kubeconfig")
+
+	// Create reader from actual kube config file
+	kubeConfigReader, err := os.Open(s.KubeConfig)
+	if err != nil {
+		return fmt.Errorf("failed to read input kubeconfig file %q: %v",
+			s.KubeConfig, err)
+	}
+	defer kubeConfigReader.Close()
+
+	// Copy actual kube config file to backup file
+	err = fileutil.AtomicWriteFile(kubeConfigBackupFilename, kubeConfigReader, 0600)
+	if err != nil {
+		return fmt.Errorf("failed to copy kubeconfig from %q to %q: %v",
+			s.KubeConfig, kubeConfigBackupFilename, err)
+	}
+
+	// Update the kube config in EnvSettings to backup file path
+	s.KubeConfig = kubeConfigBackupFilename
+
+	return nil
+}

pkg/cli/environment_test.go

@@ -263,3 +263,87 @@ func resetEnv() func() {
 		}
 	}
 }
+
+func TestEnvSettings_BackupKubeConfig(t *testing.T) {
+	var (
+		testDataDir        = `testdata/`
+		kubeConfigFilename = testDataDir + "kubeconfig"
+	)
+
+	type fields struct {
+		KubeConfig     string
+		helmConfigHome string
+	}
+
+	type toggles struct {
+		wantErr               bool
+		cleanUpTestKubeConfig bool
+	}
+
+	type testCase struct {
+		name    string
+		fields  fields
+		toggles toggles
+	}
+
+	tests := []testCase{
+		{
+			name: "Backup kube config",
+			fields: fields{
+				KubeConfig:     testDataDir + `valid-kubeconfig-no-contexts`,
+				helmConfigHome: testDataDir,
+			},
+			toggles: toggles{
+				cleanUpTestKubeConfig: true,
+			},
+		},
+		{
+			name: "Failure missing input kube config file",
+			fields: fields{
+				KubeConfig:     testDataDir + `missing-kubeconfig`,
+				helmConfigHome: testDataDir,
+			},
+			toggles: toggles{
+				wantErr: true,
+			},
+		},
+		{
+			name: "Failure invalid destination path",
+			fields: fields{
+				KubeConfig:     testDataDir + `valid-kubeconfig-no-contexts`,
+				helmConfigHome: testDataDir + `non-existing-dir/`,
+			},
+			toggles: toggles{
+				wantErr: true,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := &EnvSettings{
+				KubeConfig: tt.fields.KubeConfig,
+			}
+
+			t.Setenv(`HELM_CONFIG_HOME`, tt.fields.helmConfigHome)
+
+			err := s.BackupKubeConfig()
+			if (err != nil) != tt.toggles.wantErr {
+				t.Errorf("EnvSettings.BackupKubeConfig() error = %v, wantErr %v",
+					err, tt.toggles.wantErr)
+			}
+
+			if !tt.toggles.wantErr && s.KubeConfig != kubeConfigFilename {
+				t.Errorf("kube config path not updated after backup, want = %s, got = %s",
+					kubeConfigFilename, s.KubeConfig)
+			}
+
+			if tt.toggles.cleanUpTestKubeConfig {
+				err = os.Remove(kubeConfigFilename)
+				if err != nil {
+					t.Errorf("failed to delete %q: %v", kubeConfigFilename, err)
+				}
+			}
+		})
+	}
+}

pkg/cli/testdata/valid-kubeconfig-no-contexts

@@ -0,0 +1,11 @@
+apiVersion: v1
+clusters: null
+contexts: null
+current-context: ""
+kind: Config
+preferences: {}
+users:
+- name: kubeuser/
+  user:
+    password: password
+    username: user